scholarly journals Intermediate-mass black hole growth and feedback in dwarf galaxies at high redshifts

2019 ◽  
Vol 487 (4) ◽  
pp. 5549-5563 ◽  
Author(s):  
Paramita Barai ◽  
Elisabete M de Gouveia Dal Pino
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Formation Rate ◽  
Mass Range ◽  
Stellar Mass ◽  
Host Galaxies ◽  
Intermediate Mass ◽  
Hydrodynamical Simulations

Abstract Intermediate-mass black holes (IMBHs; masses between $100\rm{\, and \,}10^{6} \, \mathrm{M}_{\odot }$) historically comprise of an elusive population compared to stellar-mass and supermassive black holes (BHs). Recently, IMBHs have started to be observed at the centres of low-mass galaxies. We perform cosmological hydrodynamical simulations of $(2 \, h^{-1} ~ {\rm Mpc})^3$ comoving boxes and investigate the growth and feedback of central IMBHs in dwarf galaxies (DGs). The earliest BHs appear at z ∼ 18–25 and grow thereafter by accreting gas and by merger with other BHs. We find that, starting from $10^{2} \, \mathrm{M}_{\odot }$, it is possible to build up IMBHs of a few$\times 10^{5}\!-\!10^{6} \, \mathrm{M}_{\odot }$ by z = 5, when the BHs are seeded in haloes less massive than $4 \times 10^{7} \, \mathrm{M}_{\odot }$. The BH accretion rates increase with time and reach $\dot{M}_{\rm BH} = (0.2\!-\!0.8) \dot{M}_{\rm Edd}$ for the massive IMBHs by z = 4. The star formation rate density (SFRD) evolution of the DGs (stellar mass $10^{5}\!-\!10^{8} \, \mathrm{M}_{\odot }$) has a peak plateau between z = 4 and 6. Star formation is quenched between z = 9 and 4. The SFRD is reduced by factors up to 3 when the BHs have grown to a few times $10^5 \, \mathrm{M}_{\odot }$. Even in the presence of stronger supernova (SN)-driven mass ejection, the BHs continue to grow up to z ∼ 6, sustained by gas inflows driven by galaxy mergers and interactions in a cosmological environment. Our conclusions, based on numerical simulation results, support the scenario that early feedback from IMBHs in gas-rich DGs at z = 5–8 can potentially solve several anomalies in the DG mass range within the concordance Λ cold dark matter (ΛCDM) cosmological scenario (Silk 2017). Our results suggest that IMBHs at DG centres grow faster than their host galaxies in the early Universe, and the resulting BH feedback turns the DGs and the BHs dormant.

scholarly journals Intermediate-Mass Black Hole Feedback in Dwarf Galaxies: a View from Cosmological Simulations

2018 ◽  
Vol 14 (S342) ◽  
pp. 154-157
Author(s):  
Paramita Barai ◽  
Elisabete M. de Gouveia Dal Pino
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Natural Extension ◽  
Stellar Mass ◽  
Intermediate Mass ◽  
Strong Source ◽  
Hydrodynamical Simulations

AbstractBlack holes are usually observed to be of stellar-mass or supermassive. By natural extension, there should be a population of Intermediate-Mass Black Holes (IMBHs: with mass between 100 to 106M⊙) in the Universe; which has started to been observed. An exciting claim has been made recently by Silk (2017): that early feedback by IMBHs in gas-rich dwarf galaxies at z = 5–8, can potentially solve multiple dwarf galaxy problems within the Λ-cold-dark-matter cosmology. We are performing Cosmological Hydrodynamical Simulations of (2Mpc)3 volumes, starting from z = 100, to test the case for IMBHs in Dwarf Galaxies. Black holes of mass 1000M⊙ are seeded inside halos when they reach a mass of 107M⊙. The black holes grow by accretion of gas from their surroundings and by merger with other black holes, and consequently eject feedback energy. We analyze the simulation output in post-processing to study the growth of the first IMBHs, and their impact on star-formation. Our conclusions, based on numerical simulation results, support the phenomenological ideas made by Silk (2017). IMBHs at the centers of dwarf galaxies can be a strong source of feedback to quench star-formation and generate outflows. At the same time, these IMBHs form the missing link between stellar-mass and supermassive BHs.

