Articoli di riviste: "Stellar feedbacks"

1

Ciardi, B. "Inhomogeneous reionization regulated by radiative and stellar feedbacks". Astronomical & Astrophysical Transactions 20, n. 1 (giugno 2001): 177–82. http://dx.doi.org/10.1080/10556790108208210.

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2

Ekström, Sylvia, Georges Meynet, Cyril Georgy, José Groh, Arthur Choplin e Hanfeng Song. "Massive star evolution: feedbacks in low-Z environment". Proceedings of the International Astronomical Union 14, S344 (agosto 2018): 153–60. http://dx.doi.org/10.1017/s1743921318007238.

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AbstractMassive stars are the drivers of the chemical evolution of dwarf galaxies. We review here the basics of massive star evolution and the specificities of stellar evolution in low-Z environment. We discuss nucleosynthetic aspects and what observations could constrain our view on the first generations of stars.

3

Ciardi, B., A. Ferrara, F. Governato e A. Jenkins. "Inhomogeneous reionization of the intergalactic medium regulated by radiative and stellar feedbacks". Monthly Notices of the Royal Astronomical Society 314, n. 3 (21 maggio 2000): 611–29. http://dx.doi.org/10.1046/j.1365-8711.2000.03365.x.

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4

Dekel, Avishai, Nir Mandelker, Frederic Bournaud, Daniel Ceverino, Yicheng Guo e Joel Primack. "Clump survival and migration in VDI galaxies: an analytical model versus simulations and observations". Monthly Notices of the Royal Astronomical Society 511, n. 1 (14 gennaio 2022): 316–40. http://dx.doi.org/10.1093/mnras/stab3810.

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ABSTRACT We address the nature of the giant clumps in high-z galaxies that undergo violent disc instability, distinguishing between long-lived and short-lived clumps. We study the evolution of long-lived clumps during migration through the disc via an analytical model tested by simulations and confront theory with CANDELS-HST observations. The clump ‘bathtub’ model, which considers gas and stellar gain and loss, involves four parameters: the accretion efficiency α, the star formation rate (SFR) efficiency ϵd, and the outflow mass-loading factors for gas and stars, η and ηs. The corresponding time-scales are comparable to the migration time, two-three orbital times. The accretion-rate dependence on clump mass, gas, and stars, allows an analytical solution involving exponential growing and decaying modes. For the fiducial parameter values there is a main evolution phase where the SFR and gas mass are constant and the stellar mass is rising linearly with time. This makes the inverse specific SFR an observable proxy for clump age. When η or ϵd are high, or α is low, the decaying mode induces a decline of SFR and gas mass till the migration ends. Later, the masses and SFR approach an hypothetical exponential growth with a constant specific SFR. The model matches simulations with different, moderate feedbacks, both in isolated and cosmological settings. The observed clumps agree with our predictions, indicating that the massive clumps are long-lived and migrating. A challenge is to model feedback that is non-disruptive in massive clumps but suppresses SFR to match the galactic stellar-to-halo mass ratio.

5

Locci, Daniele, Antonino Petralia, Giuseppina Micela, Antonio Maggio, Angela Ciaravella e Cesare Cecchi-Pestellini. "Extreme-ultraviolet- and X-Ray-driven Photochemistry of Gaseous Exoplanets". Planetary Science Journal 3, n. 1 (1 gennaio 2022): 1. http://dx.doi.org/10.3847/psj/ac3f3c.

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Abstract The interaction of exoplanets with their host stars causes a vast diversity in bulk and atmospheric compositions and physical and chemical conditions. Stellar radiation, especially at the shorter wavelengths, drives the chemistry in the upper atmospheric layers of close orbiting gaseous giants, providing drastic departures from equilibrium. In this study, we aim at unfolding the effects caused by photons in different spectral bands on the atmospheric chemistry. This task is particularly difficult because the characteristics of chemical evolution emerge from many feedbacks on a wide range of timescales, and because of the existing correlations among different portions of the stellar spectrum. In describing the chemistry, we have placed particular emphasis on the molecular synthesis induced by X-rays. The weak X-ray photoabsorption cross sections of the atmospheric constituents boost the gas ionization to pressures inaccessible to vacuum and extreme-ultraviolet photons. Although X-rays interact preferentially with metals, they produce a secondary electron cascade able to ionize efficiently hydrogen- and helium-bearing species, giving rise to a distinctive chemistry.

6

Fierlinger, Katharina M., Andreas Burkert, Evangelia Ntormousi, Peter Fierlinger, Marc Schartmann, Alessandro Ballone, Martin G. H. Krause e Roland Diehl. "Stellar feedback efficiencies: supernovae versus stellar winds". Monthly Notices of the Royal Astronomical Society 456, n. 1 (17 dicembre 2015): 710–30. http://dx.doi.org/10.1093/mnras/stv2699.

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7

Forget, F., e J. Leconte. "Possible climates on terrestrial exoplanets". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, n. 2014 (28 aprile 2014): 20130084. http://dx.doi.org/10.1098/rsta.2013.0084.

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What kind of environment may exist on terrestrial planets around other stars? In spite of the lack of direct observations, it may not be premature to speculate on exoplanetary climates, for instance, to optimize future telescopic observations or to assess the probability of habitable worlds. To begin with, climate primarily depends on (i) the atmospheric composition and the volatile inventory; (ii) the incident stellar flux; and (iii) the tidal evolution of the planetary spin, which can notably lock a planet with a permanent night side. The atmospheric composition and mass depends on complex processes, which are difficult to model: origins of volatiles, atmospheric escape, geochemistry, photochemistry, etc. We discuss physical constraints, which can help us to speculate on the possible type of atmosphere, depending on the planet size, its final distance for its star and the star type. Assuming that the atmosphere is known, the possible climates can be explored using global climate models analogous to the ones developed to simulate the Earth as well as the other telluric atmospheres in the solar system. Our experience with Mars, Titan and Venus suggests that realistic climate simulators can be developed by combining components, such as a ‘dynamical core’, a radiative transfer solver, a parametrization of subgrid-scale turbulence and convection, a thermal ground model and a volatile phase change code. On this basis, we can aspire to build reliable climate predictors for exoplanets. However, whatever the accuracy of the models, predicting the actual climate regime on a specific planet will remain challenging because climate systems are affected by strong positive feedbacks. They can drive planets with very similar forcing and volatile inventory to completely different states. For instance, the coupling among temperature, volatile phase changes and radiative properties results in instabilities, such as runaway glaciations and runaway greenhouse effect.

8

Herbst, Konstantin, John Lee Grenfell, Miriam Sinnhuber, Heike Rauer, Bernd Heber, Saša Banjac, Markus Scheucher et al. "A new model suite to determine the influence of cosmic rays on (exo)planetary atmospheric biosignatures". Astronomy & Astrophysics 631 (31 ottobre 2019): A101. http://dx.doi.org/10.1051/0004-6361/201935888.

