The role of Active Galactic Nuclei feedback in the formation of the brightest cluster galaxies

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.

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Excitation mechanism in the intracluster filaments surrounding the Brightest Cluster Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002343 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 185-187

Author(s):

Fiorella L. Polles

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Elliptical Galaxies ◽

Cluster Galaxies ◽

Cooling Flow ◽

Submillimeter Wavelengths ◽

Hot Plasma ◽

Brightest Cluster Galaxies ◽

Multi Phase ◽

The Impact

AbstractMulti-phase filamentary structures surrounding giant elliptical galaxies at the center of cool-core clusters, the Brightest Cluster Galaxies (BCGs), have been detected from optical to submillimeter wavelengths. The source of the ionisation in the filaments is still debated. Studying the excitation of these structures is key to our understanding of Active Galactic Nuclei (AGN) feedback in general, and more precisely of the impact of environmental and local effects on star formation. One possible contributor to the excitation of the filaments is the thermal radiation from the cooling of the hot plasma surrounding the BCGs, the so-called cooling flow.

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Rapid early coeval star formation and assembly of the most-massive galaxies in the Universe

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa541 ◽

2020 ◽

Vol 493 (4) ◽

pp. 4607-4621 ◽

Cited By ~ 2

Author(s):

Douglas Rennehan ◽

Arif Babul ◽

Christopher C Hayward ◽

Connor Bottrell ◽

Maan H Hani ◽

...

Keyword(s):

Stellar Mass ◽

Cluster Galaxies ◽

Massive Galaxies ◽

James Webb Space Telescope ◽

Brightest Cluster Galaxies ◽

Virial Mass ◽

Formation And Evolution ◽

Hydrodynamical Simulations ◽

Observational Techniques ◽

Near Future

Abstract The current consensus on the formation and evolution of the brightest cluster galaxies is that their stellar mass forms early ($z$ ≳ 4) in separate galaxies that then eventually assemble the main structure at late times ($z$ ≲ 1). However, advances in observational techniques have led to the discovery of protoclusters out to $z$ ∼ 7. If these protoclusters assemble rapidly in the early Universe, they should form the brightest cluster galaxies much earlier than suspected by the late-assembly picture. Using a combination of observationally constrained hydrodynamical and dark-matter-only simulations, we show that the stellar assembly time of a sub-set of brightest cluster galaxies occurs at high redshifts ( $z$ > 3) rather than at low redshifts ($z$ < 1), as is commonly thought. We find, using isolated non-cosmological hydrodynamical simulations, that highly overdense protoclusters assemble their stellar mass into brightest cluster galaxies within ∼1 Gyr of evolution – producing massive blue elliptical galaxies at high redshifts ($z$ ≳ 1.5). We argue that there is a downsizing effect on the cluster scale wherein some of the brightest cluster galaxies in the cores of the most-massive clusters assemble earlier than those in lower mass clusters. In those clusters with $z$ = 0 virial mass ≥ 5 × 1014 M⊙, we find that $9.8{{\ \rm per\ cent}}$ have their cores assembly early, and a higher fraction of $16.4{{\ \rm per\ cent}}$ in those clusters above 1015 M⊙. The James Webb Space Telescope will be able to detect and confirm our prediction in the near future, and we discuss the implications to constraining the value of σ8.

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Ubiquitous cold and massive filaments in brightest cluster galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002355 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 182-184

Author(s):

Valeria Olivares ◽

Philippe Salomé

Keyword(s):

Life Cycle ◽

Numerical Simulations ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Cluster Galaxies ◽

Brightest Cluster Galaxies ◽

Radial Extent ◽

Cold Gas

AbstractThe origin of the mysterious multiphase filamentary structures surrounding Brightest Cluster Galaxies (BCGs) remains unknown. We present Atacama Large Millimeter/submillimeter Array (ALMA) and Multi Unit Spectroscopic Explorer (MUSE) observations for a sample of 15 BCGs to investigate the origin and life-cycle of the gas. Those observations show clumpy and massive molecular filaments, preferentially located around the radio bubbles inflated by the active galactic nuclei (AGN). We investigate where the cold gas condenses from the intra-cluster medium, by comparing the radial extent of the filaments with predictions from numerical simulations.

