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Zeitschriftenartikel zum Thema „AGN activity“

Autor: Grafiati

Veröffentlicht am 26. Juni 2021

Zuletzt aktualisiert am 17. Februar 2022

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1

Umemura, Masayuki, Jun Fukue und Shin Mineshige. „AGN activity triggered by circumnuclear starbursts“. Advances in Space Research 23, Nr. 5-6 (Januar 1999): 1095–100. http://dx.doi.org/10.1016/s0273-1177(99)00238-0.

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2

Li, Cheng, Guinevere Kauffmann, Timothy M. Heckman, Simon D. M. White und Y. P. Jing. „Interactions, star formation and AGN activity“. Monthly Notices of the Royal Astronomical Society 385, Nr. 4 (April 2008): 1915–22. http://dx.doi.org/10.1111/j.1365-2966.2008.13023.x.

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3

Amiri, Amirnezam. „Role of environment on AGN activity“. Proceedings of the International Astronomical Union 15, S356 (Oktober 2019): 171. http://dx.doi.org/10.1017/s1743921320002835.

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AbstractMotivated by the apparently conflicting results reported in the literature on the effect of environment on nuclear activity, we have carried out a new analysis by comparing the fraction of galaxies hosting active galactic nuclei (AGNs) in the most overdense regions (rich galaxy clusters) and the most underdense ones (voids) in the local universe. Exploiting the classical BPT diagnostics, we have extracted volume limited samples of star forming and AGN galaxies. We find that, at variance with star-forming galaxies, AGN galaxies have similar distributions of specific star formation rates and of galactic ages (as indicated by the Dn4000 parameter) both in clusters and in voids. In both environments galaxies hosting AGNs are generally old, with low star formation activity. The AGN fraction increases faster with stellar mass in clusters than in voids, especially above 1010.2 M⊙. Our results indicate that, in the local universe, the nuclear activity correlates with stellar mass and galaxy morphology and is weakly, if at all, affected by the local galaxy density.

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4

Man, Zhong-yi, Ying-jie Peng, Xu Kong, Ke-xin Guo, Cheng-peng Zhang und Jing Dou. „The dependence of AGN activity on environment in SDSS“. Monthly Notices of the Royal Astronomical Society 488, Nr. 1 (20.06.2019): 89–98. http://dx.doi.org/10.1093/mnras/stz1706.

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ABSTRACT Environment is one of the key external drivers of the galaxies, while active galactic nucleus (AGN) is one of the key internal drivers. Both of them play fundamental roles in regulating the formation and evolution of galaxies. We explore the interrelationship between environment and AGN in SDSS. At a given stellar mass, the specific star formation rate distribution of the AGN host galaxies remains unchanged with overdensity, with the peak of the distribution around the Green Valley. We show that, at a given stellar mass, the AGN fraction that has been commonly used in previous studies (defined as the number of AGNs relative to all galaxies including passive and star forming ones) does decrease with increasing overdensity for satellites. This is largely due to the fact that the fraction of passive galaxies strongly depends on environment. In order to investigate the intrinsic correlation between AGN and environment, especially under the assumption that AGN feedback is responsible for star formation quenching, the AGN fraction should be defined as the number of AGNs relative to the star-forming galaxies only. With the new definition, we find little dependence of AGN fraction on overdensity, central/satellite, and group halo mass. There is only marginal evidence that AGN may prefer denser regions, which is possibly due to more frequent interaction of galaxies or higher merger rate in groups. Our results support the scenario that internal secular evolution is the predominant mechanism of triggering AGN activity, while external environment related processes only play a minor role.

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5

González Delgado, R. M., C. N. Tadhunter, E. Pérez, M. Villar-Martín, J. Holt und J. Rodríguez. „The relation between mergers and AGN activity“. Astronomische Nachrichten 327, Nr. 2-3 (März 2006): 159–66. http://dx.doi.org/10.1002/asna.200510499.

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6

De Rosa, A., S. Bianchi, T. Bogdanović, R. Decarli, J. Heidt, R. Herrero-Illana, B. Husemann et al. „Unveiling multiple AGN activity in galaxy mergers“. Astronomische Nachrichten 338, Nr. 2-3 (März 2017): 262–68. http://dx.doi.org/10.1002/asna.201713340.

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7

Noordeh, E., R. E. A. Canning, A. King, S. W. Allen, A. Mantz, R. G. Morris, S. Ehlert et al. „The environmental dependence of X-ray AGN activity at z ∼ 0.4“. Monthly Notices of the Royal Astronomical Society 498, Nr. 3 (07.09.2020): 4095–108. http://dx.doi.org/10.1093/mnras/staa2682.

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ABSTRACT We present an analysis of the X-ray active galactic nucleus (AGN) population in a sample of seven massive galaxy clusters in the redshift range 0.35 < z < 0.45. We utilize high-quality Chandra X-ray imaging to robustly identify AGN and precisely determine cluster masses and centroids. Follow-up VIsible Multi-Object Spectrograph optical spectroscopy allows us to determine which AGN are cluster members. Studying the subset of AGN with 0.5–8 keV luminosities >6.8 × 1042 erg s−1, within r ≤ 2r500 (approximately the virial radius), we find that the cluster AGN space density scales with cluster mass as $\sim M^{-2.0^{+0.8}_{-0.9}}$. This result rules out zero mass dependence of the cluster X-ray AGN space density at the 2.5σ level. We compare our cluster X-ray AGN sample to a control field with identical selection and find that the cluster AGN fraction is significantly suppressed relative to the field when considering the brightest galaxies with V < 21.5. For fainter galaxies, this difference is not present. Comparing the X-ray hardness ratios of cluster member AGN to those in the control field, we find no evidence for enhanced X-ray obscuration of cluster member AGN. Lastly, we see tentative evidence that disturbed cluster environments may contribute to enhanced AGN activity.