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Context. The first opportunity to detect indications for life outside of the Solar System may be provided already within the next decade with upcoming missions such as the James Webb Space Telescope (JWST), the European Extremely Large Telescope (E-ELT) and the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, searching for atmospheric biosignatures on planets in the habitable zone of cool K- and M-stars. Nevertheless, their harsh stellar radiation and particle environment could lead to photochemical loss of atmospheric biosignatures. Aims. We aim to study the influence of cosmic rays on exoplanetary atmospheric biosignatures and the radiation environment considering feedbacks between energetic particle precipitation, climate, atmospheric ionization, neutral and ion chemistry, and secondary particle generation. Methods. We describe newly combined state-of-the-art modeling tools to study the impact of the radiation and particle environment, in particular of cosmic rays, on atmospheric particle interaction, atmospheric chemistry, and the climate-chemistry coupling in a self-consistent model suite. To this end, models like the Atmospheric Radiation Interaction Simulator (AtRIS), the Exoplanetary Terrestrial Ion Chemistry model (ExoTIC), and the updated coupled climate-chemistry model are combined. Results. In addition to comparing our results to Earth-bound measurements, we investigate the ozone production and -loss cycles as well as the atmospheric radiation dose profiles during quiescent solar periods and during the strong solar energetic particle event of February 23, 1956. Further, the scenario-dependent terrestrial transit spectra, as seen by the NIR-Spec infrared spectrometer onboard the JWST, are modeled. Amongst others, we find that the comparatively weak solar event drastically increases the spectral signal of HNO3, while significantly suppressing the spectral feature of ozone. Because of the slow recovery after such events, the latter indicates that ozone might not be a good biomarker for planets orbiting stars with high flaring rates.

9

D'Antona, Francesca. "Stellar evolution and feedback connections to stellar dynamics". Proceedings of the International Astronomical Union 2, n. 14 (agosto 2006): 430–31. http://dx.doi.org/10.1017/s1743921307011222.

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AbstractUntil a few years ago, the common paradigm for the formation of Globular Clusters (GCs) was that they constitute a ‘simple stellar population’ in which all the stars were formed from a chemically homogeneous cluster medium within a relatively short interval of time, at the beginning of the galactic life. In recent years, the spectroscopic information on the low luminosity (turnoff) cluster stars have extended to the unevolved stars the recognition that chemical anomalies are a common feature of GCs and not an exception. This has provoked a revolution in the simple view of GC formation, and requires an adequate dynamical modelling including gas dynamics. It is by now well accepted that at least two different stellar components are common in most GCs. These are almost unequivocally identified with (i) a first stellar generation, which gave origin to stars of all masses; and (ii)) a second generation, born from the ejecta of the most massive asymptotic giant branch stars of the first generation, in the first 100–200 Myr from the first burst of star formation. A ‘third’ population is present only in some GCs, and is more difficult to be understood. It is characterized by stars having a huge helium content (Y ≃ 0.4, if stellar modelling is reasonable) and extreme chemical anomalies in the proton capture elements (Na, O, Al). The status of understanding of the GC properties, based on our most recent models of stellar evolution, is discussed.

10

Ivanova, Nataliya M. "Stellar dynamics and feedback connections to stellar evolution". Proceedings of the International Astronomical Union 2, n. 14 (agosto 2006): 432–33. http://dx.doi.org/10.1017/s1743921307011234.

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AbstractIn dense stellar systems, dynamical interactions between objects inevitably lead to frequent formation of exotic stellar objects and multiple systems, thereby imposing new questions for the stellar evolution theory. The evolutionary path of such systems could be different from that of the unperturbed objects, therefore, we must re-evaluate their evolutionary treatment to clarify their consequent dynamical evolution. We review briefly the classes of important dynamical encounters and discuss several post-encounter outcomes that may require more detailed attention or development of a new treatment in stellar evolution: evolution of complex merger products, spun-up stars, binaries with stripped giants and triples.

11

Raju, Aman N., Dávid Guszejnov e Stella S. R. Offner. "Stellar Multiplicity in an RMHD Simulation with Stellar Feedback". Research Notes of the AAS 5, n. 7 (20 luglio 2021): 164. http://dx.doi.org/10.3847/2515-5172/ac151e.

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12

Woods, Paul. "Feedback gets a stellar review". Nature Astronomy 6, n. 4 (aprile 2022): 413. http://dx.doi.org/10.1038/s41550-022-01672-5.

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13

Swartz, W. H., R. S. Stolarski, L. D. Oman, E. L. Fleming e C. H. Jackman. "Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model". Atmospheric Chemistry and Physics Discussions 12, n. 3 (8 marzo 2012): 7039–71. http://dx.doi.org/10.5194/acpd-12-7039-2012.

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Abstract. The 11-yr solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOS CCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3–6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 – 3 times larger than the simulation using the NRL SSI. The GEOS CCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) and Spectral Irradiance Monitor (SIM) on SORCE, respectively. A higher wavelength-resolution analysis of the spectral response could allow for a better prediction of the atmospheric response to arbitrary SSI variations.

14

Tillman, Megan Taylor, Blakesley Burkhart, Stephanie Tonnesen, Simeon Bird, Greg L. Bryan, Daniel Anglés-Alcázar, Sultan Hassan et al. "An Exploration of AGN and Stellar Feedback Effects in the Intergalactic Medium via the Low-redshift Lyα Forest". Astronomical Journal 166, n. 6 (7 novembre 2023): 228. http://dx.doi.org/10.3847/1538-3881/ad02f5.

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Abstract We explore the role of galactic feedback on the low-redshift Lyα (Lyα) forest (z ≲ 2) statistics and its potential to alter the thermal state of the intergalactic medium. Using the Cosmology and Astrophysics with Machine Learning Simulations (CAMELS) suite, we explore variations of the AGN and stellar feedback models in the IllustrisTNG and Simba subgrid models. We find that both AGN and stellar feedback in Simba play a role in setting the Lyα forest column density distribution function (CDD) and the Doppler width (b-value) distribution. The Simba AGN jet feedback mode is able to efficiently transport energy out to the diffuse IGM, causing changes in the shape and normalization of the CDD and a broadening of the b-value distribution. We find that stellar feedback plays a prominent role in regulating supermassive black hole growth and feedback, highlighting the importance of constraining stellar and AGN feedback simultaneously. In IllustrisTNG, the AGN feedback variations explored in CAMELS do not affect the Lyα forest, but varying the stellar feedback model does produce subtle changes. Our results imply that the low-z Lyα forest can be sensitive to changes in the ultraviolet background, stellar and black hole feedback, and that AGN jet feedback in particular can have a strong effect on the thermal state of the IGM.

15

Ceverino, Daniel, e Anatoly Klypin. "The role of stellar feedback in the formation of galactic disks and bulges in a ΛCDM Universe". Proceedings of the International Astronomical Union 3, S245 (luglio 2007): 33–34. http://dx.doi.org/10.1017/s1743921308017213.

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AbstractAlthough supernova explosions and stellar winds happens at scales bellow 100 pc, they affect the interstellar medium (ISM) and galaxy formation. We use cosmological N-body+Hydrodynamics simulations of galaxy formation, as well as simulations of the ISM to study the effect of stellar feedback on galactic scales. Stellar feedback maintains gas with temperatures above a million degrees. This gas fills bubbles, super-bubbles and chimneys. Our model of feedback, in which 10%–30% of the feedback energy is coming from runaway stars, reproduces this hot gas only if the resolution is better than 50 pc. This is 10 times better than the typical resolution in cosmological simulations of galaxy formation. Only with this resolution, the effect of stellar feedback in galaxy formation is resolved without any assumption about sub-resolution physics. Stellar feedback can regulate the formation of bulges and can shape the inner parts of the rotation curve.

