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Journal articles on the topic 'Cosmic infall'
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Jiang, I. G., and J. Binney. "Warps and cosmic infall." Monthly Notices of the Royal Astronomical Society 303, no. 1 (February 11, 1999): L7—L10. http://dx.doi.org/10.1046/j.1365-8711.1999.02333.x.
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Shen, J., and J. A. Sellwood. "Galactic warps induced by cosmic infall." Monthly Notices of the Royal Astronomical Society 370, no. 1 (July 21, 2006): 2–14. http://dx.doi.org/10.1111/j.1365-2966.2006.10477.x.
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Kraljic, Katarina, Christophe Pichon, Sandrine Codis, Clotilde Laigle, Romeel Davé, Yohan Dubois, Ho Seong Hwang, et al. "The impact of the connectivity of the cosmic web on the physical properties of galaxies at its nodes." Monthly Notices of the Royal Astronomical Society 491, no. 3 (November 27, 2019): 4294–309. http://dx.doi.org/10.1093/mnras/stz3319.
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ABSTRACT We investigate the impact of the number of filaments connected to the nodes of the cosmic web on the physical properties of their galaxies using the Sloan Digital Sky Survey. We compare these measurements to the cosmological hydrodynamical simulations H orizon-(no)AGN and Simba. We find that more massive galaxies are more connected, in qualitative agreement with theoretical predictions and measurements in dark-matter-only simulations. The star formation activity and morphology of observed galaxies both display some dependence on the connectivity of the cosmic web at a fixed stellar mass: Less star forming and less rotation supported galaxies also tend to have higher connectivity. These results qualitatively hold both for observed and for virtual galaxies, and can be understood given that the cosmic web is the main source of fuel for galaxy growth. The simulations show the same trends at a fixed halo mass, suggesting that the geometry of filamentary infall impacts galaxy properties beyond the depth of the local potential well. Based on simulations, it is also found that active galactic nucleus feedback is key to reversing the relationship between stellar mass and connectivity at a fixed halo mass. Technically, connectivity is a practical observational proxy for past and present accretion (minor mergers or diffuse infall).
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Libeskind, Noam I. "The beaming of subhalo accretion." Proceedings of the International Astronomical Union 11, S308 (June 2014): 456–61. http://dx.doi.org/10.1017/s174392131601036x.
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AbstractWe examine the infall pattern of subhaloes onto hosts in the context of the large-scale structure. We find that the infall pattern is essentially driven by the shear tensor of the ambient velocity field. Dark matter subhaloes are preferentially accreted along the principal axis of the shear tensor which corresponds to the direction of weakest collapse. We examine the dependence of this preferential infall on subhalo mass, host halo mass and redshift. Although strongest for the most massive hosts and the most massive subhaloes at high redshift, the preferential infall of subhaloes is effectively universal in the sense that its always aligned with the axis of weakest collapse of the velocity shear tensor. It is the same shear tensor that dictates the structure of the cosmic web and hence the shear field emerges as the key factor that governs the local anisotropic pattern of structure formation. Since the small (sub-Mpc) scale is strongly correlated with the mid-range (∼ 10 Mpc) scale - a scale accessible by current surveys of peculiar velocities - it follows that findings presented here open a new window into the relation between the observed large scale structure unveiled by current surveys of peculiar velocities and the preferential infall direction of the Local Group. This may shed light on the unexpected alignments of dwarf galaxies seen in the Local Group.
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Fattahi, Azadeh, Alis J. Deason, Carlos S. Frenk, Christine M. Simpson, Facundo A. Gómez, Robert J. J. Grand, Antonela Monachesi, Federico Marinacci, and Rüdiger Pakmor. "A tale of two populations: surviving and destroyed dwarf galaxies and the build-up of the Milky Way’s stellar halo." Monthly Notices of the Royal Astronomical Society 497, no. 4 (August 6, 2020): 4459–71. http://dx.doi.org/10.1093/mnras/staa2221.
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ABSTRACT We use magnetohydrodynamical simulations of Milky Way-mass haloes from the Auriga project to investigate the properties of surviving and destroyed dwarf galaxies that are accreted by these haloes over cosmic time. We show that the combined luminosity function of surviving and destroyed dwarfs at infall is similar in the various Auriga haloes, and is dominated by the destroyed dwarfs. There is, however, a strong dependence on infall time: destroyed dwarfs typically have early infall times of less than 6 Gyr (since the big bang), whereas the majority of dwarfs accreted after 10 Gyr have survived to the present day. Because of their late infall, the surviving satellites have higher metallicities at infall than their destroyed counterparts of similar mass at infall; the difference is even more pronounced for the present-day metallicities of satellites, many of which continue to form stars after infall, in particular for $M_{\rm star}\gt 10^7 \, {\rm M}_\odot$. In agreement with previous work, we find that a small number of relatively massive destroyed dwarf galaxies dominate the mass of stellar haloes. However, there is a significant radial dependence: while 90 per cent of the mass in the inner regions (${\lt}20\,$ kpc) is contributed, on average, by only three massive progenitors, the outer regions (${\gt}100\,$ kpc) typically have ∼8 main progenitors of relatively lower mass. Finally, we show that a few massive progenitors dominate the metallicity distribution of accreted stars, even at the metal-poor end. Contrary to common assumptions in the literature, stars from dwarf galaxies of mass $M_{\rm star}\lt 10^7 \, {\rm M}_\odot$ make up less than 10 per cent of the accreted, metal poor stars ([Fe/H] ${\lt}-3$) in the inner $50\,$ kpc.
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Impey, Chris D. "Dim Baryons in the Cosmic Web." Proceedings of the International Astronomical Union 3, S244 (June 2007): 157–66. http://dx.doi.org/10.1017/s1743921307013956.
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AbstractThe distribution of baryons beyond galaxies is descibed. The majority of the baryons, which represent 4% of the cosmic mass and energy budget, lie far from individual galaxies in the diffuse intergalactic medium (IGM). Many of these baryons are in a warm phase that can be probed by quasar absorption in the Lyman-α line of hydrogen. The mature field of quasar spectroscopy can diagnose the location, physical state, metallicity, and general geometry of this gas, which is called the “cosmic web.” The remainder of the gas is kept very hot by infall and shocks and is mostly in higher density regions such as filaments, groups and clusters. The hot gas is only detectable via X-rays and the absorption of highly ionized species of heavy elements. The baryons in low density regions of space are excellent tracers of underlying dark matter. The evolution of the cosmic web indicates where to look for the baryons in collapsed objects but the overall inefficiency of galaxy formation has conspired to keep most baryons dark.
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Peper, Marius, and Boudewijn F. Roukema. "The role of the elaphrocentre in void galaxy formation." Monthly Notices of the Royal Astronomical Society 505, no. 1 (May 12, 2021): 1223–38. http://dx.doi.org/10.1093/mnras/stab1342.
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ABSTRACT Voids may affect galaxy formation via weakening mass infall or increasing disk sizes, which could potentially play a role in the formation of giant low surface brightness galaxies (LSBGs). If a dark matter halo forms at the potential hill corresponding to a void of the cosmic web, which we denote the ‘elaphrocentre’ in contrast to a barycentre, then the elaphrocentre should weaken the infall rate to the halo when compared to infall rates towards barycentres. We investigate this hypothesis numerically. We present a complete software pipeline to simulate galaxy formation, starting from a power spectrum of initial perturbations and an N-body simulation through to merger-history-tree based mass infall histories. The pipeline is built from well-established, free-licensed cosmological software packages, and aims at highly portable long-term reproducibility. We find that the elaphrocentric accelerations tending to oppose mass infall are modest. We do not find evidence of location in a void or elaphrocentric position weakening mass infall towards a galaxy. However, we find indirect evidence of voids influencing galaxy formation: while void galaxies are of lower mass compared to galaxies in high-density environments, their spin parameters are typically higher. For a fixed mass, the implied disc scale length would be greater. Tangential accelerations in voids are found to be high and might significantly contribute to the higher spin parameters. We find significantly later formation epochs for void galaxies; this should give lower matter densities and may imply lower surface densities of disc galaxies. Thus, void galaxies have higher spin parameters and later formation epochs; both are factors that may increase the probability of forming LSBGs in voids.
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Kashibadze, Olga G., and Igor D. Karachentsev. "Cosmic flow around local massive galaxies." Astronomy & Astrophysics 609 (December 22, 2017): A11. http://dx.doi.org/10.1051/0004-6361/201731645.