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8

Farrah, D., J. Afonso, A. Efstathiou, M. Rowan-Robinson, M. Fox und D. Clements. „Starburst and AGN activity in ultraluminous infrared galaxies“. Monthly Notices of the Royal Astronomical Society 343, Nr. 2 (01.08.2003): 585–607. http://dx.doi.org/10.1046/j.1365-8711.2003.06696.x.

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9

Blank, Marvin, und Wolfgang J. Duschl. „Viscous time lags between starburst and AGN activity“. Monthly Notices of the Royal Astronomical Society 462, Nr. 2 (28.07.2016): 2246–55. http://dx.doi.org/10.1093/mnras/stw1804.

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10

Foord, Adi, Elena Gallo, Edmund Hodges-Kluck, Brendan P. Miller, Vivienne F. Baldassare, Kayhan Gültekin und Oleg Y. Gnedin. „AGN Activity in Nucleated Galaxies as Measured byChandra“. Astrophysical Journal 841, Nr. 1 (23.05.2017): 51. http://dx.doi.org/10.3847/1538-4357/aa6d63.

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11

Santos, Daryl Joe D., Tomotsugu Goto, Seong Jin Kim, Ting-Wen Wang, Simon C.-C. Ho, Tetsuya Hashimoto, Ting-Chi Huang et al. „Environmental effects on AGN activity via extinction-free mid-infrared census“. Monthly Notices of the Royal Astronomical Society 507, Nr. 2 (16.08.2021): 3070–88. http://dx.doi.org/10.1093/mnras/stab2352.

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ABSTRACT How does the environment affect active galactic nucleus (AGN) activity? We investigated this question in an extinction-free way by selecting 1120 infrared (IR) galaxies in the AKARI North Ecliptic Pole Wide field at redshift z ≤ 1.2. A unique feature of the AKARI satellite is its continuous nine-band IR filter coverage, providing us with an unprecedentedly large sample of IR spectral energy distributions (SEDs) of galaxies. By taking advantage of this, for the first time, we explored the AGN activity derived from SED modelling as a function of redshift, luminosity, and environment. We quantified AGN activity in two ways: AGN contribution fraction (ratio of AGN luminosity to the total IR luminosity), and AGN number fraction (ratio of number of AGNs to the total galaxy sample). We found that galaxy environment (normalized local density) does not greatly affect either definitions of AGN activity of our IRG/LIRG samples (log LTIR ≤ 12). However, we found a different behaviour for ULIRGs (log LTIR > 12). At our highest redshift bin (0.7 ≲ z ≲ 1.2), AGN activity increases with denser environments, but at the intermediate redshift bin (0.3 ≲ z ≲ 0.7), the opposite is observed. These results may hint at a different physical mechanism for ULIRGs. The trends are not statistically significant (p ≥ 0.060 at the intermediate redshift bin, and p ≥ 0.139 at the highest redshift bin). Possible different behaviour of ULIRGs is a key direction to explore further with future space missions (e.g. JWST, Euclid, SPHEREx).

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12

Paronyan, Gurgen M., Gohar S. Harutyunyan und Areg M. Mickaelian. „Activity types for X-ray candidate AGN from SDSS“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 166–67. http://dx.doi.org/10.1017/s1743921314003664.

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AbstractThe Joint Catalogue of Hamburg ROSAT Sources (HRC/BHRC) is the result of merging of HRC and BHRC catalogs built on the basis of optical identifications of ROSAT BSC and ROSAT FSC. Altogether, 8132 sources are present. Based on this catalogue, we have compiled a sample of ROSAT AGN, including candidate ones. In this paper we classify candidate AGN (those that previously had not been spectroscopically classified) by their activity type. The sample contains 955 objects with count rate of photons CR>0.04 ct/s in the area with galactic latitudes |b|>30 and declinations δ>0, however only 217 objects have SDSS DR10 spectra. The classification led to the following results: 95 AGN, 71 absorption-line galaxies, 42 stars, and 9 unclassified objects.

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13

Sani, Eleonora. „AGN/Starburst Connection“. Acta Polytechnica CTU Proceedings 1, Nr. 1 (04.12.2014): 84–89. http://dx.doi.org/10.14311/app.2014.01.0084.

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Two main physical processes characterize the activity in the nuclear region of active galaxies: an intense star formation (starburst, SB) and an Active Galactic Nucleus (AGN). While the existence of a starburst-AGN connection is undisputed, still it is not clear which process dominates the energetic output in both local and high redshift Universe. Moreover there is no consensus on whether AGN fueling is synchronous with star formation or follows it during a post-starburst phase. Here I first review how to disentangle the relative SB-AGN contribution, then I focus on the physical and geometrical properties of the circumnuclear environment.

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14

Mickaelian, A. M., H. V. Abrahamyan, G. S. Harutyunyan und G. M. Paronyan. „Revised activity types for Markarian galaxies“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 41–42. http://dx.doi.org/10.1017/s1743921314003263.

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AbstractThe sample of Markarian galaxies consists of 1515 UV-excess galaxies containing many active galaxies, both AGN and Starburst (SB). Several catalogs of Markarian galaxies have been published; however activity types are based on old spectroscopic data. The SDSS spectroscopy and some other recent spectral observations allow classify or re-classify many of Markarian galaxies, altogether we have retrieved and studied 779 SDSS and 300 other spectra. Out of 779 SDSS spectra, we have classified 533 HII, 31 Composites, 12 LINERs, 4 S2.0, 5 S1.9, 8 S1.8, 5 NLS1.5, 11 S1.5, 8 NLS1.2, 21 S1.2, 4 NLS1, 4 S1.0, 2 QSO, 11 AGN (without an exact class), 52 Em (HII or AGN), 65 Abs, and 3 Stars. On the other hand, the galaxies are being classified depending on the fact in which wavelength range they have been observed and studied. E.g. some Sy2 type galaxies turn to be Sy1 when classified in IR. Many hidden AGN (in X-ray and IR) appear to be normal galaxies in optical range. So for better understanding, IR spectra are necessary as well.