scholarly journals Multiwavelength morphological study of active galaxies

2019 ◽  
Vol 15 (S356) ◽  
pp. 295-298
Author(s):  
Betelehem Bilata-Woldeyes ◽  
Mirjana Pović ◽  
Zeleke Beyoro-Amado ◽  
Tilahun Getachew-Woreta ◽  
Shimeles Terefe
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Active Galaxies ◽  
Morphological Properties ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
Public Data

AbstractStudying the morphology of a large sample of active galaxies at different wavelengths and comparing it with active galactic nuclei (AGN) properties, such as black hole mass (MBH) and Eddington ratio (λEdd), can help us in understanding better the connection between AGN and their host galaxies and the role of nuclear activity in galaxy formation and evolution. By using the BAT-SWIFT hard X-ray public data and by extracting those parameters measured for AGN and by using other public catalogues for parameters such as stellar mass (M*), star formation rate (SFR), bolometric luminosity (Lbol), etc., we studied the multiwavelength morphological properties of host galaxies of ultra-hard X-ray detected AGN and their correlation with other AGN properties. We found that ultra hard X-ray detected AGN can be hosted by all morphological types, but in larger fractions (42%) they seem to be hosted by spirals in optical, to be quiet in radio, and to have compact morphologies in X-rays. When comparing morphologies with other galaxy properties, we found that ultra hard X-ray detected AGN follow previously obtained relations. On the SFR vs. stellar mass diagram, we found that although the majority of sources are located below the main sequence (MS) of star formation (SF), still non-negligible number of sources, with diverse morphologies, is located on and/or above the MS, suggesting that AGN feedback might have more complex influence on the SF in galaxies than simply quenching it, as it was suggested in some of previous studies.

scholarly journals The diversity and variability of star formation histories in models of galaxy evolution

2020 ◽  
Vol 498 (1) ◽  
pp. 430-463 ◽  
Author(s):  
Kartheik G Iyer ◽  
Sandro Tacchella ◽  
Shy Genel ◽  
Christopher C Hayward ◽  
Lars Hernquist ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Time Scales ◽  
Formation Rate ◽  
Power Laws ◽  
Stellar Mass ◽  
Physical Processes ◽  
Long Time ◽  
Hydrodynamical Simulations ◽  
Star Formation Histories

ABSTRACT Understanding the variability of galaxy star formation histories (SFHs) across a range of time-scales provides insight into the underlying physical processes that regulate star formation within galaxies. We compile the SFHs of galaxies at z = 0 from an extensive set of models, ranging from cosmological hydrodynamical simulations (Illustris, IllustrisTNG, Mufasa, Simba, EAGLE), zoom simulations (FIRE-2, g14, and Marvel/Justice League), semi-analytic models (Santa Cruz SAM) and empirical models (UniverseMachine), and quantify the variability of these SFHs on different time-scales using the power spectral density (PSD) formalism. We find that the PSDs are well described by broken power laws, and variability on long time-scales (≳1 Gyr) accounts for most of the power in galaxy SFHs. Most hydrodynamical models show increased variability on shorter time-scales (≲300 Myr) with decreasing stellar mass. Quenching can induce ∼0.4−1 dex of additional power on time-scales >1 Gyr. The dark matter accretion histories of galaxies have remarkably self-similar PSDs and are coherent with the in situ star formation on time-scales >3 Gyr. There is considerable diversity among the different models in their (i) power due to star formation rate variability at a given time-scale, (ii) amount of correlation with adjacent time-scales (PSD slope), (iii) evolution of median PSDs with stellar mass, and (iv) presence and locations of breaks in the PSDs. The PSD framework is a useful space to study the SFHs of galaxies since model predictions vary widely. Observational constraints in this space will help constrain the relative strengths of the physical processes responsible for this variability.