16

Berentzen, Ingo, Isaac Shlosman, Inma Martinez‐Valpuesta e Clayton H. Heller. "Gas Feedback on Stellar Bar Evolution". Astrophysical Journal 666, n. 1 (settembre 2007): 189–200. http://dx.doi.org/10.1086/520531.

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17

Palouš, Jan, Richard Wünsch, James E. Dale, Vojtěch Sidorin e Anthony Whitworth. "Stellar feedback and triggered star formation". Proceedings of the International Astronomical Union 5, S266 (agosto 2009): 41–45. http://dx.doi.org/10.1017/s1743921309990858.

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AbstractYoung, massive stars influence their ambient medium through winds and radiation. The outcome of this feedback depends on the number of massive stars in a star cluster and on the density of the ambient medium. This contribution is based on a comparison of observations to the results of numerical simulations. We discuss the gravitational fragmentation of feedback-driven shells expanding from young stellar clusters. The thin-shell approximation is compared to 3D hydrodynamical simulations with smoothed-particle hydrodynamics and adaptive-mesh refinement codes. We explore the influence of external pressure and propose a thick-shell dispersion relation, where the pressure of the external medium is included. The mass spectrum of the shell fragments is constructed and we speculate about the origin of the deficit of low-mass objects.

18

Mashchenko, S., J. Wadsley e H. M. P. Couchman. "Stellar Feedback in Dwarf Galaxy Formation". Science 319, n. 5860 (11 gennaio 2008): 174–77. http://dx.doi.org/10.1126/science.1148666.

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19

Fabian, A. C. "Cosmic Feedback from AGN". Proceedings of the International Astronomical Union 5, S267 (agosto 2009): 341–49. http://dx.doi.org/10.1017/s1743921310006691.

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AbstractAccretion onto the massive black hole at the centre of a galaxy can feed energy and momentum into its surroundings via radiation, winds, and jets. Feedback due to radiation pressure can lock the mass of the black hole onto the MBH–σ relation, and shape the final stellar bulge of the galaxy. Feedback due to the kinetic power of jets can prevent massive galaxies greatly increasing their stellar mass by heating gas, which would otherwise cool radiatively. The mechanisms involved in cosmic feedback are discussed and illustrated with observations.

20

Grudić, Michael Y., J. M. Diederik Kruijssen, Claude-André Faucher-Giguère, Philip F. Hopkins, Xiangcheng Ma, Eliot Quataert e Michael Boylan-Kolchin. "A model for the formation of stellar associations and clusters from giant molecular clouds". Monthly Notices of the Royal Astronomical Society 506, n. 3 (5 luglio 2021): 3239–58. http://dx.doi.org/10.1093/mnras/stab1894.

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ABSTRACT We present a large suite of magnetohydrodynamic simulations of turbulent, star-forming giant molecular clouds (GMCs) with stellar feedback, extending previous work by simulating 10 different random realizations for each point in the parameter space of cloud mass and size. It is found that once the clouds disperse due to stellar feedback, both self-gravitating star clusters and unbound stars generally remain, which arise from the same underlying continuum of substructured stellar density, i.e. the hierarchical cluster formation scenario. The fraction of stars that are born within gravitationally bound star clusters is related to the overall cloud star formation efficiency set by stellar feedback, but has significant scatter due to stochastic variations in the small-scale details of the star-forming gas flow. We use our numerical results to calibrate a model for mapping the bulk properties (mass, size, and metallicity) of self-gravitating GMCs on to the star cluster populations they form, expressed statistically in terms of cloud-level distributions. Synthesizing cluster catalogues from an observed GMC catalogue in M83, we find that this model predicts initial star cluster masses and sizes that are in good agreement with observations, using only standard IMF and stellar evolution models as inputs for feedback. Within our model, the ratio of the strength of gravity to stellar feedback is the key parameter setting the masses of star clusters, and of the various feedback channels direct stellar radiation (photon momentum and photoionization) is the most important on GMC scales.

21

Swartz, W. H., R. S. Stolarski, L. D. Oman, E. L. Fleming e C. H. Jackman. "Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model". Atmospheric Chemistry and Physics 12, n. 13 (12 luglio 2012): 5937–48. http://dx.doi.org/10.5194/acp-12-5937-2012.

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Abstract. The 11-yr solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOSCCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3–6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 – 3 times larger than the simulation using the NRL SSI. The GEOSCCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. This is important in that it means that chemistry-transport models should simulate the solar cycle in ozone well, while general circulation models without coupled chemistry will underestimate the temperature response to the solar cycle significantly in the middle atmosphere. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) and Spectral Irradiance Monitor (SIM) on SORCE, respectively. A higher wavelength-resolution analysis of the spectral response could allow for a better prediction of the atmospheric response to arbitrary SSI variations.

22

Murray, Norman. "Feedback and Outflows". Proceedings of the International Astronomical Union 8, S292 (agosto 2012): 343–50. http://dx.doi.org/10.1017/s1743921313001671.

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AbstractThe low stellar and gas mass fractions, low galaxy-wide star formation rates (relative to galactic dynamical times) and observations of rapid outflows from galaxies, all suggest that stars and active galactic nuclei violently alter the state of the interstellar and even inter-halo gas in galaxies. I argue that the low galaxy wide star formation rates are not the result of turbulent suppression of star formation on small scale, but rather the result of a balance between dynamical pressure and the force (or rate of momentum deposition) provided by stellar feedback, either in the form of radiation pressure or by supernovae. Galaxy scale winds can also be driven by feedback, either from stars or active galactic nuclei, although the exact mechanisms involved are still not well determined.

23

Zaragoza-Cardiel, Javier, Jacopo Fritz, Itziar Aretxaga, Yalia D. Mayya, Daniel Rosa-González, John E. Beckman, Gustavo Bruzual e Stephane Charlot. "A quantitative demonstration that stellar feedback locally regulates galaxy growth". Monthly Notices of the Royal Astronomical Society 499, n. 1 (23 settembre 2020): 1172–87. http://dx.doi.org/10.1093/mnras/staa2906.

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ABSTRACT We have applied stellar population synthesis to 500-pc-sized regions in a sample of 102 galaxy discs observed with the MUSE spectrograph. We derived the star formation history and analyse specifically the ‘recent’ ($20\,\rm {Myr}$) and ‘past’ ($570\,\rm {Myr}$) age bins. Using a star formation self-regulator model, we can derive local mass-loading factors, η for specific regions, and find that this factor depends on the local stellar mass surface density, Σ*, in agreement with the predictions form hydrodynamical simulations including supernova feedback. We integrate the local η–Σ* relation using the stellar mass surface density profiles from the Spitzer Survey of Stellar Structure in Galaxies (S4G) to derive global mass-loading factors, ηG, as a function of stellar mass, M*. The ηG–M* relation found is in very good agreement with hydrodynamical cosmological zoom-in galaxy simulations. The method developed here offers a powerful way of testing different implementations of stellar feedback, to check on how realistic are their predictions.

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Fush, S. Trevor, Brian W. O’Shea, Devin W. Silvia, Britton D. Smith e John H. Wise. "Analyzing Star Formation Feedback Mechanisms in Cosmological Simulations". Research Notes of the AAS 6, n. 2 (25 febbraio 2022): 38. http://dx.doi.org/10.3847/2515-5172/ac5821.