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15

Wang, Kunjie, Yanping Wu, Hongxia Li, Mingliang Li, Deyi Zhang, Huixia Feng und Haiyan Fan. „Synthesis, characterization and antimicrobial activity of silver nanoparticles: Agn(NALC)m and Agn(GSHR)m“. RSC Advances 4, Nr. 10 (2014): 5130. http://dx.doi.org/10.1039/c3ra46568c.

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16

Schmidt, Gary D. „Ubiquitous Disks in AGN“. International Astronomical Union Colloquium 163 (1997): 152–61. http://dx.doi.org/10.1017/s0252921100042597.

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AbstractDisk-like structures have been inferred to exist in the nuclei of galaxies over the entire range in nuclear activity. These form the essence of the Unified Scheme, which has had great success in accounting for AGN of a wide variety of perceived types. Recent progress along this front is summarized, including new polarimetric results, high-angular resolution optical imaging, and interferometry at radio wavelengths.

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17

Poggianti, Bianca M., Callum Bellhouse, Tirna Deb, Andrea Franchetto, Jacopo Fritz, Koshy George, Marco Gullieuszik et al. „The role of environment on quenching, star formation and AGN activity“. Proceedings of the International Astronomical Union 15, S359 (März 2020): 108–16. http://dx.doi.org/10.1017/s1743921320002070.

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AbstractGalaxies undergoing ram pressure stripping in clusters are an excellent opportunity to study the effects of environment on both the AGN and the star formation activity. We report here on the most recent results from the GASP survey. We discuss the AGN-ram pressure stripping connection and some evidence for AGN feedback in stripped galaxies. We then focus on the star formation activity, both in the disks and the tails of these galaxies, and conclude drawing a picture of the relation between multi-phase gas and star formation.

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18

Miraghaei, H., H. G. Khosroshahi, H. R. Klöckner, T. J. Ponman, N. N. Jetha und S. Raychaudhury. „IGM Heating and AGN activity in Fossil Galaxy Groups“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 349–50. http://dx.doi.org/10.1017/s174392131400427x.

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AbstractFossil galaxy groups are energetically and morphologically ideal environments to study the intergalactic medium (IGM) heating, because their inter-galactic gas is undisturbed due to the lack of recent group scale mergers. We study the role of active galactic nuclei (AGN) in heating the IGM in a sample of five fossil galaxy groups by employing properties at 610 MHz and 1.4 GHz. We find that two of the dominant galaxies in fossil groups, ESO 3060170 and RX J1416.4+2315, are associated with the radio lobes. We evaluate the PdV work of the radio lobes and their corresponding heating power and compare to the X-ray emission loss within cooling radius. Our results show that the power due to mechanical heating is not sufficiently high to suppress the cooling.

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19

McKernan, B., K. E. S. Ford und C. S. Reynolds. „Black hole mass, host galaxy classification and AGN activity“. Monthly Notices of the Royal Astronomical Society 407, Nr. 4 (20.07.2010): 2399–410. http://dx.doi.org/10.1111/j.1365-2966.2010.17068.x.

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20

Fanidakis, N., C. M. Baugh, A. J. Benson, R. G. Bower, S. Cole, C. Done und C. S. Frenk. „Grand unification of AGN activity in the ΛCDM cosmology“. Monthly Notices of the Royal Astronomical Society 410, Nr. 1 (08.10.2010): 53–74. http://dx.doi.org/10.1111/j.1365-2966.2010.17427.x.

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21

Richards, A. M. S., J. H. Knapen, J. A. Yates, R. J. Cohen, J. L. Collett, M. M. Wright, M. D. Gray und D. Field. „OH Megamasers, Starburst and AGN Activity in Markarian 231“. Monthly Notices of the Royal Astronomical Society 364, Nr. 2 (Dezember 2005): 353–66. http://dx.doi.org/10.1111/j.1365-2966.2005.09588.x.

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22

Florez, Jonathan, Shardha Jogee, Sydney Sherman, Matthew L. Stevans, Steven L. Finkelstein, Casey Papovich, Lalitwadee Kawinwanichakij et al. „Exploring AGN and star formation activity of massive galaxies at cosmic noon“. Monthly Notices of the Royal Astronomical Society 497, Nr. 3 (29.07.2020): 3273–96. http://dx.doi.org/10.1093/mnras/staa2200.

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ABSTRACT We investigate the relation between active galactic nucleus (AGN) and star formation (SF) activity at 0.5 < z < 3 by analysing 898 galaxies with X-ray luminous AGNs (LX > 1044 erg s−1) and a large comparison sample of ∼320 000 galaxies without X-ray luminous AGNs. Our samples are selected from a large (11.8 deg2) area in Stripe 82 that has multiwavelength (X-ray to far-IR) data. The enormous comoving volume (∼0.3 Gpc3) at 0.5 < z < 3 minimizes the effects of cosmic variance and captures a large number of massive galaxies (∼30 000 galaxies with M* > 1011 M⊙) and X-ray luminous AGNs. While many galaxy studies discard AGN hosts, we fit the SED of galaxies with and without X-ray luminous AGNs with Code Investigating GALaxy Emission and include AGN emission templates. We find that without this inclusion, stellar masses and star formation rates (SFRs) in AGN host galaxies can be overestimated, on average, by factors of up to ∼5 and ∼10, respectively. The average SFR of galaxies with X-ray luminous AGNs is higher by a factor of ∼3–10 compared to galaxies without X-ray luminous AGNs at fixed stellar mass and redshift, suggesting that high SFRs and high AGN X-ray luminosities may be fuelled by common mechanisms. The vast majority ($\gt 95 {{\ \rm per\ cent}}$) of galaxies with X-ray luminous AGNs at z = 0.5−3 do not show quenched SF: this suggests that if AGN feedback quenches SF, the associated quenching process takes a significant time to act and the quenched phase sets in after the highly luminous phases of AGN activity.