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Aims. We use accurate data on distances and radial velocities of galaxies around the Local Group, as well as around 14 other massive nearby groups, to estimate their radius of the zero-velocity surface, R0, which separates any group against the global cosmic expansion. Methods. Our R0 estimate was based on fitting the data to the velocity field expected from the spherical infall model, including effects of the cosmological constant. The reported uncertainties were derived by a Monte Carlo simulation. Results. Testing various assumptions about a location of the group barycentre, we found the optimal estimates of the radius to be 0.91 ± 0.05 Mpc for the Local Group, and 0.93 ± 0.02 Mpc for a synthetic group stacked from 14 other groups in the Local Volume. Under the standard Planck model parameters, these quantities correspond to the total mass of the group ~ (1.6 ± 0.2) × 1012M⊙. Thus, we are faced with the paradoxical result that the total mass estimate on the scale of R0 ≈ (3−4)Rvir is only 60% of the virial mass estimate. Anyway, we conclude that wide outskirts of the nearby groups do not contain a large amount of hidden mass outside their virial radius.
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Hellwing, Wojciech A. "Dynamics of pairwise motions in the Cosmic Web." Proceedings of the International Astronomical Union 11, S308 (June 2014): 322–27. http://dx.doi.org/10.1017/s1743921316010085.
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AbstractWe present results of analysis of the dark matter (DM) pairwise velocity statistics in different Cosmic Web environments. We use the DM velocity and density field from the Millennium 2 simulation together with the NEXUS+ algorithm to segment the simulation volume into voxels uniquely identifying one of the four possible environments: nodes, filaments, walls or cosmic voids. We show that the PDFs of the mean infall velocities v12 as well as its spatial dependence together with the perpendicular and parallel velocity dispersions bear a significant signal of the large-scale structure environment in which DM particle pairs are embedded. The pairwise flows are notably colder and have smaller mean magnitude in wall and voids, when compared to much denser environments of filaments and nodes. We discuss on our results, indicating that they are consistent with a simple theoretical predictions for pairwise motions as induced by gravitational instability mechanism. Our results indicate that the Cosmic Web elements are coherent dynamical entities rather than just temporal geometrical associations. In addition it should be possible to observationally test various Cosmic Web finding algorithms by segmenting available peculiar velocity data and studying resulting pairwise velocity statistics.
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Almeida, J. Sánchez, A. Olmo-García, B. G. Elmegreen, C. Muñoz-Tuñón, D. M. Elmegreen, M. E. Filho, E. Pérez-Montero, and R. Amorín. "Gas accretion from the cosmic web feeding disk galaxies." Proceedings of the International Astronomical Union 11, S321 (March 2016): 208–10. http://dx.doi.org/10.1017/s1743921316008863.
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AbstractDisk galaxies in cosmological numerical simulations grow by accreting gas from the cosmic web. This gas reaches the external disk, and then spirals in dragged along by tidal forces and/or disk instabilities. The importance of gas infall is as clear from numerical simulations as it is obscure to observations. Extremely metal poor (XMP) galaxies seem to be the best example we have of the gas accretion process at work. They have large off-center starbursts which show significant metallicity drop compared with the host galaxy. This observation is naturally explained as a gas accretion event caught in the act. We present preliminary results of the kinematical properties of the metal poor starbursts in XMPs, which suggest that the starbursts are kinematically decoupled entities within the host galaxy.
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Kuchner, Ulrike, Alfonso Aragón-Salamanca, Agustín Rost, Frazer R. Pearce, Meghan E. Gray, Weiguang Cui, Alexander Knebe, Elena Rasia, and Gustavo Yepes. "Cosmic filaments in galaxy cluster outskirts: quantifying finding filaments in redshift space." Monthly Notices of the Royal Astronomical Society 503, no. 2 (March 1, 2021): 2065–76. http://dx.doi.org/10.1093/mnras/stab567.
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ABSTRACT Inferring line-of-sight distances from redshifts in and around galaxy clusters is complicated by peculiar velocities, a phenomenon known as the ‘Fingers of God’ (FoG). This presents a significant challenge for finding filaments in large observational data sets as these artificial elongations can be wrongly identified as cosmic web filaments by extraction algorithms. Upcoming targeted wide-field spectroscopic surveys of galaxy clusters and their infall regions, such as the WEAVE Wide-Field Cluster Survey, motivate our investigation of the impact of FoG on finding filaments connected to clusters. Using zoom-in resimulations of 324 massive galaxy clusters and their outskirts from the three hundred project, we test methods typically applied to large-scale spectroscopic data sets. This paper describes our investigation of whether a statistical compression of the FoG of cluster centres and galaxy groups can lead to correct filament extractions in the cluster outskirts. We find that within 5R200 (∼15 h−1 Mpc) statistically correcting for FoG elongations of virialized regions does not achieve reliable filament networks compared to reference filament networks based on true positions. This is due to the complex flowing motions of galaxies towards filaments in addition to the cluster infall, which overwhelm the signal of the filaments relative to the volume that we probe. While information from spectroscopic redshifts is still important to isolate the cluster regions, and thereby reduce background and foreground interlopers, we expect future spectroscopic surveys of galaxy cluster outskirts to rely on 2D positions of galaxies to extract cosmic filaments.
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Mayer, Lucio. "Environmental Mechanisms Shaping the Nature of Dwarf Spheroidal Galaxies: The View of Computer Simulations." Advances in Astronomy 2010 (2010): 1–21. http://dx.doi.org/10.1155/2010/278434.
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We review numerical works carried out over the last decade on the role of environmental mechanisms in shaping nature of the faintest galaxies known, dwarf spheroidals (dSphs). The combination of tidally induced morphological transformation, termed tidal stirring, with mass loss due to tidal and ram-pressure stripping aided by heating due to the cosmic ionizing background can turn late-type dwarfs resembling present-day dIrrs into classic dSphs. The time of infall into the primary halo is shown to be a key parameter. Dwarfs accreting at when the cosmic ultraviolet ionizing flux was much higher than today, and was thus able to keep the gas in the dwarfs warm and diffuse, were rapidly stripped of their baryons via ram pressure and tidal forces, producing very dark-matter-dominated objects with truncated star-formation histories, such as the Draco dSph. The low star-formation efficiency expected in such low-metallicity objects prior to their infall was crucial for keeping their disks gas dominated until stripping took over.Therefore gas stripping along with inefficient star-formation provides a new feedback mechanism, alternative to photoevaporation or supernovae feedback, playing a crucial role in dwarf galaxy formation and evolution. We also discuss how the ultra-faint dSphs belong to a different population of lower-mass dwarf satellites that were mostly shaped by reionization rather than by environmental mechanisms (“reionization fossils”). Finally, we scrutinize the various caveats in the current understanding of environmental effects as well as other recent ideas on the origin of Local Group dSphs.
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Blaña, Matías, Andreas Burkert, Michael Fellhauer, Marc Schartmann, and Christian Alig. "Dwarfs in the Milky Way halo outer rim: first infall or backsplash satellites?" Monthly Notices of the Royal Astronomical Society 497, no. 3 (August 6, 2020): 3601–22. http://dx.doi.org/10.1093/mnras/staa2153.
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ABSTRACT Leo T is a gas-rich dwarf located at $414\, {\rm kpc}$ (1.4Rvir) distance from the Milky Way (MW) and it is currently assumed to be on its first approach. Here, we present an analysis of orbits calculated backwards in time for the dwarf with our new code delorean, exploring a range of systematic uncertainties, e.g. MW virial mass and accretion, M31 potential, and cosmic expansion. We discover that orbits with tangential velocities in the Galactic standard-of-rest frame lower than $| \vec{u}_{\rm t}^{\rm GSR}| \le 63^{+47}_{-39}\, {\rm km}\, {\rm s}^{\rm -1}$ result in backsplash solutions, i.e. orbits that entered and left the MW dark matter halo in the past, and that velocities above $| \vec{u}_{\rm t}^{\rm GSR}| \ge 21^{+33}_{-21}\, {\rm km}\, {\rm s}^{\rm -1}$ result in wide-orbit backsplash solutions with a minimum pericentre range of $D_{\rm min} \ge 38^{+26}_{-16}\, {\rm kpc}$, which would allow this satellite to survive gas stripping and tidal disruption. Moreover, new proper motion estimates overlap with our orbital solution regions. We applied our method to other distant MW satellites, finding a range of gas stripped backsplash solutions for the gasless Cetus and Eridanus II, providing a possible explanation for their lack of cold gas, while only first infall solutions are found for the H i-rich Phoenix I. We also find that the cosmic expansion can delay their first pericentre passage when compared to the non-expanding scenario. This study explores the provenance of these distant dwarfs and provides constraints on the environmental and internal processes that shaped their evolution and current properties.