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Abstract This study analyzes 18 simulated galaxies run using three prescriptions for stellar feedback, including thermal, kinetic, and interstellar medium pre-processing feedback mechanisms. Each simulation set models one of these mechanisms with 6 distinct galaxies, with varying M vir at z = 0. The morphological and thermodynamic quantities and distributions, as well as star formation histories, are compared to understand the impact of each stellar feedback mechanism. We find that the prescription for stellar feedback makes a significant impact on the behavior of galaxies, and observe systematic trends within each simulation and across mass ranges. Specifically, kinetic feedback results in no formation of a disk structure and delayed star formation, and pre-processing of the interstellar medium results in delayed star formation as compared to the thermal feedback mechanisms.

25

Keller, B. W. "Where Did the Outskirts Go? Outer Stellar Halos as a Sensitive Probe of Supernova Feedback". Astrophysical Journal 939, n. 1 (26 ottobre 2022): 4. http://dx.doi.org/10.3847/1538-4357/ac92fe.

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Abstract A recent comparison by Merritt of simulated and observed Milky Way–mass galaxies has identified a significant tension between the outskirts (r > 20 kpc) of the stellar halos in simulated and observed galaxies. Using observations from the Dragonfly telescope and simulated galaxies from the Illustris-TNG100 project, Merritt found that the outskirts of stellar halos in simulated galaxies have surface densities 1–2 dex higher than those of observed galaxies. In this paper, we compare two suites of 15 simulated Milky Way–like galaxies, each drawn from the same initial conditions, simulated with the same hydrodynamical code, but with two different models for feedback from supernovae. We find that the McMaster Unbiased Galaxy Simulations (MUGS), which use an older “delayed-cooling” model for feedback, also produce too much stellar mass in the outskirts of the halo, with median surface densities well above observational constraints. The MUGS2 simulations, which instead use a new, physically motivated “superbubble” model for stellar feedback, have 1–2 dex lower outer stellar halo masses and surface densities. The MUGS2 simulations generally match both the median surface density profile as well as the scatter in stellar halo surface density profiles seen in observed stellar halos. We conclude that there is no “missing outskirts” problem in cosmological simulations, provided that supernova feedback is modeled in a way that allows it to efficiently regulate star formation in the low-mass progenitor environments of stellar halo outskirts.

26

Bally, John. "Dynamical processes in star forming regions: feedback and turbulence generation". Proceedings of the International Astronomical Union 2, S237 (agosto 2006): 165–71. http://dx.doi.org/10.1017/s1743921307001408.

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AbstractYoung stellar objects (YSOs) inject large amounts of momentum and kinetic energy into their surroundings. Feedback from low mass YSOs is dominated by their outflows. However, as stellar mass increases, UV photo-heating and ionization play increasingly important roles. Massive stars produce powerful stellar winds and explode as supernovae within 3 – 40 Myr after birth. While low-mass protostellar feedback can drive turbulence in cloud cores and even disrupt the star forming environment, feedback from massive stars plays important roles in the generation of cloud structure and motions in the entire ISM.

27

Grudić, Michael Y., Philip F. Hopkins, Eliot Quataert e Norman Murray. "The maximum stellar surface density due to the failure of stellar feedback". Monthly Notices of the Royal Astronomical Society 483, n. 4 (22 dicembre 2018): 5548–53. http://dx.doi.org/10.1093/mnras/sty3386.

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28

Salcido, Jaime, Richard G. Bower e Tom Theuns. "How feedback shapes galaxies: an analytic model". Monthly Notices of the Royal Astronomical Society 491, n. 4 (22 novembre 2019): 5083–100. http://dx.doi.org/10.1093/mnras/stz3156.

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ABSTRACT We introduce a simple analytic model of galaxy formation that links the growth of dark matter haloes in a cosmological background to the build-up of stellar mass within them. The model aims to identify the physical processes that drive the galaxy-halo co-evolution through cosmic time. The model restricts the role of baryonic astrophysics to setting the relation between galaxies and their haloes. Using this approach, galaxy properties can be directly predicted from the growth of their host dark matter haloes. We explore models in which the effective star formation efficiency within haloes is a function of mass (or virial temperature) and independent of time. Despite its simplicity, the model reproduces self-consistently the shape and evolution of the cosmic star formation rate density, the specific star formation rate of galaxies, and the galaxy stellar mass function, both at the present time and at high redshifts. By systematically varying the effective star formation efficiency in the model, we explore the emergence of the characteristic shape of the galaxy stellar mass function. The origin of the observed double Schechter function at low redshifts is naturally explained by two efficiency regimes in the stellar to halo mass relation, namely, a stellar feedback regulated stage, and a supermassive black hole regulated stage. By providing a set of analytic differential equations, the model can be easily extended and inverted, allowing the roles and impact of astrophysics and cosmology to be explored and understood.

29

Ciotti, Luca. "AGN feedback in numerical simulations". Proceedings of the International Astronomical Union 5, H15 (novembre 2009): 293. http://dx.doi.org/10.1017/s1743921310009348.

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AbstractThe passively evolving stellar population in elliptical galaxies (Es) provides a continuous source of fuel for accretion on the central supermassive black hole (SMBH), which is 1) extended over the entire galaxy life (but declining with cosmic time), 2) linearly proportional to the stellar mass of the host spheroid, 3) summing up to a total gas mass that is > 100 times larger than the currently observed SMBH masses, 4) available independently of merging events. The main results of numerical simulations of Es with central SMBH, in which a physically based implementation of radiative and mechanical feedback effects is considered, are presented.

30

Garratt-Smithson, Lilian, Graham A. Wynn, Chris Power e C. J. Nixon. "Galactic chimney sweeping: the effect of ‘gradual’ stellar feedback mechanisms on the evolution of dwarf galaxies". Monthly Notices of the Royal Astronomical Society 489, n. 3 (2 settembre 2019): 4278–99. http://dx.doi.org/10.1093/mnras/stz2406.

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ABSTRACT We investigate the impact of time-resolved ‘gradual’ stellar feedback processes in high redshift dwarf spheroidal galaxies. Here ‘gradual’ feedback refers to individual stellar feedback events which deposit energy over a period of time. We conduct high-resolution hydrodynamical simulations of dwarf spheroidal galaxies with halo masses of 107–108 M⊙, based on z = 6 progenitors of the Milky Way’s dwarf spheroidal galaxies. We also include a novel feedback prescription for individual massive stars, which includes stellar winds and an HMXB (high mass X-ray binary) phase, on top of supernovae. We find the mass of gas unbound across a 1 Gyr starburst is uniformly lowered if gradual feedback mechanisms are included across the range of metallicities, halo concentration parameters, and galaxy masses studied here. Furthermore, we find including gradual feedback in the smallest galaxies delays the unbinding of the majority of the gas and facilitates the production of ‘chimneys’ in the dense shell surrounding the feedback generated hot, pressurized ‘superbubble’. These ‘chimneys’ vent hot gas from the galaxy interior, lowering the temperature of the central 10 kpc of the gaseous halo. Additionally, we find radiative cooling has little effect on the energetics of simulations that include a short, violent starburst compared with those that have a longer, less concentrated starburst. Finally, we investigate the relative impact of HMXB feedback and stellar winds on our results, finding the ubiquity of stellar winds throughout each starburst makes them a defining factor in the final state of the interstellar medium.