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23

Zubovas, Kastytis. „AGN activity and nuclear starbursts: Sgr A* activity shapes the Central Molecular Zone“. Monthly Notices of the Royal Astronomical Society 451, Nr. 4 (29.06.2015): 3627–42. http://dx.doi.org/10.1093/mnras/stv1173.

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24

Levenson, N. A. „Compton Thick AGN“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 112–18. http://dx.doi.org/10.1017/s1743921314003512.

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AbstractCompton thick active galactic nuclei (AGN), which are obscured by column density NH > 1.5 × 104 cm−2, can be difficult to identify. They are certainly cosmically significant, both in producing the observed cosmic X-ray background, and in providing a location where black hole growth is hidden from view. Here I review some recent results from surveys that provide indications of Compton thick AGN, considering X-ray, radio, and infrared selection techniques. I also offer a caution against using mid-infrared silicate features to measure line-of-sight obscuration to active galactic nuclei. Instead, these features better indicate the geometric distribution of dust that the central engine heats. I conclude that the outstanding problem of Compton thick AGN is not the cases where the obscuration is directly associated with the environment of the active nucleus itself, even in the most obscured examples. Instead, we still risk missing the completely buried AGN, which are obscured by large amounts of gas and dust over large solid angles. The solution to finding Compton thick AGN may be to begin the search based on infrared emission and star formation, and then select for nuclear activity.

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25

Greenhill, L. J. „Masers in AGN environments“. Proceedings of the International Astronomical Union 3, S242 (März 2007): 381–90. http://dx.doi.org/10.1017/s1743921307013439.

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AbstractGalactic nuclei are well known sources of OH and H2O maser emission. It appears that intense star formation in ultra-luminous infrared galaxies drives most OH sources. In contrast, nuclear activity appears to drive most H2O sources. When H2O emission originates in accretion disk structures, constrained geometry and dynamics enable robust interpretation of spectroscopic and imaging data. The principal science includes study of AGN geometry at parsec and sub-parsec radii and measurement of geometric distances in the Hubble Flow. New high accuracy estimates of the “Hubble constant, H○” obtained from maser distances may enable new substantively improved constraints on fundamental cosmological parameters (e.g., dark energy).

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26

Filho, Mercedes E., Jarle Brinchmann, Catarina Lobo und Sonia Antón. „Optically faint radio sources: reborn AGN?“ Proceedings of the International Astronomical Union 7, S284 (September 2011): 231–33. http://dx.doi.org/10.1017/s174392131200912x.

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AbstractWe have discovered eight relatively strong radio sources that have no optical counterparts. A NIR follow-up has detected faint (17–20 mag) host galaxies in all targets. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with moderate to high redshift (z < 4) GHz-peaked spectrum sources. Our results suggest that these are galaxies whose black hole has been recently re-ignited into activity but that retain large-scale radio structures, signatures of previous AGN activity.

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27

Pović, Mirjana. „Development in astronomy in Ethiopia and East-Africa through nuclear activity in galaxies“. Proceedings of the International Astronomical Union 15, S356 (Oktober 2019): 3–8. http://dx.doi.org/10.1017/s174392132000246x.

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AbstractIn this paper we summarise the research that is currently going on in Ethiopia and East-Africa in extragalactic astronomy and physics of active galaxies and active galactic nuclei (AGN). The study is focused on some of the still open questions such as: what are the stellar ages and populations of ultra hard X-ray detected AGN and connection between AGN and their host galaxies?, what are the properties of AGN in galaxy clusters and the role that environment has in triggering nuclear activity?, what are the morphological properties of AGN and how precisely we can deal with morphological classification of active galaxies?, what are the properties of galaxies in the green valley and the role of AGN in galaxy evolution?, and what are the properties of radio-loud and radio-quiet quasars (QSO) and dichotomy between the two?. Each of these questions has been developed under one specific project that will be briefly introduced. These projects involve 6 PhD and 3 MSc students and collaborations between Ethiopia, Rwanda, South Africa, Uganda, Tanzania, Spain, Italy, and Chile. With all projects we aim: first, to contribute to our general knowledge about AGN, and second, to contribute to the development in astronomy and science in Ethiopia and East-Africa.

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Stemo, Aaron, Julia M. Comerford, R. Scott Barrows, Daniel Stern, Roberto J. Assef und Roger L. Griffith. „A Catalog of AGN Host Galaxies Observed with HST/ACS: Correlations between Star Formation and AGN Activity“. Astrophysical Journal 888, Nr. 2 (10.01.2020): 78. http://dx.doi.org/10.3847/1538-4357/ab5f66.

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29

Pimbblet, K. A., S. S. Shabala, C. P. Haines, A. Fraser-McKelvie und D. J. E. Floyd. „The drivers of AGN activity in galaxy clusters: AGN fraction as a function of mass and environment“. Monthly Notices of the Royal Astronomical Society 429, Nr. 2 (20.12.2012): 1827–39. http://dx.doi.org/10.1093/mnras/sts470.

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30

Lee, Hyo Jeong, Hyo Jung Lee, Eun Ok Lee, Jae Ho Lee, Kuen Sung Lee, Kwan Hyun Kim, Sung-Hoon Kim und Junxuan Lü. „In vivo Anti-Cancer Activity of Korean Angelica Gigas and its Major Pyranocoumarin Decursin“. American Journal of Chinese Medicine 37, Nr. 01 (Januar 2009): 127–42. http://dx.doi.org/10.1142/s0192415x09006722.