scholarly journals ENVIRONMENTAL DEPENDENCE OF AGE, STELLAR MASS, STAR FORMATION RATE AND STELLAR VELOCITY DISPERSION OF ACTIVE GALACTIC NUCLEUS HOST GALAXIES

2021 ◽  
Vol 57 (1) ◽  
pp. 157-166
Author(s):  
Xin-Fa Deng ◽  
Xiao-Qing Wen
Keyword(s):  
Star Formation ◽  
Active Galactic Nucleus ◽  
Velocity Dispersion ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Apparent Magnitude ◽  
Host Galaxies ◽  
Stellar Velocity ◽  
Environmental Dependence

Using the apparent-magnitude limited active galactic nucleus (AGN) host galaxy sample of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12), we investigate the environmental dependence of age, stellar mass, the star formation rate (SFR) and stellar velocity dispersion of AGN host galaxies. We divide the whole apparent-magnitude limited AGN sample into many subsamples with a redshift binning size of Δz = 0.01, and analyse the environmental dependence of these galaxy properties of subsamples in each redshift bin. It turns out that these parameters of AGN host galaxies seemingly only have a weak environmental dependence.

scholarly journals The dependence of AGN activity on environment in SDSS

2019 ◽  
Vol 488 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Zhong-yi Man ◽  
Ying-jie Peng ◽  
Xu Kong ◽  
Ke-xin Guo ◽  
Cheng-peng Zhang ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Minor Role ◽  
Host Galaxies ◽  
Star Forming ◽  
Secular Evolution ◽  
Intrinsic Correlation ◽  
Merger Rate ◽  
A Minor

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.

scholarly journals The build-up of the outskirts of distant star-forming galaxies at z ~ 2

2016 ◽  
Vol 11 (S321) ◽  
pp. 327-329 ◽  
Author(s):  
Sandro Tacchella ◽  
C. Marcella Carollo ◽  
Avishai Dekel ◽  
Natascha Förster Schreiber ◽  
Alvio Renzini ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Mass Star ◽  
Intermediate Mass ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
Dust Attenuation ◽  
Inside Out

AbstractIn order to constrain – and understand – the growth of galaxies, we present a sample of ~ 30 galaxies at z ~ 2 with resolved distribution of stellar mass, star-formation rate, and dust attenuation on scales of ~ 1 kpc. We find that low- and intermediate-mass galaxies grow self-similarly, doubling their stellar mass in the centers and outskirts with the same pace. More massive galaxies (~ 1011 M⊙) have a reduced star-formation activity in their center: they grow mostly in the outskirts (inside-out quenching / formation). Similar trends are find in cosmological zoom-in simulations, highlighting that high stellar mass densities are formed in a gas-rich compaction phase. This nuclear ‘starburst’ phase is followed by a suppressed star-formation activity in the center, resulting in growth of the outskirts. All in all, we put forward that we witness at z ~ 2 the dissipative formation of z = 0 M* early-type galaxies.

scholarly journals AlFoCS + Fornax3D: resolved star formation in the Fornax cluster with ALMA and MUSE

2020 ◽  
Vol 496 (2) ◽  
pp. 2155-2182 ◽  
Author(s):  
N Zabel ◽  
T A Davis ◽  
M Sarzi ◽  
Boris Nedelchev ◽  
M Chevance ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Formation Rate ◽  
Mass Range ◽  
Stellar Mass ◽  
Small Scale ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Cluster Galaxies ◽  
Fornax Cluster