31

Mathew, Sajay Sunny, e Christoph Federrath. "Implementation of stellar heating feedback in simulations of star cluster formation: effects on the initial mass function". Monthly Notices of the Royal Astronomical Society 496, n. 4 (6 luglio 2020): 5201–10. http://dx.doi.org/10.1093/mnras/staa1931.

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ABSTRACT Explaining the initial mass function (IMF) of stars is a long-standing problem in astrophysics. The number of complex mechanisms involved in the process of star cluster formation, such as turbulence, magnetic fields, and stellar feedback, make understanding and modelling the IMF a challenging task. In this paper, we aim to assert the importance of stellar heating feedback in the star cluster formation process and its effect on the shape of the IMF. We use an analytical sub-grid model to implement the radiative feedback in fully three-dimensional magnetohydrodynamical (MHD) simulations of star cluster formation, with the ultimate objective of obtaining numerical convergence on the IMF. We compare a set of MHD adaptive mesh refinement simulations with three different implementations of the heating of the gas: (1) a polytropic equation of state, (2) a spherically symmetric stellar heating feedback, and (3) our newly developed polar heating model that takes into account the geometry of the accretion disc and the resulting shielding of stellar radiation by dust. For each of the three heating models, we analyse the distribution of stellar masses formed in 10 molecular cloud simulations with different realizations of the turbulence to obtain a statistically representative IMF. We conclude that stellar heating feedback has a profound influence on the number of stars formed and plays a crucial role in controlling the IMF. We find that the simulations with the polar heating model achieve the best convergence on the observed IMF.

32

Zenocratti, L. J., M. E. De Rossi, M. A. Lara-López e T. Theuns. "Correlations between mass, stellar kinematics, and gas metallicity in eagle galaxies". Monthly Notices of the Royal Astronomical Society: Letters 496, n. 1 (15 maggio 2020): L33—L37. http://dx.doi.org/10.1093/mnrasl/slaa085.

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ABSTRACT The metallicity of star-forming gas in galaxies from the eagle (Evolution and Assembly of GaLaxies and their Environments) simulations increases with stellar mass. Here, we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift z = 0, galaxies with more rotational support have lower metallicities on average when the stellar mass is below M⋆ ≈ 1010 M⊙. This trend inverts at higher values of M⋆, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mass but more pronounced at high stellar mass. We argue that the secondary dependence of metallicity on stellar kinematics is another manifestation of the observed anticorrelation between metallicity and star formation rate at a given stellar mass. At low masses, such trends seem to be driven by the different star formation histories of galaxies and stellar feedback. At high masses, feedback from active galactic nuclei and galaxy mergers plays a dominant role.

33

Grudić, Michael Y., Michael Boylan-Kolchin, Claude-André Faucher-Giguère e Philip F. Hopkins. "The universal acceleration scale from stellar feedback". Monthly Notices of the Royal Astronomical Society: Letters 496, n. 1 (1 giugno 2020): L127—L132. http://dx.doi.org/10.1093/mnrasl/slaa103.

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ABSTRACT It has been established for decades that rotation curves deviate from the Newtonian gravity expectation given baryons alone below a characteristic acceleration scale $g_{\dagger }\sim 10^{-8}\, \rm {cm\, s^{-2}}$, a scale promoted to a new fundamental constant in MOND. In recent years, theoretical and observational studies have shown that the star formation efficiency (SFE) of dense gas scales with surface density, SFE ∼ Σ/Σcrit with $\Sigma _{\rm crit} \sim \langle \dot{p}/m_{\ast }\rangle /(\pi \, G)\sim 1000\, \rm {M_{\odot }\, pc^{-2}}$ (where $\langle \dot{p}/m_{\ast }\rangle$ is the momentum flux output by stellar feedback per unit stellar mass in a young stellar population). We argue that the SFE, more generally, should scale with the local gravitational acceleration, i.e. that SFE ${\sim}g_{\rm tot}/g_{\rm crit}\equiv (G\, M_{\rm tot}/R^{2}) / \langle \dot{p}/m_{\ast }\rangle$, where Mtot is the total gravitating mass and $g_{\rm crit}=\langle \dot{p}/m_{\ast }\rangle = \pi \, G\, \Sigma _{\rm crit} \approx 10^{-8}\, \rm {cm\, s^{-2}} \approx \mathit{ g}_{\dagger }$. Hence, the observed g† may correspond to the characteristic acceleration scale above which stellar feedback cannot prevent efficient star formation, and baryons will eventually come to dominate. We further show how this may give rise to the observed acceleration scaling $g_{\rm obs}\sim (g_{\rm baryon}\, g_{\dagger })^{1/2}$ (where gbaryon is the acceleration due to baryons alone) and flat rotation curves. The derived characteristic acceleration g† can be expressed in terms of fundamental constants (gravitational constant, proton mass, and Thomson cross-section): $g_{\dagger }\sim 0.1\, G\, m_{\mathrm{ p}}/\sigma _{\rm T}$.

34

Sales, Laura V., Federico Marinacci, Volker Springel e Margarita Petkova. "Stellar feedback by radiation pressure and photoionization". Monthly Notices of the Royal Astronomical Society 439, n. 3 (20 febbraio 2014): 2990–3006. http://dx.doi.org/10.1093/mnras/stu155.

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35

Kobayashi, Chiaki, e Philip Taylor. "Metallicities in cosmological simulations with AGN feedback". Proceedings of the International Astronomical Union 11, S319 (agosto 2015): 60. http://dx.doi.org/10.1017/s1743921315010352.

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AbstractIn our cosmological, chemodynamical simulations, (i) the black hole mass–velocity dispersion relation does not evolve, and black holes actually grow along the relation. (ii) the stellar mass–metallicity relation does not change its shape, while the gas-phase relation has a steeper slope at higher redshifts. (iii) While stellar metallicity gradients are made shallower by galaxy mergers, gas-phase gradients are affected more strongly by AGN feedback.

36

Martin, Crystal L. "Starburst Feedback in Local, Massive Galaxies". Proceedings of the International Astronomical Union 2, S235 (agosto 2006): 280–83. http://dx.doi.org/10.1017/s1743921306006600.

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Major mergers of gas-rich galaxies, each comparable in mass to the Milky Way, are rare at the present epoch. These events were readily identifed, however, two decades ago in far-infrared sky surveys (Soifer et al. 1986, 1987). Removal of the dust enshrouding these starbursts was almost immediately proposed as an evolutionary path to quasar formation (Sanders 1988). Recent measurements of the stellar velocity dispersion, rotation speed, and stellar surface brightness profile of these mergers suggest ULIRGs are indeed progenitors of field elliptical galaxies (Genzel et al. 2001; Tacconi et al. 2002).

37

Pittard, Julian M., e Hazel Rogers. "Stellar wind and supernova feedback from massive stars". Proceedings of the International Astronomical Union 10, H16 (agosto 2012): 586. http://dx.doi.org/10.1017/s1743921314012289.