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We have reported that a 10-herbal traditional formula containing Korean Angelica gigas Nakai (AGN) exerts potent anti-cancer efficacy and identified decursin and decursinol angelate (DA) from AGN as novel anti-androgens. Here, we determined whether AGN would exert in vivo anti-cancer activity and whether decursin or DA could account for its efficacy. The AGN ethanol extract was tested against the growth of mouse Lewis lung cancer (LLC) allograft in syngenic mice or human PC-3 and DU145 prostate cancer xenograft in immunodeficient mice. The pharmacokinetics of decursin and DA were determined. The AGN extract significantly inhibited LLC allograft growth (30 mg/kg) and PC-3 and DU145 xenograft growth (100 mg/kg) without affecting the body weight of the host mice. Biomarker analyses revealed decreased cell proliferation (Ki67, PCNA), decreased angiogenesis (VEGF, microvessel density) and increased apoptosis (TUNEL, cPARP) in treated tumors. Decursin and DA injected intraperitoneally were rapidly hydrolyzed to decursinol. Decursinol and decursin at 50 mg/kg inhibited LLC allograft growth to the same extent, comparable to 30 mg AGN/kg. Therefore the AGN extract possessed significant in vivo anti-cancer activity, but decursin and DA only contributed moderately to that activity, most likely through decursinol.

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Puccetti, S., F. Fiore, A. Bongiorno, K. Boutsia, R. Fassbender und M. Verdugo. „Triggering nuclear and galaxy activity in the Bullet cluster“. Astronomy & Astrophysics 634 (Februar 2020): A137. http://dx.doi.org/10.1051/0004-6361/201833601.

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The analysis of a cluster environment is a valuable instrument to investigate the origin of gas fuelling and trigger mechanisms in active galactic nuclei (AGN) and star-forming galaxies. To this purpose, we present a detailed analysis of the point-like X-ray sources in the Bullet cluster field. Based on ∼600 ks Chandra observations, we produced a catalogue of 381 X-ray point sources up to a distance of ∼1.5 virial radius and with flux limits ∼1 × 10−16 and ∼8 × 10−16 erg cm−2 s−1 in the 0.5–2 keV and 2–10 keV bands, respectively. We find a strong (up to a factor 1.5–2) and significant (≥4σ) over-density in the full region studied 0.3R200 < R < 1.5R200. We identified optical (R band) and infrared (Spitzer IRAC) counterparts for ∼84% and ∼48% of the X-ray sources, respectively. We obtained new spectroscopic redshifts for 106 X-ray sources and collected from the literature additional 13 spectroscopic and 8 photometric redshifts of X-ray sources. Twenty-nine X-ray sources turned out to be cluster members. Spectroscopic and photometric redshifts of optical and infrared sources were also collected, and these sources were used as ancillary samples. We used these multi-wavelength data to characterise the nature of the Bullet cluster X-ray point sources. We find that the over-density in the region 0.3R200 < R < R200 is likely due to X-ray AGN (mostly obscured) and star-forming galaxies associated with the cluster, while in the more external region this over-density is likely to be mostly due to background AGN. The fraction of cluster galaxies hosting an X-ray detected AGN is 1.0 ± 0.4%, which is nearly constant with the radius; this fraction is similar to that reported in other clusters of galaxies at similar redshift. The fraction of X-ray bright AGN (L2 − 10 keV > 1043 ergs s−1) in the region 0.3R200 < R < R200 is 0.5−0.2+0.6%, which is higher than that in other clusters at similar redshift and more similar to the AGN fraction in the field. Finally, the spatial distributions of AGN and star-forming galaxies, which we selected for their infrared emission, appear similar, thus suggesting that both are triggered by the same mechanism.

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Abrahamyan, Hayk V., und Areg M. Mickaelian. „Radio Properties of AGN“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 102–3. http://dx.doi.org/10.1017/s1743921314003469.

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AbstractTo study the radio properties of AGN, we cross-correlate and investigate Veron-Cetty & Veron catalog of QSOs and Active Galaxies (v.13, 2010) with a number of radio catalogs: NVSS, FIRST, GB6, 87GB, SUMSS, WISH, WENSS, and 7C. This catalog contains 168,940 objects with positional accuracy of mostly 1 arcsec, though many positions have larger errors. We use new cross-correlation software based on accuracy of each object independently. In this software we take into account errors for each source and take identifications with errors within 3 sigma. Altogether, we find ~16,000 AGN having radio detection in any of the listed catalogs. Using all data from radio catalogs, we derive a homogeneous sample of radio AGN. The sample allows accomplish several tasks, including study of the distribution of radio sources by activity types, differences in physical properties of radio-loud and radio-quiet AGN, luminosity functions for various types of radio AGN, study of the q parameter by AGN types and its evolution, etc.

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Travascio, A., A. Bongiorno, P. Tozzi, R. Fassbender, F. De Gasperin, V. F. Cardone, L. Zappacosta et al. „Multiple AGN activity during the BCG assembly of XDCPJ0044.0-2033 at z ∼ 1.6“. Monthly Notices of the Royal Astronomical Society 498, Nr. 2 (19.08.2020): 2719–33. http://dx.doi.org/10.1093/mnras/staa2495.