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AGN jet feedback on a moving mesh: lobe energetics and X-ray properties in a realistic cluster environment

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2604 ◽

2019 ◽

Vol 490 (1) ◽

pp. 343-349 ◽

Cited By ~ 5

Author(s):

Martin A Bourne ◽

Debora Sijacki ◽

Ewald Puchwein

Keyword(s):

Active Galactic Nuclei ◽

Galaxy Cluster ◽

Galactic Nuclei ◽

Moving Mesh ◽

X Ray ◽

Cluster Galaxies ◽

Hot Gas ◽

Brightest Cluster Galaxies ◽

Cluster Environment ◽

Very High

ABSTRACT Jet feedback from active galactic nuclei (AGN) harboured by brightest cluster galaxies is expected to play a fundamental role in regulating cooling in the intracluster medium (ICM). While observations and theory suggest energy within jet lobes balances ICM radiative losses, the modus operandi of energy communication with the ICM remains unclear. We present simulations of very high resolution AGN-driven jets launching in a live, cosmological galaxy cluster, within the moving mesh code arepo. As the jet propagates through the ICM the majority of its energy, which is initially in the kinetic form, thermalizes quickly through internal shocks and inflates lobes of very hot gas. The jets effectively heat the cluster core, with PdV work and weather-aided mixing being the main channels of energy transfer from the lobes to the ICM, while strong shocks and turbulence are subdominant. We additionally present detailed mock X-ray maps at different stages of evolution, revealing clear cavities surrounded by X-ray bright rims, with lobes being detectable for up to ∼108 yr even when magnetic draping is ineffective. We find bulk motions in the cluster can significantly affect lobe propagation, offsetting them from the jet direction and imparting bulk velocities that can dominate over the buoyantly rising motion.

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The K-Band Hubble Diagram for the Brightest Cluster Galaxies: A Test of Galaxy Formation Models

Symposium - International Astronomical Union ◽

10.1017/s007418090011321x ◽

1999 ◽

Vol 186 ◽

pp. 407-407

Author(s):

A. Aragón-Salamanca ◽

C.M. Baugh ◽

G. Kauffmann

Keyword(s):

Galaxy Formation ◽

Stellar Mass ◽

Hubble Diagram ◽

Redshift Range ◽

Cluster Galaxies ◽

Brightest Cluster Galaxies ◽

Galaxy Formation And Evolution ◽

Absolute Magnitudes ◽

Luminosity Evolution ◽

K Band

We analyze the K-band Hubble diagram for a sample of brightest cluster galaxies (BCGs) in the redshift range 0 < z < 1. We confirm that the scatter in the absolute magnitudes of the galaxies is small (0.3 magnitudes). The BCGs exhibit very little luminosity evolution in this redshift range: if q0 = 0.0 we detect no luminosity evolution; for q0 = 0.5 we measure a small negative evolution (i.e., BCGs were about 0.5 magnitudes fainter at z = 1 than today). If the mass in stars of these galaxies had remained constant over this period of time, substantial positive luminosity evolution would be expected: BCGs should have been brighter in the past since their stars were younger. A likely explanation for the observed zero or negative evolution is that the stellar mass of the BCGs has been assembled over time through merging and accretion, as expected in hierarchical models of galaxy formation. The colour evolution of the BCGs is consistent with that of an old stellar population (zform > 2) that is evolving passively. We can thus use evolutionary population synthesis models to estimate the rate of growth in stellar mass for these systems. We find that the stellar mass in a typical BCG has grown by a factor ≃ 2 since z ≃ 1 if q0 = 0.0 or by factor ≃ 4 if q0 = 0.5. These results are in remarkably good agreement with the predictions of semi-analytic models of galaxy formation and evolution set in the context of a hierarchical scenario for structure formation.

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Role of environment on AGN activity

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002835 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 171-171

Author(s):

Amirnezam Amiri

Keyword(s):

Star Formation ◽

Active Galactic Nuclei ◽

Galaxy Clusters ◽

Galactic Nuclei ◽

Stellar Mass ◽

Local Universe ◽

Nuclear Activity ◽

Star Forming ◽

Star Formation Activity

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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