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AbstractWe have constructed three-dimensional hydrodynamical models to simulate the impact of massive star feedback, via winds and SNe, on inhomogeneous molecular material left over from the formation of a massive stellar cluster. We are studying the timescales for the molecular material to be removed from the environment of a massive stellar cluster and the mass and energy fluxes into the wider environment.

38

Wu, Xiaohan, Rahul Kannan, Federico Marinacci, Mark Vogelsberger e Lars Hernquist. "Simulating the effect of photoheating feedback during reionization". Monthly Notices of the Royal Astronomical Society 488, n. 1 (21 giugno 2019): 419–37. http://dx.doi.org/10.1093/mnras/stz1726.

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Abstract We present self-consistent radiation hydrodynamic simulations of hydrogen reionization performed with arepo-rt complemented by a state-of-the-art galaxy formation model. We examine how photoheating feedback, due to reionization, shapes the galaxies properties. Our fiducial model completes reionization by z ≈ 6 and matches observations of the Ly α forest, the cosmic microwave background electron scattering optical depth, the high-redshift ultraviolet (UV) luminosity function, and stellar mass function. Contrary to previous works, photoheating suppresses star formation rates by more than $50{{\ \rm per\ cent}}$ only in haloes less massive than ∼108.4 M⊙ (∼108.8 M⊙) at z = 6 (z = 5), suggesting inefficient photoheating feedback from photons within galaxies. The use of a uniform UV background that heats up the gas at z ≈ 10.7 generates an earlier onset of suppression of star formation compared to our fiducial model. This discrepancy can be mitigated by adopting a UV background model with a more realistic reionization history. In the absence of stellar feedback, photoheating alone is only able to quench haloes less massive than ∼109 M⊙ at z ≳ 5, implying that photoheating feedback is sub-dominant in regulating star formation. In addition, stellar feedback, implemented as a non-local galactic wind scheme in the simulations, weakens the strength of photoheating feedback by reducing the amount of stellar sources. Most importantly, photoheating does not leave observable imprints in the UV luminosity function, stellar mass function, or the cosmic star formation rate density. The feasibility of using these observables to detect imprints of reionization therefore requires further investigation.

39

Zhang 张, Zhijie 志杰, Xiaoxia 小霞 Zhang 张, Hui 辉. Li 李, Taotao 陶陶 Fang 方, Qingzheng 清正 Yu 余, Yang 阳. Luo 罗, Federico Marinacci, Laura V. Sales, Paul Torrey e Mark Vogelsberger. "Low- and High-velocity O vi in Milky Way-like Galaxies: The Role of Stellar Feedback". Astrophysical Journal 962, n. 1 (1 febbraio 2024): 15. http://dx.doi.org/10.3847/1538-4357/ad10a4.

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Abstract Milky Way-type galaxies are surrounded by a warm-hot gaseous halo containing a considerable amount of baryons and metals. The kinematics and spatial distribution of highly ionized ion species such as O vi can be significantly affected by supernova (SN) explosions and early (pre-SN) stellar feedback (e.g., stellar winds, radiation pressure). Here we investigate effects of stellar feedback on O vi absorptions in Milky Way−like galaxies by analyzing the suites of high-resolution hydrodynamical simulations under the framework of SMUGGLE, a physically motivated subgrid interstellar medium and stellar feedback model for the moving-mesh code Arepo. We find that the fiducial run with the full suite of stellar feedback and moderate star formation activities can reasonably reproduce Galactic O vi absorptions observed by space telescopes such as the Far-Ultraviolet Spectroscopic Explorer, including the scale height of low-velocity (∣v LSR∣ < 100 km s−1) O vi, the column density–line width relation for high-velocity (100 km s−1 ≤ ∣v LSR∣ < 400 km s−1) O vi, and the cumulative O vi column densities. In contrast, model variations with more intense star formation activities deviate from observations further. Additionally, we find that the run considering only SN feedback is in broad agreement with the observations, whereas in runs without SN feedback this agreement is absent, which indicates a dominant role of SN feedback in heating and accelerating interstellar O vi. This is consistent with the current picture that interstellar O vi is predominantly produced by collisional ionization where mechanical feedback can play a central role. In contrast, photoionization is negligible for O vi production owing to the lack of high-energy (≳114 eV) photons required.

40

Chen, Ke-Jung, Myoungwon Jeon, Thomas Greif, Volker Bromm e Alexander Heger. "Impact of the First Stars to the First Galaxy Formation". Proceedings of the International Astronomical Union 8, S295 (agosto 2012): 21. http://dx.doi.org/10.1017/s1743921313004171.

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AbstractWe present the results from our cosmological simulations of the first stages of galaxy formation. We use Gadget-2 (Springel 2005), modified to include detailed cooling, chemistry, and radiative transfer of primordial gas to study the impact of the first stars on galaxy formation. In contrast to previous work, we apply a realistic treatment of stellar feedback by using updated stellar models for the first stars. In this proceeding, we briefly summarize how stellar feedback from the first stars affects the primordial IGM inside the first galaxies.

41

Li, Hui, Mark Vogelsberger, Federico Marinacci e Oleg Y. Gnedin. "Disruption of giant molecular clouds and formation of bound star clusters under the influence of momentum stellar feedback". Monthly Notices of the Royal Astronomical Society 487, n. 1 (17 maggio 2019): 364–80. http://dx.doi.org/10.1093/mnras/stz1271.

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Abstract Energetic feedback from star clusters plays a pivotal role in shaping the dynamical evolution of giant molecular clouds (GMCs). To study the effects of stellar feedback on the star formation efficiency of the clouds and the dynamical response of embedded star clusters, we perform a suite of isolated GMC simulations with star formation and momentum feedback subgrid models using the moving-mesh hydrodynamics code Arepo. The properties of our simulated GMCs span a wide range of initial mass, radius, and velocity configurations. We find that the ratio of the final stellar mass to the total cloud mass, ϵint, scales strongly with the initial cloud surface density and momentum feedback strength. This correlation is explained by an analytic model that considers force balancing between gravity and momentum feedback. For all simulated GMCs, the stellar density profiles are systematically steeper than that of the gas at the epochs of the peaks of star formation, suggesting a centrally concentrated stellar distribution. We also find that star clusters are always in a sub-virial state with a virial parameter ∼0.6 prior to gas expulsion. Both the sub-virial dynamical state and steeper stellar density profiles prevent clusters from dispersal during the gas removal phase of their evolution. The final cluster bound fraction is a continuously increasing function of ϵint. GMCs with star formation efficiency smaller than 0.5 are still able to form clusters with large bound fractions.

42

Rathjen, Tim-Eric, Thorsten Naab, Philipp Girichidis, Stefanie Walch, Richard Wünsch, Frantis̆ek Dinnbier, Daniel Seifried, Ralf S. Klessen e Simon C. O. Glover. "SILCC VI – Multiphase ISM structure, stellar clustering, and outflows with supernovae, stellar winds, ionizing radiation, and cosmic rays". Monthly Notices of the Royal Astronomical Society 504, n. 1 (27 marzo 2021): 1039–61. http://dx.doi.org/10.1093/mnras/stab900.