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ABSTRACT Undisturbed galaxy clusters are characterized by a massive and large elliptical galaxy at their centre, i.e. the brightest cluster galaxy (BCG). How these central galaxies form is still debated. According to most models, a typical epoch for their assembly is $z$ ∼ 1–2. We have performed a detailed multiwavelength analysis of the core of XMM–Newton Distant Cluster Project (XDCP) J0044.0-2033 (XDCP0044), one of the most massive and densest galaxy clusters currently known at redshift $z$ ∼ 1.6, whose central galaxy population shows high star formation compared to lower z clusters and an X-ray active galactic nuclei (AGN) located close to its centre. SINFONI J-, H-, and KMOS YJ-, H-bands spectroscopic data have been analysed, together with deep archival HST photometric data in F105W, F140W, and F160W bands, Chandra X-ray, radio JVLA data at 1–2 GHz, and ALMA band-6 observations. In the very central region of the cluster (∼70 kpc × 70 kpc), two systems of interacting galaxies have been identified and studied (Complex A and B), with a total of seven confirmed cluster members. These galaxies show perturbed morphologies and three of them show signs of AGN activity. In particular, two type-1 AGN with typical broad lines have been found at the centre of each complex (both of them X-ray obscured and highly accreting with $\rm \lambda _{Edd}\sim 0.4-0.6$), while a type-2 AGN has been discovered in Complex A. The AGN at the centre of Complex B is also detected in X-ray, while the other two are spatially related to radio emission. The three AGN provide one of the closest AGN triple at $z$ > 1 revealed so far with a minimum (maximum) projected distance of 10 (40) kpc. The observation of high star formation, merger signatures, and nuclear activity in the core of XDCP0044 suggests that all these processes are key ingredients in shaping the nascent BCG. According to our data, XDCP0044 could form a typical massive galaxy of $M_{\star }\sim 10^{12} \, \mathrm{M}_{\odot }$, hosting a black hole of $\rm 2 \times 10^8\!-\!10^9 \, \mathrm{M}_{\odot }$, in a time-scale of the order of ∼2.5 Gyr.

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Laporte, Nicolas, Kimihiko Nakajima, Richard S. Ellis, Adi Zitrin, Daniel P. Stark, Ramesh Mainali und G. W. Roberts-Borsani. „A Spectroscopic Search for AGN Activity in the Reionization Era“. Astrophysical Journal 851, Nr. 1 (08.12.2017): 40. http://dx.doi.org/10.3847/1538-4357/aa96a8.

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Blank, M., und W. J. Duschl. „Time lags between starburst and AGN activity in galaxy mergers“. Proceedings of the International Astronomical Union 9, S303 (Oktober 2013): 379–81. http://dx.doi.org/10.1017/s1743921314000957.

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AbstractWe show that the observed time lag between starburst and AGN activity can be explained by a viscous time lag the gas needs to flow through the AGN's accretion disk before reaching the central black hole. Our calculations reproduce the observed time lag and are in agreement with the observed correlation between black hole mass and stellar velocity dispersion.

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Irwin, Judith A., Philip Schmidt, A. Damas-Segovia, Rainer Beck, Jayanne English, George Heald, Richard N. Henriksen et al. „CHANG-ES – VIII. Uncovering hidden AGN activity in radio polarization“. Monthly Notices of the Royal Astronomical Society 464, Nr. 2 (23.09.2016): 1333–46. http://dx.doi.org/10.1093/mnras/stw2414.

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37

Hopkins, Philip F. „Dynamical delays between starburst and AGN activity in galaxy nuclei“. Monthly Notices of the Royal Astronomical Society: Letters 420, Nr. 1 (20.12.2011): L8—L12. http://dx.doi.org/10.1111/j.1745-3933.2011.01179.x.

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38

Jia, Zixian, Viktor Nadtochenko, Marina A. Radzig, Inessa A. Khmel, Gennadii Zavilgelsky, Rabah Azouani, Christine Mielcarek, Mounir Ben Amar, Mamadou Traore und Andrei Kanaev. „Antibacterial activity of monolayer nanoparticulate AgN-(titanium-oxo-alkoxy) coatings“. Mechanics & Industry 17, Nr. 5 (2016): 504. http://dx.doi.org/10.1051/meca/2015108.

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39

Giacintucci, S., T. Venturi, S. Bardelli, D. Dallacasa und E. Zucca. „AGN and starburst radio activity in the A3558 cluster complex“. Astronomy & Astrophysics 419, Nr. 1 (23.04.2004): 71–87. http://dx.doi.org/10.1051/0004-6361:20040071.

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40

Spinoglio, Luigi, und Juan Antonio Fernández-Ontiveros. „AGN types and unification model“. Proceedings of the International Astronomical Union 15, S356 (Oktober 2019): 29–43. http://dx.doi.org/10.1017/s1743921320002549.

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AbstractThe motivation of the “unified model” is to explain the main properties of the large zoo of active galactic nuclei with a single physical object. The discovery of broad permitted lines in the polarized spectrum of type 2 Seyfert galaxies in the mid 80’s led to the idea of an obscuring torus, whose orientation with respect to our line of sight was the reason of the different optical spectra. However, after many years of observations with different techniques, including IR and mm interferometry, the resulting properties of the observed dust structures differ from the torus model that would be needed to explain the type 1 vs type 2 dichotomy. Moreover, in the last years, multi-frequency monitoring of active galactic nuclei has shown an increasing number of transitions from one type to the other one, which cannot be explained in terms of the simple orientation of the dusty structure surrounding the active galactic nucleus (AGN). The interrelations between the AGN and the host galaxy, as also shown in the Magorrian relation, suggest that the evolution of the host galaxy may also have an important role in the observed manifestation of the nuclei. As an example, the observed delay between the maximum star formation activity and the onset of the AGN activity, and the higher occurrence of type 2 nuclei in star forming galaxies, have suggested the possible evolutionary path from, e.g., H II → AGN2 → AGN1. In the next years the models of unification need to also consider this observational framework and not only simple orientation effects.

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Bonzini, M., V. Mainieri, P. Padovani, K. I. Kellermann, N. Miller, P. Rosati, P. Tozzi und S. Vattakunnel. „Host galaxy properties of radio selected AGN“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 343–44. http://dx.doi.org/10.1017/s1743921314004244.

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AbstractWith the goal of investigating the link between black hole (BH) and star formation (SF) activity, we study a deep sample of radio selected star forming galaxies (SFGs) and active galactic nuclei (AGNs). Using a multi-wavelength approach we characterize their host galaxies properties (stellar masses, optical colors, and morphology). Moreover, comparing the star formation rate derived from the radio and far-infrared luminosity, we found evidences that the main contribution to the radio emission in the radio-quiet AGNs is star-formation activity in their host galaxy.