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Aubert, D., C. Pichon, and S. Colombi. "The origin and implications of dark matter anisotropic cosmic infall on ≈L★haloes." Monthly Notices of the Royal Astronomical Society 352, no. 2 (August 2004): 376–98. http://dx.doi.org/10.1111/j.1365-2966.2004.07883.x.
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Pomarède, Daniel, Hélène Courtois, and R. Brent Tully. "Visualization of structures and cosmic flows in the local Universe." Proceedings of the International Astronomical Union 8, S289 (August 2012): 323–26. http://dx.doi.org/10.1017/s174392131202162x.
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AbstractA visualization of 3D structures and cosmic flows is presented using information from the Extragalactic Distance Database V8k redshift catalog and peculiar velocities from the Cosmicflows-1 survey. Structures within a volume bounded at 8000 km s−1 on the cardinal Supergalactic axes are explored in terms of both displaying the positions of the 30,124 galaxies of the catalog and its reconstructed luminosity density field, corrected to account for growing incompleteness with increasing distance. Cosmography of the local Universe is discussed with the intent to identify the most prominent structures, including voids, galaxy clusters, filaments, and walls. The mapping also benefits from precise distance measures provided through the Cosmicflows-1 observational program. Three-dimensional visualizations of the coherent flows of galaxies in the nearby Universe are presented, using recent results based on reconstruction of cosmic flows with the Wiener filter approach. The three major components of the Milky Way's motion, namely expulsion from the Local Void, infall toward the Virgo Cluster, and the bulk flow of the historic Local Supercluster toward the Great Attractor are illustrated using different visualization techniques and analyzed in light of the cosmography derived from the V8k redshift and Cosmicflows-1 distance catalogs.
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Daddi, E., F. Valentino, R. M. Rich, J. D. Neill, M. Gronke, D. O’Sullivan, D. Elbaz, et al. "Three Lyman-α-emitting filaments converging to a massive galaxy group at z = 2.91: discussing the case for cold gas infall." Astronomy & Astrophysics 649 (May 2021): A78. http://dx.doi.org/10.1051/0004-6361/202038700.
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We have discovered a 300 kpc-wide giant Lyman-α (Lyα) nebula centered on the massive galaxy group RO-1001 at z = 2.91 in the Cosmic Evolution Survey field. Keck Cosmic Web Imager observations reveal three cold gas filaments converging into the center of the potential well of its ∼4 × 1013 M⊙ dark matter halo, hosting 1200 M⊙ yr−1 of star formation as probed by Atacama Large Millimeter Array and NOrthern Extended Millimeter Array observations. The nebula morphological and kinematics properties and the prevalence of blueshifted components in the Lyα spectra are consistent with a scenario of gas accretion. The upper limits on active galactic nuclei activity and overall energetics favor gravity as the primary Lyα powering source and infall as the main source of gas flows to the system. Although interpretational difficulties remain, with outflows and likely also photoionization with ensuing recombination still playing a role, this finding provides arguably an ideal environment to quantitatively test models of cold gas accretion and galaxy feeding inside an actively star-forming massive halo at high redshift.
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Hopkins, Andrew. "Galaxy Metabolism." Publications of the Astronomical Society of Australia 27, no. 3 (2010): 233. http://dx.doi.org/10.1071/as10012.
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‘Galaxy Metabolism' was the second in the annual ‘Southern Cross Astrophysics Conference Series’ (http://www.aao.gov.au/AAO/southerncross/), supported by the Anglo-Australian Observatory and the Australia Telescope National Facility. It was held at the Australian National Maritime Museum in Darling Harbour, Sydney, from 22 to 26 June 2009, and was attended by 91 delegates from around the world.Over the past decade, both the star formation history and stellar mass density in galaxies spanning most of cosmic history have been well constrained. This provides the backdrop and framework within which many detailed investigations of galaxy growth are now placed. The mass-dependent and environment-dependent evolution of galaxies over cosmic history is now the focus of several surveys. Many studies are also exploring the role of gas infall and outflow in driving galaxy evolution, and the connection of these processes to massive star formation within galaxies.The aims of ‘Galaxy Metabolism’ were to bring together the global constraints on galaxy evolution, at both low and high redshift, with detailed studies of well-resolved systems, to define a clear picture of our understanding of galaxy metabolism: How do the processes of ingestion (infall), digestion (ISM physics, star formation) and excretion (outflow) govern the global properties of galaxies; how do these change over a galaxy's lifetime; and are the constraints from nearby well resolved studies consistent with those from large population surveys at low and high redshift?The conference was a great success, with an extensive variety of topics covered spanning many aspects of galaxy evolution, and brought together eloquently in a comprehensive conference summary by Warrick Couch. The four papers by De Lucia (2010), Cole (2010), Vlajić (2010) and Stocke et al. (2010) presented in this special collection of PASA are just a sampling of the depth and variety of the resentations given during the conference.
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Malavasi, Nicola, Nabila Aghanim, Hideki Tanimura, Victor Bonjean, and Marian Douspis. "Like a spider in its web: a study of the large-scale structure around the Coma cluster." Astronomy & Astrophysics 634 (January 31, 2020): A30. http://dx.doi.org/10.1051/0004-6361/201936629.
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The Cosmic Web is a complex network of filaments, walls, and voids that represent the largest structures in the Universe. In this network, which is the direct result of structure formation, galaxy clusters occupy central positions that form the nodes and these are connected by filaments. In this work, we investigate the position in the Cosmic Web of one of the most well-known and best-studied clusters of galaxies, the Coma cluster. We make use of the Sloan Digital Sky Survey Data Release 7 Main Galaxy Sample and of the Discrete Persistent Structure Extractor to detect large-scale filaments around the Coma cluster and analyse the properties of the Cosmic Web. We study the network of filaments around Coma in a region of 75 Mpc in radius. We find that the Coma cluster has a median connectivity of 2.5, in agreement with measurements from clusters of similar mass in the literature as well as with what is expected from numerical simulations. Coma is indeed connected to three secure filaments which connect it to Abell 1367 and to several other clusters in the field. The location of these filaments in the vicinity of Coma is consistent with features detected in the X-ray, as well as the likely direction of infall of galaxies, such as for example NGC 4839. The overall picture that emerges of the Coma cluster is that of a highly connected structure occupying a central position as a dense node of the Cosmic Web. We also find a tentative detection, at 2.1σ significance, of the filaments in the SZ signal.
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Sarron, F., C. Adami, F. Durret, and C. Laigle. "Pre-processing of galaxies in cosmic filaments around AMASCFI clusters in the CFHTLS." Astronomy & Astrophysics 632 (November 26, 2019): A49. http://dx.doi.org/10.1051/0004-6361/201935394.
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Context. Galaxy clusters and groups are thought to accrete material along the preferred direction of cosmic filaments. These structures have proven difficult to detect because their contrast is low, however, and only a few studies have focused on cluster infall regions. Aims. We detect cosmic filaments around galaxy clusters using photometric redshifts in the range 0.15 < z < 0.7. We characterise galaxy populations in these structures to study the influence of pre-processing by cosmic filaments and galaxy groups on star formation quenching. Methods. We detected cosmic filaments in the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) T0007 data, focusing on regions around clusters of the AMASCFI CFHTLS cluster sample. The filaments were reconstructed with the discrete persistent structure extractor (DISPERSE) algorithm in photometric redshift slices. We show that this reconstruction is reliable for a CFHTLS-like survey at 0.15 < z < 0.7 using a mock galaxy catalogue. We split our galaxy catalogue into two populations (passive and star forming) using the LePhare spectral energy density fitting algorithm and worked with two redshift bins (0.15 < z ≤ 0.4 and 0.4 < z < 0.7). Results. We showed that the AMASCFI cluster connectivity (i.e. the number of filaments that is connected to a cluster) increases with cluster mass M200. Filament galaxies outside R200 are found to be closer to clusters at low redshift, regardless of the galaxy type. Passive galaxies in filaments are closer to clusters than star-forming galaxies in the low redshift bin alone. The passive fraction of galaxies decreases with increasing clustercentric distance up to d ∼ 5 cMpc. Galaxy groups and clusters that are not located at nodes of our reconstruction are mainly found inside cosmic filaments. Conclusions. These results give clues for pre-processing in cosmic filaments that could be due to smaller galaxy groups. This trend could be further explored by applying this method to larger photometric surveys such as the Hyper Suprime-Cam Subaru Strategic Program (HSC-SPP) or Euclid.