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ABSTRACT We present simulations of the multiphase interstellar medium (ISM) at solar neighbourhood conditions including thermal and non-thermal ISM processes, star cluster formation, and feedback from massive stars: stellar winds, hydrogen ionizing radiation computed with the novel treeray radiative transfer method, supernovae (SN), and the injection of cosmic rays (CR). N-body dynamics is computed with a 4th-order Hermite integrator. We systematically investigate the impact of stellar feedback on the self-gravitating ISM with magnetic fields, CR advection and diffusion, and non-equilibrium chemical evolution. SN-only feedback results in strongly clustered star formation with very high star cluster masses, a bi-modal distribution of the ambient SN densities, and low volume-filling factors (VFF) of warm gas, typically inconsistent with local conditions. Early radiative feedback prevents an initial starburst, reduces star cluster masses and outflow rates. Furthermore, star formation rate surface densities of $\Sigma _{\dot{M}_\star } = 1.4-5.9 \times 10^{-3}$$\mathrm{M}_\odot \, \mathrm{yr}^{-1}\, \mathrm{kpc}^{-2}$, VFFwarm = 60–80 per cent as well as thermal, kinetic, magnetic, and cosmic ray energy densities of the model including all feedback mechanisms agree well with observational constraints. On the short, 100 Myr, time-scales investigated here, CRs only have a moderate impact on star formation and the multiphase gas structure and result in cooler outflows, if present. Our models indicate that at low gas surface densities SN-only feedback only captures some characteristics of the star-forming ISM and outflows/inflows relevant for regulating star formation. Instead, star formation is regulated on star cluster scales by radiation and winds from massive stars in clusters, whose peak masses agree with solar neighbourhood estimates.

43

Iani, E., A. Zanella, J. Vernet, J. Richard, M. Gronke, C. M. Harrison, F. Arrigoni-Battaia et al. "Stellar feedback in a clumpy galaxy at z ∼ 3.4". Monthly Notices of the Royal Astronomical Society 507, n. 3 (23 agosto 2021): 3830–48. http://dx.doi.org/10.1093/mnras/stab2376.

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ABSTRACT Giant star-forming regions (clumps) are widespread features of galaxies at z ≈ 1−4. Theory predicts that they can play a crucial role in galaxy evolution, if they survive to stellar feedback for >50 Myr. Numerical simulations show that clumps’ survival depends on the stellar feedback recipes that are adopted. Up to date, observational constraints on both clumps’ outflows strength and gas removal time-scale are still uncertain. In this context, we study a line-emitting galaxy at redshift z ≃ 3.4 lensed by the foreground galaxy cluster Abell 2895. Four compact clumps with sizes ≲280 pc and representative of the low-mass end of clumps’ mass distribution (stellar masses ≲2 × 108 M⊙) dominate the galaxy morphology. The clumps are likely forming stars in a starbursting mode and have a young stellar population (∼10 Myr). The properties of the Lyman-α (Lyα) emission and nebular far-ultraviolet absorption lines indicate the presence of ejected material with global outflowing velocities of ∼200–300 km s−1. Assuming that the detected outflows are the consequence of star formation feedback, we infer an average mass loading factor (η) for the clumps of ∼1.8–2.4 consistent with results obtained from hydrodynamical simulations of clumpy galaxies that assume relatively strong stellar feedback. Assuming no gas inflows (semiclosed box model), the estimates of η suggest that the time-scale over which the outflows expel the molecular gas reservoir (≃7 × 108 M⊙) of the four detected low-mass clumps is ≲50 Myr.

44

Costa, Tiago, Joakim Rosdahl e Taysun Kimm. "The hidden satellites of massive galaxies and quasars at high redshift". Monthly Notices of the Royal Astronomical Society 489, n. 4 (21 settembre 2019): 5181–86. http://dx.doi.org/10.1093/mnras/stz2471.

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ABSTRACT Using cosmological, radiation-hydrodynamic simulations targeting a rare ${\approx}2 \times 10^{12} \, \rm {\rm M}_{\odot }$ halo at $z = 6$, we show that the number counts and internal properties of satellite galaxies within the massive halo are sensitively regulated by a combination of local stellar radiative feedback and strong tidal forces. Radiative feedback operates before the first supernova explosions erupt and results in less tightly bound galaxies. Satellites are therefore more vulnerable to tidal stripping when they accrete on to the main progenitor and are tidally disrupted on a significantly shorter time-scale. Consequently, the number of satellites with $M_{\rm \star } \gt 10^{7} \, \rm {\rm M}_{\odot }$ within the parent system’s virial radius drops by up to $60 \, {\rm per\, cent}$ with respect to an identical simulation performed without stellar radiative feedback. Radiative feedback also impacts the central galaxy, whose effective radius increases by a factor ≲3 due to the presence of a more extended and diffuse stellar component. We suggest that the number of satellites in the vicinity of massive high-redshift galaxies is an indication of the strength of stellar radiative feedback and can be anomalously low in the extreme cosmic environments of high-redshift quasars.

45

Davies, L. J. M., J. E. Thorne, S. Bellstedt, M. Bravo, A. S. G. Robotham, S. P. Driver, R. H. W. Cook et al. "Deep Extragalactic VIsible Legacy Survey (DEVILS): evolution of the σSFR–M⋆ relation and implications for self-regulated star formation". Monthly Notices of the Royal Astronomical Society 509, n. 3 (9 novembre 2021): 4392–410. http://dx.doi.org/10.1093/mnras/stab3145.

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ABSTRACT We present the evolution of the star formation dispersion–stellar mass relation (σSFR–M⋆) in the DEVILS D10 region using new measurements derived using the ProSpect spectral energy distribution fitting code. We find that σSFR–M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1 < z < 0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical interpretation of this relation is the combination of stochastic star formation and stellar feedback causing large scatter at low stellar masses and AGN feedback causing asymmetric scatter at high stellar masses. As such, the shape of this distribution and its evolution encodes detailed information about the astrophysical processes affecting star formation, feedback and the lifecycle of galaxies. We find that the stellar mass that the minimum σSFR occurs evolves linearly with redshift, moving to higher stellar masses with increasing lookback time and traces the turnover in the star-forming sequence. This minimum σSFR point is also found to occur at a fixed specific star formation rate (sSFR) at all epochs (sSFR ∼ 10−9.6 Gyr−1). The physical interpretation of this is that there exists a maximum sSFR at which galaxies can internally self-regulate on the tight sequence of star formation. At higher sSFRs, stochastic stellar processes begin to cause galaxies to be pushed both above and below the star-forming sequence leading to increased SFR dispersion. As the Universe evolves, a higher fraction of galaxies will drop below this sSFR threshold, causing the dispersion of the low stellar mass end of the star-forming sequence to decrease with time.

46

Kado-Fong, Erin, Robyn E. Sanderson, Jenny E. Greene, Emily C. Cunningham, Coral Wheeler, T. K. Chan, Kareem El-Badry et al. "The In Situ Origins of Dwarf Stellar Outskirts in FIRE-2". Astrophysical Journal 931, n. 2 (1 giugno 2022): 152. http://dx.doi.org/10.3847/1538-4357/ac6c88.