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Torbaniuk, O., M. Paolillo, F. Carrera, S. Cavuoti, C. Vignali, G. Longo und J. Aird. „The connection between star formation and supermassive black hole activity in the local Universe“. Monthly Notices of the Royal Astronomical Society 506, Nr. 2 (28.06.2021): 2619–37. http://dx.doi.org/10.1093/mnras/stab1794.

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ABSTRACT We study the nuclear (AGN) activity in the local Universe (z < 0.33) and its correlation with the host galaxy properties, derived from a Sloan Digital Sky Survey sample with spectroscopic star-formation rate (SFR) and stellar mass determination. To quantify the level of AGN activity we used the XMM-Newton Serendipitous Source Catalogue. Applying multiwavelength selection criteria (optical BPT-diagrams, X-ray/optical ratio etc), we found that 24 per cent of the detected sources are efficiently-accreting AGN with moderate-to-high X-ray luminosity, twice as likely to be hosted by star-forming galaxies than by quiescent ones. The distribution of the specific Black Hole accretion rate (λsBHAR) shows that nuclear activity in local, non-AGN dominated galaxies peaks at very low accretion rates (−4 ≲ log λsBHAR ≲ −3) in all stellar mass ranges. We observe systematically larger values of λsBHAR for galaxies with active star formation than for quiescent ones, and an increase of the mean λsBHAR with SFR for both star-forming and quiescent galaxies. These finding confirm the decrease in AGN activity with cosmic time and are consistent with a scenario where both star-formation and AGN activity are fuelled by a common gas reservoir.

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Koulouridis, Elias. „The AGN dependence on cluster mass“. Proceedings of the International Astronomical Union 14, S342 (Mai 2018): 145–48. http://dx.doi.org/10.1017/s1743921318005124.

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AbstractWe present the results of a study of the AGN density in a homogeneous and well studied sample of 167 bona-fide X-ray galaxy clusters (0.1<z<0.5). Our aim is to study the AGN activity in 167 XXL X-ray galaxy clusters as a function of the cluster mass and the location of the AGN in the cluster. We report a significant AGN excess in our low-mass cluster sub-sample between 0.5r500 and 2r500. In contrast, the high-mass sub-sample presents no AGN excess. The AGN excess in poor clusters indicates AGN triggering, supporting previous studies that reported enhanced galaxy merging in the cluster outskirts. This effect is probably prevented by high velocity dispersions in high-mass clusters. Comparing also with previous studies of massive or high-redshift clusters, we conclude that the AGN fraction in cluster galaxies anti-correlates strongly with cluster mass.

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Bongiorno, Angela, und Andrea Travascio. „The role of AGN activity in the building up of the BCG at z ∼ 1.6“. Proceedings of the International Astronomical Union 15, S356 (Oktober 2019): 280–84. http://dx.doi.org/10.1017/s1743921320003105.

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AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

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Kokotanekov, G., M. W. Wise, M. de Vries und H. T. Intema. „Signatures of multiple episodes of AGN activity in the core of Abell 1795“. Astronomy & Astrophysics 618 (Oktober 2018): A152. http://dx.doi.org/10.1051/0004-6361/201833222.

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In this paper we analyze AGN activity signatures in the rich nearby galaxy cluster Abell 1795 aiming to confirm and characterize the long-term feedback history in the system. We combine radio observations at 610 and 235 MHz from the Giant Metrewave Radio Telescope (GMRT) with 3.4 Msec X-ray data from the Chandra Observatory. Extracting radial temperature profiles, as well as X-ray and radio surface brightness profiles in three directions showing major morphological disturbances, we highlight the signatures of activity in the system. For the first time we observe radio emission corresponding to the NW X-ray depression, which provides evidence in favor of the classification of the depression as a cavity. We identify two other X-ray cavities situated NW and SW of the AGN. While the central radio emission corresponding to the inner cavities shows a flatter spectral index, the radio extensions associated with the farthest X-ray cavities consist of aged plasma. All observed signatures both in radio and X-ray are consistent with several consecutive episodes of AGN activity, which gave rise to the observed morphology NW and SW from the core. In the southern region, we confirm the cooling wake hypothesis for the origin of the long tail. The deep X-ray data also allows us to distinguish significant distortions in the tail’s inner parts, which we attribute to the activity of the AGN.

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Wamsteker, W., und R. Vio. „Multiwavelength Experiments on AGN: Reverberation Experiments“. Symposium - International Astronomical Union 159 (1994): 159–62. http://dx.doi.org/10.1017/s0074180900174959.

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The nature of the successful reverberation campaigns on variable active galaxies is summarized. A general summary of the completed campaigns is given. A discussion of the results of the first order (CCF) analysis is given and some comments are made on the directions needed to obtain more physcally meaningful solutions to the inversion problem presented by such observations of the sources of activity in the centers of active galaxies

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Hickox, Ryan C., Stephanie M. LaMassa, John D. Silverman und Alexander Kolodzig. „Host galaxies and large-scale structures of active galactic nuclei“. Proceedings of the International Astronomical Union 11, A29B (August 2015): 113–23. http://dx.doi.org/10.1017/s1743921316004592.

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AbstractOur understanding of the cosmic evolution of supermassive black holes (SMBHs) has been revolutionized by the advent of large multiwavelength extragalactic surveys, which have enabled detailed statistical studies of the host galaxies and large-scale structures of active galactic nuclei (AGN). We give an overview of some recent results on SMBH evolution, including the connection between AGN activity and star formation in galaxies, the role of galaxy mergers in fueling AGN activity, the nature of luminous obscured AGN, and the connection between AGN and their host dark matter halos. We conclude by looking to the future of large-scale extragalactic X-ray and spectroscopic surveys.