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Hsu, Hsiang-Wen, Jürgen Schmidt, Sascha Kempf, Frank Postberg, Georg Moragas-Klostermeyer, Martin Seiß, Holger Hoffmann, et al. "In situ collection of dust grains falling from Saturn’s rings into its atmosphere." Science 362, no. 6410 (October 4, 2018): eaat3185. http://dx.doi.org/10.1126/science.aat3185.
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Saturn’s main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft’s traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We report the direct in situ detection of material from Saturn’s dense rings by the CDA impact mass spectrometer. Most detected grains are a few tens of nanometers in size and dynamically associated with the previously inferred “ring rain.” Silicate and water-ice grains were identified, in proportions that vary with latitude. Silicate grains constitute up to 30% of infalling grains, a higher percentage than the bulk silicate content of the rings.
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Kraljic, Katarina, Romeel Davé, and Christophe Pichon. "And yet it flips: connecting galactic spin and the cosmic web." Monthly Notices of the Royal Astronomical Society 493, no. 1 (January 28, 2020): 362–81. http://dx.doi.org/10.1093/mnras/staa250.
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ABSTRACT We study the spin alignment of galaxies and haloes with respect to filaments and walls of the cosmic web, identified with DisPerSE , using the Simba simulation from z = 0 − 2. Massive haloes’ spins are oriented perpendicularly to their closest filament’s axis and walls, while low-mass haloes tend to have their spins parallel to filaments and in the plane of walls. A similar mass-dependent spin flip is found for galaxies, albeit with a weaker signal particularly at low mass and low-z, suggesting that galaxies’ spins retain memory of their larger scale environment. Low-z star-forming and rotation-dominated galaxies tend to have spins parallel to nearby filaments, while quiescent and dispersion-dominated galaxies show preferentially perpendicular orientation; the star formation trend can be fully explained by the stellar mass correlation, but the morphology trend cannot. There is a dependence on HI mass, such that high-HI galaxies tend to have parallel spins while low-HI galaxies are perpendicular, suggesting that HI content may trace anisotropic infall more faithfully than the stellar component. Finally, at fixed stellar mass, the strength of spin alignments correlates with the filament’s density, with parallel alignment for galaxies in high density environments. These findings are consistent with conditional tidal torque theory, and highlight a significant correlation between galactic spin and the larger scale tides that are important e.g., for interpreting weak lensing studies. Simba allows us to rule out numerical grid locking as the cause of previously-seen low mass alignment.
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Vallés-Pérez, David, Susana Planelles, and Vicent Quilis. "Troubled cosmic flows: turbulence, enstrophy, and helicity from the assembly history of the intracluster medium." Monthly Notices of the Royal Astronomical Society 504, no. 1 (March 26, 2021): 510–27. http://dx.doi.org/10.1093/mnras/stab880.
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ABSTRACT Both simulations and observations have shown that turbulence is a pervasive phenomenon in cosmic scenarios, yet it is particularly difficult to model numerically due to its intrinsically multiscale character which demands high resolutions. Additionally, turbulence is tightly connected to the dynamical state and the formation history of galaxies and galaxy clusters, producing a diverse phenomenology which requires large samples of such structures to attain robust conclusions. In this work, we use an adaptive mesh refinement (AMR) cosmological simulation to explore the generation and dissipation of turbulence in galaxy clusters, in connection to its assembly history. We find that major mergers, and more generally accretion of gas, is the main process driving turbulence in the intracluster medium. We have especially focused on solenoidal turbulence, which can be quantified through enstrophy. Our results seem to confirm a scenario for its generation which involves baroclinicity and compression at the external (accretion) and internal (merger) shocks, followed by vortex stretching downstream of them. We have also looked at the infall of mass to the cluster beyond its virial boundary, finding that gas follows trajectories with some degree of helicity, as it has already developed some vorticity in the external shocks.
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Totani, Tomonori. "Luminosity Density Evolution in the Universe and Cosmological Parameters." Symposium - International Astronomical Union 183 (1999): 145–50. http://dx.doi.org/10.1017/s0074180900132309.
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Star formation history in galaxies is strongly correlated to their present-day colors and the Hubble sequence can be considered as a sequence of different star formation history. Therefore we can model the cosmic star formation history based on the colors of local galaxies, and comparison to direct observations of luminosity density evolution at high redshift gives a new test for the cosmological parameters which is insensitive to merger history of galaxies. The luminosity density evolution in 0 < z < 1 observed by the Canada-France Redshift Survey in three wavebands of 2800Å, 4400Å, and 1μm indicates that the Λ-dominated flat universe with λ0 ∼ 0.8 (> 0.53 at 95%CL) is strongly favored.The cosmic star formation rate (SFR) at z > 2 is also compared to the latest data of the Hubble Deep Field including new data which were not incorporated in the previous work of Totani, Yoshii, & Sato (1997), and our model of the luminosity density of spiral galaxies taking account of gas infall is consistent with the observations. Starbursts in elliptical galaxies, which are expected from the galactic wind model, however overproduce SFRs and hence they should be formed at z ≳ 5 or their UV emission has to be hidden by dust extinction. The amount of metals in galactic winds and escaping ionizing photons are enough to contaminate the Lyα forests or to reionize the universe.
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Kashibadze, Olga, Igor Karachentsev, and Valentina Karachentseva. "Dwarfs in the entourage of the Local Volume groups: flow tracers and cosmological probes." Proceedings of the International Astronomical Union 14, S344 (August 2018): 488–90. http://dx.doi.org/10.1017/s1743921318005586.
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AbstractWe consider a sample of dwarf galaxies with accurate distances and velocities around 14 massive groups in the Local Volume. We combine all the data into a single synthetic group, and then determine its radius of the zero-velocity surface, separating it against the global cosmic expansion. Our estimation is derived from fitting the the spherical infall model (including effects of the cosmological constant) to the observational data.We found the optimal value of the radius to be 0.93 ± 0.02 Mpc. Assuming the Planck model parameters, it corresponds to the total mass of the synthetic group (1.6 ± 0.2) × 1012M⊙. Thus, we obtain the paradoxical result that the total mass of the synthetic group estimated on the scale of 3–4 its virial radius is only 60% of the virial mass estimate. Anyway, we conclude that wide outskirts of the nearby groups do not contain a large amount of hidden mass outside their virial radii.
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Goerdt, Tobias. "Cold streams: detectability, relation to structure and characteristics." Proceedings of the International Astronomical Union 10, S309 (July 2014): 269–72. http://dx.doi.org/10.1017/s1743921314009843.
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AbstractCold gas streaming along the dark-matter filaments of the cosmic web is predicted to be the major provider of resources for disc buildup and star formation in massive galaxies in the early universe. We use hydrodynamical simulations to study to what extent these cold streams are traceable in the extended circum-galactic environment of galaxies via Ly alpha emission, Ly alpha absorption and selected low ionisation metal absorption lines. We predict the strength of the absorption signal produced by the streams and find that it is consistent with observations in high redshift galaxies. The characteristics of the Ly alpha emission of our simulated galaxies are similar in luminosity, morphology and extent to the observed Ly alpha blobs, with distinct kinematic features. We analyse the characteristics of the cold streams in simulations and present scaling relations for the amount of infall, its velocity, distribution and its clumpiness and compare our findings with observations.
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Bartlett, Deaglan J., Harry Desmond, Julien Devriendt, Pedro G. Ferreira, and Adrianne Slyz. "Spatially offset black holes in the Horizon-AGN simulation and comparison to observations." Monthly Notices of the Royal Astronomical Society 500, no. 4 (November 12, 2020): 4639–57. http://dx.doi.org/10.1093/mnras/staa3516.