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Abstract Extended, old, and round stellar halos appear to be ubiquitous around high-mass dwarf galaxies (108.5 < M ⋆/M ⊙ < 109.6) in the observed universe. However, it is unlikely that these dwarfs have undergone a sufficient number of minor mergers to form stellar halos that are composed of predominantly accreted stars. Here, we demonstrate that FIRE-2 (Feedback in Realistic Environments) cosmological zoom-in simulations are capable of producing dwarf galaxies with realistic structures, including both a thick disk and round stellar halo. Crucially, these stellar halos are formed in situ, largely via the outward migration of disk stars. However, there also exists a large population of “nondisky” dwarfs in FIRE-2 that lack a well-defined disk/halo and do not resemble the observed dwarf population. These nondisky dwarfs tend to be either more gas-poor or to have burstier recent star formation histories than the disky dwarfs, suggesting that star formation feedback may be preventing disk formation. Both classes of dwarfs underscore the power of a galaxy’s intrinsic shape—which is a direct quantification of the distribution of the galaxy’s stellar content—to interrogate the feedback implementation in simulated galaxies.

47

Martizzi, Davide, Romain Teyssier e Ben Moore. "The role of Active Galactic Nuclei feedback in the formation of the brightest cluster galaxies". Proceedings of the International Astronomical Union 8, S295 (agosto 2012): 362–65. http://dx.doi.org/10.1017/s1743921313005371.

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AbstractThe formation of the brightest cluster galaxies (BCG) is a challenge for galaxy formation theory. We performed high resolution cosmological hydrodynamical simulations with the AMR code RAMSES to study the properties of the BCG which forms at the center of a Virgo–like cluster. We compare the results of 2 galaxy formation scenarios, one in which only supernovae feedback is included, and one in which also AGN feedback is considered. Properties of the simulated BCG which are comparable with those of observed massive elliptical galaxies and BCGs cannot be obtained if AGN feedback is not considered. The stellar-to-halo mass ratio in simulations without AGN feedback appears too large when compared to observations, while it is compatible the observationally determined values when AGN feedback is included. The kinematical and structural properties of the BCG are extremely different in the two models. When we do not include AGN feedback, the BCG is quickly rotating, with high Sérsic index, a clear mass excess in the center and a very large stellar mass fraction. When AGN feedback is considered, the BCG is slowly rotating, with a significantly cored surface density profile and low stellar mass fraction.

48

Parsotan, T., R. K. Cochrane, C. C. Hayward, D. Anglés-Alcázar, R. Feldmann, C. A. Faucher-Giguère, S. Wellons e P. F. Hopkins. "Realistic mock observations of the sizes and stellar mass surface densities of massive galaxies in FIRE-2 zoom-in simulations". Monthly Notices of the Royal Astronomical Society 501, n. 2 (5 dicembre 2020): 1591–602. http://dx.doi.org/10.1093/mnras/staa3765.

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ABSTRACT The galaxy size–stellar mass and central surface density–stellar mass relationships are fundamental observational constraints on galaxy formation models. However, inferring the physical size of a galaxy from observed stellar emission is non-trivial due to various observational effects, such as the mass-to-light ratio variations that can be caused by non-uniform stellar ages, metallicities, and dust attenuation. Consequently, forward-modelling light-based sizes from simulations is desirable. In this work, we use the skirt dust radiative transfer code to generate synthetic observations of massive galaxies ($M_{*}\sim 10^{11}\, \rm {M_{\odot }}$ at z = 2, hosted by haloes of mass $M_{\rm {halo}}\sim 10^{12.5}\, \rm {M_{\odot }}$) from high-resolution cosmological zoom-in simulations that form part of the Feedback In Realistic Environments project. The simulations used in this paper include explicit stellar feedback but no active galactic nucleus (AGN) feedback. From each mock observation, we infer the effective radius (Re), as well as the stellar mass surface density within this radius and within $1\, \rm {kpc}$ (Σe and Σ1, respectively). We first investigate how well the intrinsic half-mass radius and stellar mass surface density can be inferred from observables. The majority of predicted sizes and surface densities are within a factor of 2 of the intrinsic values. We then compare our predictions to the observed size–mass relationship and the Σ1−M⋆ and Σe−M⋆ relationships. At z ≳ 2, the simulated massive galaxies are in general agreement with observational scaling relations. At z ≲ 2, they evolve to become too compact but still star forming, in the stellar mass and redshift regime where many of them should be quenched. Our results suggest that some additional source of feedback, such as AGN-driven outflows, is necessary in order to decrease the central densities of the simulated massive galaxies to bring them into agreement with observations at z ≲ 2.

49

Kuiper, R., e T. Hosokawa. "First hydrodynamics simulations of radiation forces and photoionization feedback in massive star formation". Astronomy & Astrophysics 616 (agosto 2018): A101. http://dx.doi.org/10.1051/0004-6361/201832638.

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Aims. We present the first simulations of the formation and feedback of massive stars which account for radiation forces as well as photoionization feedback (along with protostellar outflows). In two different accretion scenarios modeled, we determine the relative strength of these feedback components and derive the size of the reservoir from which the forming stars gained their masses. Methods. We performed direct hydrodynamics simulations of the gravitational collapse of high-density mass reservoirs toward the formation of massive stars including self-gravity, stellar evolution, protostellar outflows, continuum radiation transport, photoionization, and the potential impact of ram pressure from large-scale gravitational infall. For direct comparison, we executed these simulations with and without the individual feedback components. Results. Protostellar outflows alone limit the stellar mass growth only in an accretion scenario with a finite mass reservoir; when including accretion and ram pressure from large scales (>0.1 pc), protostellar outflows do not limit stellar mass growth at all. Photoionization and HII regions dominate the feedback ladder only at later times, after the star has already contracted down to the zero-age main sequence, and only on large scales. Specifically, photoionization yields a broadening of the bipolar outflow cavities and a reduction of the gravitational infall momentum by about 50%, but does not limit the stellar mass accretion. On the other hand, we find radiation forces restrain the gravitational infall toward the circumstellar disk, impact the gravito-centrifugal equilibrium at the outer edge of the disk, and eventually shut down stellar accretion completely. The most massive star formed in the simulations accreted 95 M⊙ before disk destruction; this mass was drawn-in from an accretion reservoir of ≈240 M⊙ and ≈0.24 pc in radius. Conclusions. In the regime of very massive stars, the final mass of these stars is controlled by their own radiation force feedback.

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Blackman, Eric G. "Cloud fragmentation cascades and feedback: on reconciling an unfettered inertial range with a low star formation rate". Monthly Notices of the Royal Astronomical Society 493, n. 1 (4 febbraio 2020): 815–20. http://dx.doi.org/10.1093/mnras/staa326.

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Abstract (sommario):

ABSTRACT Molecular cloud complexes exhibit both (i) an unfettered Larson-type spectrum over much of their dynamic range, whilst (ii) still producing a much lower star formation rate than were this cascade to remain unfettered all the way down to star-forming scales. Here we explain the compatibility of these attributes with minimalist considerations of a mass-conserving fragmentation cascade, combined with estimates of stellar feedback. Of importance is that the amount of feedback needed to abate fragmentation and truncate the complex decreases with decreasing scale. The scale at which the feedback momentum matches the free-fall momentum marks a transition scale below most of the cascade is truncated and the molecular cloud complex dissipated. For a 106 M⊙ giant molecular cloud (GMC) complex starting with radius of ∼50 pc, the combined feedback from young stellar objects, supernovae, radiation, and stellar winds for a GMC cloud complex can truncate the cascade within an outer free-fall time but only after the cascade reaches parsec scales.

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