ABSTRACT We combine data from ALMA and MUSE to study the resolved (∼300 pc scale) star formation relation (star formation rate, SFR, versus molecular gas surface density) in cluster galaxies. Our sample consists of nine Fornax cluster galaxies, including spirals, ellipticals, and dwarfs, covering a stellar mass range of ∼108.8–1011 M⊙. CO(1-0) and extinction corrected Hα were used as tracers for the molecular gas mass and SFR, respectively. We compare our results with Kennicutt and Bigiel et al. Furthermore, we create depletion time maps to reveal small-scale variations in individual galaxies. We explore these further in FCC290, using the ‘uncertainty principle for star formation’ (Kruijssen & Longmore) to estimate molecular cloud lifetimes, which we find to be short (<10 Myr) in this galaxy. Galaxy-averaged depletion times are compared with other parameters such as stellar mass and cluster-centric distance. We find that the star formation relation in the Fornax cluster is close to those from Kennicutt and Bigiel et al., but overlaps mostly with the shortest depletion times predicted by Bigiel et al. This slight decrease in depletion time is mostly driven by dwarf galaxies with disturbed molecular gas reservoirs close to the virial radius. In FCC90, a dwarf galaxy with a molecular gas tail, we find that depletion times are a factor ≳10 higher in its tail than in its stellar body.

scholarly journals Feedback from central massive black holes in galaxies using cosmological simulations

2019 ◽  
Vol 15 (S359) ◽  
pp. 35-36
Author(s):  
Paramita Barai
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Galaxy Evolution ◽  
Supermassive Black Holes ◽  
Active Galaxies ◽  
Host Galaxies ◽  
Massive Black Holes ◽  
Energy Feedback ◽  
Hydrodynamical Simulations ◽  
Gas Accretion

AbstractGas accretion onto central supermassive black holes of active galaxies and resulting energy feedback, is an important component of galaxy evolution, whose details are still unknown especially at early cosmic epochs. We investigate BH growth and feedback in quasar-host galaxies at z ⩾ 6 by performing cosmological hydrodynamical simulations. We simulate the 2R200 region around a 2 × 1012Mʘ halo at z = 6, inside a (500 Mpc)3 comoving volume, using the zoom-in technique. We find that BHs accrete gas at the Eddington rate over z = 9–6. At z = 6, our most-massive BH has grown to MBH = 4 × 109 Mʘ. Star-formation is quenched over z = 8–6.

scholarly journals The distinct stellar metallicity populations of simulated Local Group dwarfs

2019 ◽  
Vol 488 (2) ◽  
pp. 2312-2331 ◽  
Author(s):  
Anna Genina ◽  
Carlos S Frenk ◽  
Alejandro Benítez-Llambay ◽  
Shaun Cole ◽  
Julio F Navarro ◽  
...  
Keyword(s):  
Star Formation ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Mass Range ◽  
Spatial Segregation ◽  
Ram Pressure ◽  
History Of ◽  
Hydrodynamical Simulations ◽  
Two Populations ◽  
Poor Population

ABSTRACT A number of Local Group dwarf galaxies are known to have two spatially segregated stellar metallicity populations, a centrally concentrated metal-rich population, and a more extended metal-poor population. In this work we discuss mechanisms that lead to the formation of two spatially segregated metallicity populations. Using a set of high-resolution hydrodynamical simulations of Local Group-like environments, we select a sample of satellite and field galaxies, spanning the stellar mass range 106–109 M⊙, that exhibit bimodality in their metallicity distributions. Among those, we identify a subsample with a strong spatial segregation in the two populations. We find three distinct mechanisms for their formation. In field dwarfs and in a small fraction of satellites, a merger causes the metal-poor stars to migrate to larger radii and encourages the available gas to sink to the centre of the dwarf. Most of the gas is subsequently blown out of the halo through star formation feedback, but the remaining gas is consumed in the formation of a metal-rich population. In the exclusive case of satellites that have retained some of their gas at infall, it is the compression of this gas by ram pressure near pericentre that triggers the formation of metal-rich stars, whilst simultaneously preventing star formation at larger radii through stripping. Additionally, in a small number of field and satellite dwarfs, interactions with gaseous filaments and other galaxies can result in the formation of a metal-rich population. Regardless of the formation mechanism, a history of mergers typically enhances the spatial segregation.

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