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ABSTRACT We study the displacements between the centres of galaxies and their supermassive black holes (BHs) in the cosmological hydrodynamical simulation Horizon-AGN, and in a variety of observations from the literature. The BHs in Horizon-AGN feel a subgrid dynamical friction force, sourced by the surrounding gas, which prevents recoiling BHs being ejected from the galaxy. We find that (i) the fraction of spatially offset BHs increases with cosmic time, (ii) BHs live on prograde orbits in the plane of the galaxy with an orbital radius that decays with time but stalls near z = 0, and (iii) the magnitudes of offsets from the galaxy centres are substantially larger in the simulation than in observations. We attribute the stalling of the infall and excessive offset magnitudes to the fact that dynamical friction from stars and dark matter is not modelled in the simulation, and hence provide a way to improve the BH dynamics of future simulations.
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JAIN, DEEPAK, N. PANCHAPAKESAN, S. MAHAJAN, and V. B. BHATIA. "CONSTRAINTS ON GALAXY EVOLUTION THROUGH GRAVITATIONAL LENSING STATISTICS." Modern Physics Letters A 15, no. 01 (January 10, 2000): 41–53. http://dx.doi.org/10.1142/s0217732300000074.
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Explaining the formation and evolution of galaxies is one of the most challenging problems in observational cosmology. Many observations suggest that galaxies we see today could have evolved from the merging of smaller subsystems. Evolution of galaxies tells us how the mass or number density of the lens varies with cosmic time. Merging between the galaxies and the infall of surrounding mass into galaxies are two possible processes that can change the comoving number density of galaxies and/or their mass. We consider five different evolutionary models of galaxies. These models are: Non-evolutionary model, Guiderdoni and Volmerange model, fast merging, slow merging and mass accretion model. We study the gravitational lens image separation distribution function for these models of evolving galaxies. A comparison with data for lensed quasars taken from the HST snapshot survey rules out the fast merging model completely as this model produces a large number of small-separation lenses. It is possible that the mass accretion model and the non-evolutionary model of galaxies may be able to explain the small angle separations.
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Nasonova, O., I. Karachentsev, and V. Karachentseva. "Structure and kinematics of the Bootes filament." Proceedings of the International Astronomical Union 11, S308 (June 2014): 187–92. http://dx.doi.org/10.1017/s1743921316009820.
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AbstractBootes filament of galaxies is a dispersed chain of groups residing on sky between the Local Void and the Virgo cluster. We consider a sample of 361 galaxies inside the sky area of RA = 13h0...18h.5 and Dec = .5°... + 10° with radial velocities VLG < 2000 km/s to clarify its structure and kinematics. In this region, 161 galaxies have individual distance estimates. We use these data to draw the Hubble relation for galaxy groups, pairs as well as the field galaxies, and to examine the galaxy distribution on peculiar velocities. Our analysis exposes the known Virgo-centric infall at RA < 14h and some signs of outflow from the Local Void at RA > 17h. According to the galaxy grouping criterion, this complex contains the members of 13 groups, 11 pairs and 140 field galaxies. The most prominent group is dominated by NGC 5846. The Bootes filament contains the total stellar mass of 2.7 ×1012M⊙ and the total virial mass of 9.07×1013M⊙, having the average density of dark matter to be Ωm = 0.09, i.e. a factor three lower than the global cosmic value.
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Welker, C., Y. Dubois, C. Pichon, J. Devriendt, and N. E. Chisari. "Caught in the rhythm." Astronomy & Astrophysics 613 (May 2018): A4. http://dx.doi.org/10.1051/0004-6361/201629007.
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Context. The anisotropic distribution of satellites around the central galaxy of their host halo is both well-documented in observations and predicted by the ΛCDM model. However its amplitude, direction and possible biases associated to the specific dynamics of such satellite galaxies are still highly debated. Aims. Using the cosmological hydrodynamics simulation Horizon-AGN, we aim to quantify the anisotropy of the spatial distribution of satellite galaxies relative to their central counterpart and explore its connexion to the local cosmic web, in the redshift range between 0.3 and 0.8. Methods. Haloes and galaxies were identified and their kinematics computed using their dark matter and stellar particles respectively. Sub-haloes were discarded and galaxies lying within 5 Rvir of a given halo are matched to it. The filamentary structure of the cosmic web was extracted from the density field – smoothed over a 3 h−1 Mpc typical scale – as a network of contiguous segments. We then investigated the distribution function of relevant angles, most importantly the angle α between the central-to-satellite separation vector and the group’s nearest filament, aside with the angle between this same separation and the central minor axis. This allowed us to explore the correlations between filamentary infall, intra-cluster inspiralling and the resulting distribution of satellites around their central counterpart. Results. We find that, on average, satellites tend to be located on the galactic plane of the central object. This effect is detected for central galaxies with a stellar mass larger than 1010 M⊙ and found to be strongest for red passive galaxies, while blue galaxies exhibit a weaker trend. For galaxies with a minor axis parallel to the direction of the nearest filament, we find that the coplanarity is stronger in the vicinity of the central galaxy, and decreases when moving towards the outskirts of the host halo. By contrast, the spatial distribution of satellite galaxies relative to their closest filament follows the opposite trend: their tendency to align with them dominates at large distances from the central galaxy, and fades away in its vicinity. In that redshift range, we find hints that massive red centrals with a spin perpendicular to their filament also have corotating satellites well aligned with both the galactic plane and the filament. On the other hand, lower-mass blue centrals with a spin parallel to their filament have satellites flowing straight along this filament, and hence orthogonally to their galactic plane. The orbit of these satellites is then progressively bent towards a better alignment with the galactic plane as they penetrate the central region of their host halo. Conclusions. The kinematics previously described are consistent with satellite infall and spin build-up via quasi-polar flows, followed by a re-orientation of the spin of massive red galaxies through mergers.
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Clavico, S., S. De Grandi, S. Ghizzardi, M. Rossetti, S. Molendi, F. Gastaldello, M. Girardi, et al. "Growth and disruption in the Lyra complex." Astronomy & Astrophysics 632 (November 22, 2019): A27. http://dx.doi.org/10.1051/0004-6361/201936467.
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Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Understanding the thermodynamic properties of merging clusters can provide crucial information on how they grow in the local universe. Aims. A detailed study of the intra-cluster medium (ICM) properties of un-relaxed systems is essential to understand the fate of in-falling structures and, more generally, the virialization process. Methods. We analyzed a mosaic of XMM-Newton observations (240 ks) of the Lyra system (z ∼ 0.067) that shows a complex dynamical state. Results. We find the main cluster RXC J1825.3+3026 to be in a late merger phase, whereas its companion CIZA J1824.1+3029 is a relaxed cool-core cluster. We estimate a mass ratio of ∼1 : 2 for the pair. No diffuse X-ray emission is found in the region between them, indicating that these clusters are in a pre-merger phase. We found evidence of a galaxy group infalling on RXC J1825.3+3026 in an advanced state of disruption. The SG, one of the brightest galaxies in the Lyra complex, was very likely at the center of the infalling group. This galaxy has a gaseous “corona” indicating that it was able to retain some of its gas after the ram-pressure stripping of the intra-group medium. In this scenario the diffuse emission excess observed southwest of RXC J1825.3+3026 could be due to gas once belonging to the group and/or to cluster ICM dislocated by the passage of the group. Finally, we identified three high-velocity galaxies aligned between RXC J1825.3+3026 and the SG, two of these showing evidence of gas stripped from them during infall. We estimate them to be currently falling onto the main cluster at an infall velocity of ∼3000 km s−1. Conclusions. Our study of the Lyra complex provides important clues about the processes presiding over the virialization of massive clusters in the local Universe.
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KAMIONKOWSKI, MARC, and ANDREW H. JAFFE. "DETECTION OF GRAVITATIONAL WAVES FROM INFLATION." International Journal of Modern Physics A 16, supp01a (October 2001): 116–28. http://dx.doi.org/10.1142/s0217751x01006358.
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Recent measurements of temperature fluctuations in the cosmic microwave background (CMB) indicate that the Universe is flat and that large-scale structure grew via gravitational infall from primordial adiabatic perturbations. Both od these observations seem to indicate that we are on the right track with inflation. But what is the new physics responsible for inflation? This question can be answered with observations of the polarization of the CMB. Inflation predicts robustly the existence of a stochastic background of cosmological gravitational waves with an amplitude proportional to the square of the energy scale of inflation. This gravitational-wave background induces a unique signature in the polarization of the CMB. If inflation took place at an energy scale much smaller than that of grand unification, then the signal will be too small to be detectable. However, if inflation had something to do with grand unification or Planck-scale physics, then the signal is conceivably detectable in the optimistic case by the Planck satellite, or if not, then by a dedicated post-Planck CMB polarization experiment. Realistic developments in dector technology as well as a proper scan strategy could produce such a post-Planck experiment that would improve on Planck's sensitivity to the gravitational-wave background by several orders of magnitude in a decade timescale.