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Rosito, M. S., S. E. Pedrosa, P. B. Tissera, N. E. Chisari, R. Domínguez-Tenreiro, Y. Dubois, S. Peirani, J. Devriendt, C. Pichon und A. Slyz. „The role of AGN feedback in the structure, kinematics, and evolution of ETGs in Horizon simulations“. Astronomy & Astrophysics 652 (August 2021): A44. http://dx.doi.org/10.1051/0004-6361/202039976.

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Context. Feedback processes play a fundamental role in the regulation of the star formation (SF) activity in galaxies and, in particular, in the quenching of early-type galaxies (ETGs) as has been inferred by observational and numerical studies of Λ-CDM models. At z = 0, ETGs exhibit well-known fundamental scaling relations, but the connection between scaling relations and the physical processes shaping ETG evolution remains unknown. Aims. This work aims to study the impact of the energetic feedback due to active galactic nuclei (AGN) on the formation and evolution of ETGs. We focus on assessing the impact of AGN feedback on the evolution of the mass–plane and the fundamental plane (FP; defined using mass surface density) as well as on morphology, kinematics, and stellar age across the FP. Methods. The Horizon-AGN and Horizon-noAGN cosmological hydrodynamical simulations were performed with identical initial conditions, including the same physical processes except for the activation of the AGN feedback in the former. We selected a sample of central ETGs from both simulations using the same criteria and exhaustively studied their SF activity, kinematics, and scaling relations for z ≤ 3. Results. We find that Horizon-AGN ETGs identified at z = 0 follow the observed fundamental scaling relations (mass–plane, FP, and mass–size relation) and qualitatively reproduce kinematic features albeit conserving a rotational inner component with a mass fraction regulated by the AGN feedback. We discover that AGN feedback seems to be required to reproduce the bimodality in the spin parameter distribution reported by observational works and the mass–size relation; more massive galaxies have older stellar populations, larger sizes, and are slower rotators. We study the evolution of the fundamental relations with redshift, finding a mild evolution of the mass–plane of Horizon-AGN ETGs for z < 1, whereas a stronger change is detected for z > 1. The ETGs in Horizon-noAGN show a strong systematic redshift evolution of the mass–plane. The FP of Horizon-AGN ETGs agrees with observations at z = 0. When AGN feedback is switched off, a fraction of galaxies depart from the expected FP at all analysed redshifts owing to the presence of a few extended galaxies with an excess of stellar surface density. We find that AGN feedback regulates the SF activity as a function of stellar mass and redshift being able to reproduce the observed relations. Our results show the impact of AGN feedback on the mass-to-light ratio (M/L) and its relation with the tilt of the luminosity FP (L-FP; defined using the averaged surface brightness). Overall, AGN feedback has an impact on the regulation of the SF activity, size, stellar surface density, stellar ages, rotation, and masses of ETGs that is reflected on the fundamental relations, particularly on the FP. We detect a dependence of the FP on stellar age and galaxy morphology that evolves with redshfit. The characteristics of the galaxy distribution on the FP according to these properties change drastically by z ∼ 1 in Horizon-AGN and hence this feature could provide further insight into the action of AGN feedback.

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Sebastian, Biny, P. Kharb, C. P. O’Dea, J. F. Gallimore und S. A. Baum. „A radio polarimetric study to disentangle AGN activity and star formation in Seyfert galaxies“. Monthly Notices of the Royal Astronomical Society 499, Nr. 1 (19.08.2020): 334–54. http://dx.doi.org/10.1093/mnras/staa2473.

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ABSTRACT To understand the origin of radio emission in radio-quiet active galactic nucleus (AGN) and differentiate between the contributions from star formation, AGN accretion, and jets, we have observed a nearby sample of Seyfert galaxies along with a comparison sample of starburst galaxies using the Expanded Very Large Array (EVLA) in full-polarization mode in the B-array configuration. The radio morphologies of the Seyfert galaxies show lobe/bubble-like features or prominent cores in radio emission, whereas the starburst galaxies show radio emission spatially coincident with the star-forming regions seen in optical images. There is tentative evidence that Seyferts tend to show more polarized structures than starburst galaxies at the resolution of our observations. We find that unlike a sample of Seyfert galaxies hosting kilo-parsec scale radio (KSR) emission, starburst galaxies with superwinds do not show radio-excess compared to the radio–FIR correlation. This suggests that shock acceleration is not adequate to explain the excess radio emission seen in Seyferts and hence most likely have a jet-related origin. We also find that the [O iii] luminosity of the Seyferts is correlated with the off-nuclear radio emission from the lobes, whereas it is not well correlated with the total emission which also includes the core. This suggests strong jet–medium interaction, which in turn limits the jet/lobe extents in Seyferts. We find that the power contribution of AGN jet, AGN accretion, and star formation is more or less comparable in our sample of Seyfert galaxies. We also find indications of episodic AGN activity in many of our Seyfert galaxies.

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Vignali, Cristian. „Obscured accretion from AGN surveys“. Proceedings of the International Astronomical Union 9, S304 (Oktober 2013): 132–38. http://dx.doi.org/10.1017/s1743921314003548.

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AbstractRecent models of super-massive black hole (SMBH) and host galaxy joint evolution predict the presence of a key phase where accretion, traced by obscured Active Galactic Nuclei (AGN) emission, is coupled with powerful star formation. Then feedback processes likely self-regulate the SMBH growth and quench the star-formation activity. AGN in this important evolutionary phase have been revealed in the last decade via surveys at different wavelengths. On the one hand, moderate-to-deep X-ray surveys have allowed a systematic search for heavily obscured AGN, up to very high redshifts (z≈5). On the other hand, infrared/optical surveys have been invaluable in offering complementary methods to select obscured AGN also in cases where the nuclear X-ray emission below 10 keV is largely hidden to our view. In this review I will present my personal perspective of the field of obscured accretion from AGN surveys.

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