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Donnari, Martina, Annalisa Pillepich, Gandhali D. Joshi, Dylan Nelson, Shy Genel, Federico Marinacci, Vicente Rodriguez-Gomez, et al. "Quenched fractions in the IllustrisTNG simulations: the roles of AGN feedback, environment, and pre-processing." Monthly Notices of the Royal Astronomical Society 500, no. 3 (October 10, 2020): 4004–24. http://dx.doi.org/10.1093/mnras/staa3006.
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ABSTRACT We use the IllustrisTNG hydrodynamical simulations to show how the fractions of quenched galaxies vary across different environments and cosmic time, and to quantify the role AGN feedback and pre-processing play in quenching group and cluster satellites. At z = 0, we select galaxies with Mstars = 109−12 M⊙ residing within (≤R200c) massive groups and clusters of total host mass M200c = 1013−15.2 M⊙ in TNG100 and TNG300. The model predicts a quenched fraction of ∼70–90 per cent (on average) for centrals and satellites of mass ≳ 1010.5 M⊙, regardless of host mass, cosmic time (0 ≤ z ≤ 0.5), cluster-centric distance, and time since infall in the z = 0 host. Low-mass central galaxies (≲ 1010 M⊙), on the other hand, are rarely quenched unless they become members of groups (1013–14 M⊙) or clusters (≥1014 M⊙), where the quenched fraction rises to ∼ 80 per cent. Typically, the fraction of low-mass passive galaxies is higher closer to the host centre and for progressively more massive hosts. The population of low-mass satellites accreted more than ∼ 4–6 Gyr ago in massive hosts is almost entirely passive, thus suggesting an upper limit for the time needed for environmental quenching to occur. In fact, about 30 per cent of group and cluster satellites that are quenched at z = 0 were already quenched before falling into their current host, and the bulk of them quenched as early as 4–10 billion years ago. For low-mass galaxies (Mstars ≲ 1010–10.5 M⊙), this is due to pre-processing, whereby current satellites may have been members of other hosts, and hence have undergone environmental processes, before falling into their final host, this mechanism being more common and more effective for the purposes of quenching for satellites found today in more massive hosts. On the other hand, massive galaxies quench on their own and because of AGN feedback, regardless of whether they are centrals or satellites.
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Santana-Silva, L., T. S. Gonçalves, A. Basu-Zych, M. Soares-Santos, K. Menéndez-Delmestre, A. Drlica-Wagner, L. Riguccini, N. P. Kuropatkin, B. Yanny, and R. T. Eufrasio. "The environment of Lyman break analogues (ELBA) survey: star-forming galaxies in small groups." Monthly Notices of the Royal Astronomical Society 498, no. 4 (September 10, 2020): 5183–93. http://dx.doi.org/10.1093/mnras/staa2757.
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ABSTRACT The environment of Lyman break analogues survey is an imaging survey of 33 deg2 of the southern sky. The survey was observed in u, g, r, and i bands with the Dark Energy Camera on the Blanco telescope. The main goal of this project is to investigate the environment of Lyman break analogues (LBAs) low-redshift (z ∼0.2) galaxies that are remarkably similar to typical star-forming galaxies at z ∼ 3. We explore whether the environment has any influence on the observed properties of these galaxies, providing valuable insight on the formation and evolution of galaxies over cosmic time. Using the nearest neighbour method, we measure the local density of each object ranging from small to large scales (clusters of galaxies). Comparing the environment around LBAs with that of the general galaxy population in the field, we conclude that LBAs, on average, populate denser regions at small scales, but are located in similar environment to other star-forming galaxies at larger cluster-like scales. This offers evidence that nearby encounters such as mergers may influence the star formation activity in LBAs, before infall on to larger galaxy clusters. We interpret this as an indication of galaxy pre-processing, in agreement with theoretical expectations for galaxies at z ∼ 2–3 where the gravitational interactions are more intense in early formation processes of these objects.
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Wright, Ruby J., Claudia del P. Lagos, Chris Power, and Peter D. Mitchell. "The impact of stellar and AGN feedback on halo-scale baryonic and dark matter accretion in the eagle simulations." Monthly Notices of the Royal Astronomical Society 498, no. 2 (August 14, 2020): 1668–92. http://dx.doi.org/10.1093/mnras/staa2359.
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ABSTRACT We use the eagle suite of hydrodynamical simulations to analyse accretion rates (and the breakdown of their constituent channels) on to haloes over cosmic time, comparing the behaviour of baryons and dark matter (DM). We also investigate the influence of sub-grid baryon physics on halo-scale inflow, specifically the consequences of modelling radiative cooling, as well as feedback from stars and active galactic nuclei (AGNs). We find that variations in halo baryon fractions at fixed mass (particularly their circumgalactic medium gas content) are very well correlated with variations in the baryon fraction of accreting matter, which we show to be heavily suppressed by stellar feedback in low-mass haloes, Mhalo ≲ 1011.5 M⊙. Breaking down accretion rates into first infall, recycled, transfer, and merger components, we show that baryons are much more likely to be smoothly accreted than to have originated from mergers when compared to DM, finding (averaged across halo mass) a merger contribution of $\approx 6{{\ \rm per\ cent}}$ for baryons, and $\approx 15{{\ \rm per\ cent}}$ for DM at z ≈ 0. We also show that the breakdown of inflow into different channels is strongly dependent on sub-grid physics, particularly the contribution of recycled accretion (accreting matter that has been previously ejected from progenitor haloes). Our findings highlight the dual role that baryonic feedback plays in regulating the evolution of galaxies and haloes: by (i) directly removing gas from haloes, and (ii) suppressing gas inflow to haloes.
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Ruffle, Paul, Tom Millar, Helen Roberts, Don Lubowich, and Christian Henkel. "Molecular line observations and chemical modelling of galactic edge clouds." Proceedings of the International Astronomical Union 4, S251 (February 2008): 145–46. http://dx.doi.org/10.1017/s1743921308021418.
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AbstractEdge Clouds 1 and 2 (EC1 and EC2) are large molecular clouds with the largest galactocentric distances known to exist in the Milky Way. We present observations of these clouds and use them to determine physical characteristics. For EC2 we calculate a gas temperature of 20 K and a density ofn(H2) ~ 104cm−3. Based on our CO maps, we estimate the mass of EC2 at around 104M⊙, and continuum observations suggest a dust-to-gas mass ratio as low as 0.001. Chemical models have been developed to reproduce the abundances in EC2 and they indicate that: heavy element abundances may be reduced by a factor of five relative to the solar neighbourhood (similar to dwarf irregular galaxies and damped Lyman alpha systems); very low extinction (AV< 4 mag) due to a very low dust-to-gas ratio; an enhanced cosmic ray ionisation rate; and a higher UV field compared to local interstellar values. The reduced abundances may be attributed to the low level of star formation in this region and are probably also related to the continuing infall of low metallicity halo gas since the Milky Way formed. We find that shocks from an old supernova remnant may have determined the morphology and dynamics of EC2, including the recently discovered star clusters embedded in the northern and southern cores. However, compared to EC2, EC1 appears to be a chemically less varied environment. The apparent molecule-poor nature of EC1 demonstrates the characteristics of clouds that have not had the benefit of SN shocks to stimulate an active cloud chemistry and star formation.
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Hoffman, Yehuda, Adi Nusser, Aurélien Valade, Noam I. Libeskind, and R. Brent Tully. "From Cosmicflows distance moduli to unbiased distances and peculiar velocities." Monthly Notices of the Royal Astronomical Society 505, no. 3 (June 17, 2021): 3380–92. http://dx.doi.org/10.1093/mnras/stab1457.
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ABSTRACT Surveys of galaxy distances and radial peculiar velocities can be used to reconstruct the large-scale structure. Other than systematic errors in the zero-point calibration of the galaxy distances the main source of uncertainties of such data is errors on the distance moduli, assumed here to be Gaussian and thus turning into lognormal errors on distances and velocities. Naively treated, this leads to spurious nearby outflow and strong infall at larger distances. The lognormal bias is corrected here and tested against mock data extracted from a ΛCDM simulation, designed to statistically follow the grouped Cosmicflows-3 (CF3) data. Considering a subsample of data points, all of which have the same true distances or the same redshifts, the lognormal bias arises because the means of the distributions of observed distances and velocities are skewed off the means of the true distances and velocities. However, the medians are invariant under the lognormal transformation. This invariance allows the Gaussianization of the distances and velocities and the removal of the lognormal bias. This bias Gaussianization correction (BGc) algorithm is tested against mock CF3 catalogues. The test consists of a comparison of the BGc estimated with the simulated distances and velocities and of an examination of the Wiener filter reconstruction from the BGc data. Indeed, the BGc eliminates the lognormal bias. The estimation of Hubble’s constant (H0) is also tested. The residual of the BGc-estimated H0 from the simulated values is $-0.6\pm 0.7{\, \rm km \ s^{-1}\, Mpc^{-1}}$, and is dominated by the cosmic variance. The BGc correction of the actual CF3 data yields $H_0=75.8\pm 1.1{\, \rm km \ s^{-1}\, Mpc^{-1}}$.
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Behroozi, Peter, Risa H. Wechsler, Andrew P. Hearin, and Charlie Conroy. "UniverseMachine: The correlation between galaxy growth and dark matter halo assembly from z = 0−10." Monthly Notices of the Royal Astronomical Society 488, no. 3 (May 2, 2019): 3143–94. http://dx.doi.org/10.1093/mnras/stz1182.
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ABSTRACTWe present a method to flexibly and self-consistently determine individual galaxies’ star formation rates (SFRs) from their host haloes’ potential well depths, assembly histories, and redshifts. The method is constrained by galaxies’ observed stellar mass functions, SFRs (specific and cosmic), quenched fractions, ultraviolet (UV) luminosity functions, UV–stellar mass relations, IRX–UV relations, auto- and cross-correlation functions (including quenched and star-forming subsamples), and quenching dependence on environment; each observable is reproduced over the full redshift range available, up to 0 < z < 10. Key findings include the following: galaxy assembly correlates strongly with halo assembly; quenching correlates strongly with halo mass; quenched fractions at fixed halo mass decrease with increasing redshift; massive quenched galaxies reside in higher-mass haloes than star-forming galaxies at fixed galaxy mass; star-forming and quenched galaxies’ star formation histories at fixed mass differ most at z < 0.5; satellites have large scatter in quenching time-scales after infall, and have modestly higher quenched fractions than central galaxies; Planck cosmologies result in up to 0.3 dex lower stellar – halo mass ratios at early times; and, none the less, stellar mass–halo mass ratios rise at z > 5. Also presented are revised stellar mass – halo mass relations for all, quenched, star-forming, central, and satellite galaxies; the dependence of star formation histories on halo mass, stellar mass, and galaxy SSFR; quenched fractions and quenching time-scale distributions for satellites; and predictions for higher-redshift galaxy correlation functions and weak lensing surface densities. The public data release (DR1) includes the massively parallel (>105 cores) implementation (the UniverseMachine), the newly compiled and remeasured observational data, derived galaxy formation constraints, and mock catalogues including lightcones.
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Zu, Ying. "Kinematics of Mg ii absorbers from the redshift-space distortion around massive quiescent galaxies." Monthly Notices of the Royal Astronomical Society 506, no. 1 (June 21, 2021): 115–27. http://dx.doi.org/10.1093/mnras/stab1752.
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ABSTRACT The kinematics of Mg ii absorbers is the key to understanding the origin of cool, metal-enriched gas clouds in the circumgalactic medium of massive quiescent galaxies. Exploiting the fact that the cloud line-of-sight velocity distribution is the only unknown for predicting the redshift-space distortion (RSD) of Mg ii absorbers from their 3D real-space distribution around galaxies, we develop a novel method to infer the cool cloud kinematics from the redshift-space galaxy–cloud cross-correlation ξs. We measure ξs for ∼104 Mg ii absorbers around ∼8 × 105 CMASS galaxies at 0.4 < z < 0.8. We discover that ξs does not exhibit a strong Fingers-of-God effect, but is heavily truncated at velocity ${\sim }300\, \mathrm{km}\, {\rm s}^{-1}$. We reconstruct both the redshift and real-space cloud number density distributions inside haloes, $\xi ^{s}_{1h}$ and ξ1h, respectively. Thus, for any model of cloud kinematics, we can predict $\xi ^{s}_{1h}$ from the reconstructed ξ1h, and self-consistently compare to the observed $\xi ^{s}_{1h}$. We consider four types of cloud kinematics, including an isothermal model with a single velocity dispersion, a satellite infall model in which cool clouds reside in the subhaloes, a cloud accretion model in which clouds follow the cosmic gas accretion, and a tired wind model in which clouds originate from the galactic wind-driven bubbles. All the four models provide statistically good fits to the RSD data, but only the tired wind model can reproduce the observed truncation by propagating ancient wind bubbles at ${\sim }250\, \mathrm{km}\, s^{-1}$ on scales ${\sim }400\, \, h^{-1}\, \mathrm{kpc}$. Our method provides an exciting path to decoding the dynamical origin of metal absorbers from the RSD measurements with upcoming spectroscopic surveys.
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Gallazzi, Anna R., A. Pasquali, S. Zibetti, and F. La Barbera. "Galaxy evolution across environments as probed by the ages, stellar metallicities, and [α /Fe] of central and satellite galaxies." Monthly Notices of the Royal Astronomical Society 502, no. 3 (February 3, 2021): 4457–78. http://dx.doi.org/10.1093/mnras/stab265.
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ABSTRACT We explore how the star formation and metal enrichment histories of present-day galaxies have been affected by environment combining stellar population parameter estimates and group environment characterization for SDSS DR7. We compare stellar ages, stellar metallicities, and crucially, element abundance ratios $\rm [\alpha /Fe]$ of satellite and central galaxies, as a function of their stellar and host group halo mass, controlling for the current star formation rate and for the infall epoch. We confirm that below M* ∼ 1010.5 M⊙ satellites are older and slightly metal richer than equally massive central galaxies. In contrast, we do not detect any difference in their $\rm [\alpha /Fe]$: $\rm [\alpha /Fe]$ depends primarily on stellar mass and not on group hierarchy nor host halo mass. We also find that the differences in the median age and metallicity of satellites and centrals at stellar mass below $\rm 10^{10.5}\,M_\odot$ are largely due to the higher fraction of passive galaxies among satellites and as a function of halo mass. We argue that the observed trends at low masses reveal the action of satellite-specific environmental effects in a ‘delayed-then-rapid’ fashion. When accounting for the varying quiescent fraction, small residual excess in age, metallicity and $\rm [\alpha /Fe]$ emerge for satellites dominated by old stellar populations and residing in haloes more massive than 1014 M⊙, compared to equally massive central galaxies. This excess in age, metallicity, and $\rm [\alpha /Fe]$ pertain to ancient infallers, i.e. satellites that have accreted on to the current halo more than 5 Gyr ago. This result points to the action of environment in the early phases of star formation in galaxies located close to cosmic density peaks.
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Einasto, Maret, Boris Deshev, Heidi Lietzen, Rain Kipper, Elmo Tempel, Changbom Park, Mirt Gramann, Pekka Heinämäki, Enn Saar, and Jaan Einasto. "Infalling groups and galaxy transformations in the cluster A2142." Astronomy & Astrophysics 610 (February 2018): A82. http://dx.doi.org/10.1051/0004-6361/201731600.
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Context. Superclusters of galaxies provide dynamical environments for the study of the formation and evolution of structures in the cosmic web from galaxies, to the richest galaxy clusters, and superclusters themselves. Aims. We study galaxy populations and search for possible merging substructures in the rich galaxy cluster A2142 in the collapsing core of the supercluster SCl A2142, which may give rise to radio and X-ray structures in the cluster, and affect galaxy properties of this cluster. Methods. We used normal mixture modelling to select substructure of the cluster A2142. We compared alignments of the cluster, its brightest galaxies (hereafter BCGs), subclusters, and supercluster axes. The projected phase space (PPS) diagram and clustercentric distributions are used to analyse the dynamics of the cluster and study the distribution of various galaxy populations in the cluster and subclusters. Results. We find several infalling galaxy groups and subclusters. The cluster, supercluster, BCGs, and one infalling subcluster are all aligned. Their orientation is correlated with the alignment of the radio and X-ray haloes of the cluster. Galaxy populations in the main cluster and in the outskirts subclusters are different. Galaxies in the centre of the main cluster at the clustercentric distances 0.5 h−1 Mpc (Dc∕Rvir < 0.5, Rvir = 0.9 h−1 Mpc) have older stellar populations (with the median age of 10−11 Gyr) than galaxies at larger clustercentric distances. Star-forming and recently quenched galaxies are located mostly at the clustercentric distances Dc ≈ 1.8 h−1 Mpc, where subclusters fall into the cluster and the properties of galaxies change rapidly. In this region the median age of stellar populations of galaxies is about 2 Gyr. Galaxies in A2142 on average have higher stellar masses, lower star formation rates, and redder colours than galaxies in rich groups. The total mass in infalling groups and subclusters is M ≈ 6 × 1014 h−1 M⊙, that is approximately half of the mass of the cluster. This mass is sufficient for the mass growth of the cluster from redshift z = 0.5 (half-mass epoch) to the present. Conclusions. Our analysis suggests that the cluster A2142 has formed as a result of past and present mergers and infallen groups, predominantly along the supercluster axis. Mergers cause complex radio and X-ray structure of the cluster and affect the properties of galaxies in the cluster, especially at the boundaries of the cluster in the infall region. Explaining the differences between galaxy populations, mass, and richness of A2142, and other groups and clusters may lead to better insight about the formation and evolution of rich galaxy clusters.
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Beckman, John, Peter Erwin, and Leonel Gutiérrez. "What Disc Brightness Profiles Can Tell us about Galaxy Evolution." Proceedings of the International Astronomical Union 10, H16 (August 2012): 361. http://dx.doi.org/10.1017/s1743921314011338.
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AbstractAzimuthally averaged surface brightness profiles of disc galaxies provide a most useful practical classification scheme which gives insights into their evolution. Freeman (1970) first classified disc profiles into Type I, with a single exponential decline in surface brightness, and Type II, having a split exponential profile, whose inner radial portion is shallower than its outer section. Van der Kruit & and Searle, (1981) drew attention to sharply truncated profiles of outer discs observed edge-on, but more recently Pohlen et al. (2004) showed that if these same galaxies were observed face-on their profiles would be of Type II. Finally in Erwin, Beckman and Pohlen (2005) we found a significant fraction of profiles with inner portion steeper than the outer portion, which we termed “antitruncations“ or Type III profiles. In Erwin, Pohlen and Beckman (2008), we produced a refined classification, taking into account those Type II's produced by dynamical effects at the outer Lindblad resonance, and those Type III's caused by the presence of an outer stellar halo. In Gutiérrez et al. (2011) we showed the distribution of the three main profile types along the Hubble sequence. In early type discs Types I and III predominate, while in late types, Sc and later, Type II predominates.The evolution of Type II's over cosmic time was studied by Azzollini et al. (2008a, 2008b) who obtained four key results: (a) between z = 1 and z = 0 the break radius between the inner (shallower) and outer (steeper) profile has increased systematically, by a factor 1.3; (b) the inner profile has steepened while the outer profile is shallower at lower z; (c) the extrapolated central surface brightness has fallen by over two magnitudes; (d) the discs in the full redshift interval are always bluest at the break radius. While this behaviour can be qualitatively explained via evolutionary models including stellar migration plus gas infall, such as that by Roskar et al. (2008), and while Type III profiles may have a qualitative explanation via mergers and/or accretion, the widespread existence of Type I's is still a major conceptual challenge.
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Babichev, Eugeny, Philippe Brax, Chiara Caprini, Jérôme Martin, and Danièle A. Steer. "Dirac Born Infeld (DBI) cosmic strings." Journal of High Energy Physics 2009, no. 03 (March 13, 2009): 091. http://dx.doi.org/10.1088/1126-6708/2009/03/091.
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Ikrima, Ika, Handhika S. Ramadhan, and Terry Mart. "Cosmic String Global Superconducting Dirac Born Infeld." Journal of Physics: Conference Series 739 (August 2016): 012061. http://dx.doi.org/10.1088/1742-6596/739/1/012061.
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Ferraro, Rafael, and Franco Fiorini. "The regular cosmic string in Born-Infeld gravity." Journal of Physics: Conference Series 314 (September 22, 2011): 012114. http://dx.doi.org/10.1088/1742-6596/314/1/012114.
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Narayanan, Desika, and Chris Carilli. "A cosmic growth spurt in an infant galaxy." Nature 496, no. 7445 (April 2013): 303–4. http://dx.doi.org/10.1038/496303a.
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Lee, Ha-Na, Kwang-Ho Kwon, and Jin-Koo Kim. "Progressive Collapse Resisting Capacity of Building Structures with Infill Steel Panels." Journal of the Computational Structural Engineering Institute of Korea 25, no. 1 (February 29, 2012): 19–26. http://dx.doi.org/10.7734/coseik.2012.25.1.019.
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Capozziello, Salvatore, Mariafelicia De Laurentis, and Ratbay Myrzakulov. "Noether symmetry approach for Dirac–Born–Infeld cosmology." International Journal of Geometric Methods in Modern Physics 12, no. 05 (May 2015): 1550065. http://dx.doi.org/10.1142/s0219887815500656.
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We consider the Noether Symmetry Approach for a cosmological model derived from a tachyon scalar field T with a Dirac–Born–Infeld Lagrangian and a potential V(T). Furthermore, we assume a coupled canonical scalar field ϕ with an arbitrary interaction potential B(T, ϕ). Exact solutions are derived consistent with the accelerated behavior of cosmic fluid.
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Cruz, N. M. Jiménez, and Celia Escamilla-Rivera. "Dynamical cosmologies in Eddington-inspired-Born–Infeld theory." International Journal of Modern Physics D 28, no. 15 (November 2019): 1950167. http://dx.doi.org/10.1142/s0218271819501670.
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In this paper, we study the cosmological evolution of the universe filled with a perfect fluid in the Eddington-inspired-Born–Infeld gravity. Applying an alternative method in which the evolution of the scale factor for this theory is linked to the cosmographic parameters, we obtain a dynamical dark energy solution where the singularity (through a regular bounce or a loitering phase) still can be avoided for [Formula: see text] with [Formula: see text]. For the range [Formula: see text], the results lead us to universes that experience an unlimited rate of expansion with finite density. Also, we obtain a possible maximum value of [Formula: see text] at the cosmic bounce point.
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Holt, Ewa M. "Estimating the mass of cosmic rays by combining radio and muon measurements." EPJ Web of Conferences 216 (2019): 02002. http://dx.doi.org/10.1051/epjconf/201921602002.
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The Auger Engineering Radio Array (AERA) is a radio detector at the Pierre Auger Observatory and it is dedicated to measure the radio emission of cosmic-ray air showers. AERA is co-located with the underground muon detectors of the Auger Muons and Infill for the Ground Array (AMIGA). This provides a perfect setup to experimentally test the benefits of combining muons and radio emission for estimating the primary mass. We have investigated this combination using air-shower simulations. We compared the performance for mass separation of this new method to alternative methods in which the electrons and muons are measured with particle detectors at the surface. Forshowers with zenith angles below 50° the new method is of comparable performance, and for showers more inclinedthan 50° it is clearly superior. Therefore, measuring the radio signal in addition to the muons significantly improves the mass sensitivity compared to techniques using solely particle measurements.
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DeYOUNG, TYCE. "NEUTRINO ASTRONOMY WITH ICECUBE." Modern Physics Letters A 24, no. 20 (June 28, 2009): 1543–57. http://dx.doi.org/10.1142/s0217732309031417.
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IceCube is a kilometer-scale high energy neutrino telescope under construction at the South Pole, a second-generation instrument expanding the capabilities of the AMANDA telescope. The scientific portfolio of IceCube includes the detection of neutrinos from astrophysical objects such as the sources of the cosmic rays, the search for dark matter, and fundamental physics using a very large data set of atmospheric neutrinos. The design and status of IceCube are briefly reviewed, followed by a summary of results to date from AMANDA and initial IceCube results from the 2007 run, with 22 of a planned 86 strings operational. The new infill array known as Deep Core, which will extend IceCube's capabilities to energies as low as 10 GeV, is also described.