A hidden population of massive black holes in simulated dwarf galaxies

Abstract

We explore the characteristics of actively accreting MBHs within dwarf galaxies in the \textsc{Romulus25} cosmological hydrodynamic simulation. We examine the MBH occupation fraction, x-ray active fractions, and AGN scaling relations within dwarf galaxies of stellar mass $10^8<M_{\mathrm{star}}<10^{10}{M}_{\odot }$ out to redshift $z=2$. In the local universe, the MBH occupation fraction is consistent with observed constraints, dropping below unity at $M_{\mathrm{star}}<3\times 10^{10}{M}_{\odot }$, $M_{200}<3\times 10^{11}{M}_{\odot }$. Local dwarf AGN in \textsc{Romulus25} follow observed scaling relations between AGN x-ray luminosity, stellar mass, and star formation rate, though they exhibit slightly higher active fractions and number densities than comparable x-ray observations. Since $z=2$, the MBH occupation fraction has decreased, the population of dwarf AGN has become overall less luminous, and as a result, the overall number density of dwarf AGN has diminished. We predict the existence of a large population of MBHs in the local universe with low x-ray luminosities and high contamination from x-ray binaries and the hot interstellar medium that are undetectable by current x-ray surveys. These hidden MBHs make up $76\%$ of all MBHs in local dwarf galaxies, and include many MBHs that are undermassive relative to their host galaxy's stellar mass. Their detection relies not only on greater instrument sensitivity but on better modeling of x-ray contaminants or multi-wavelength surveys. Our results indicate dwarf AGN were substantially more active in the past despite being low-luminosity today, and indicate future deep x-ray surveys may uncover many hidden MBHs in dwarf galaxies out to at least $z=2$.

References in corpus (57)

• A luminous quasar at a redshift of z = 7.085
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• Formation of Supermassive Black Holes by Direct Collapse in Pregalactic Halos
• An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
• Star Formation and Feedback in Smoothed Particle Hydrodynamic Simulations--I. Isolated Galaxies
• Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
• The Illustris simulation: the evolving population of black holes across cosmic time
• Supermassive black hole formation during the assembly of pre-galactic discs
• Piecing Together the X-ray Background: Bolometric Corrections for Active Galactic Nuclei
• A New Sample of Low-mass Black Holes in Active Galaxies
• Formation of the first nuclear clusters and massive black holes at high redshift
• Obscuration-dependent evolution of Active Galactic Nuclei
• The dark nemesis of galaxy formation: why hot haloes trigger black hole growth and bring star formation to an end
• Observational evidence for intermediate-mass black holes
• Black Holes on FIRE: Stellar Feedback Limits Early Feeding of Galactic Nuclei
• Off the Beaten Path: A New Approach to Realistically Model The Orbital Decay of Supermassive Black Holes in Galaxy Formation Simulations
• Initial mass function of intermediate mass black hole seeds
• Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei And the First Black Hole Determination for NGC 205
• X-ray constraints on the local supermassive black hole occupation fraction
• Black Holes at the Centers of Nearby Dwarf Galaxies
• The erratic dynamical life of black hole seeds in high-redshift galaxies
• Spitzer Uncovers Active Galactic Nuclei Missed by Optical Surveys in 7 Late-type Galaxies
• Dark Matter Heating and Early Core Formation in Dwarf Galaxies
• Black hole mergers from dwarf to massive galaxies with the NewHorizon and Horizon-AGN simulations
• Hidden AGN in dwarf galaxies revealed by MaNGA: light echoes, off-nuclear wanderers, and a new broad-line AGN
• X-rays across the galaxy population I: tracing the main sequence of star formation
• An X-ray Selected Sample of Candidate Black Holes in Dwarf Galaxies
• X-ray Detected AGN in SDSS Dwarf Galaxies
• The Metallicity Dependence of the High-Mass X-ray Binary Luminosity Function
• Origins and Demographics of Wandering Black Holes
• AGN feedback in dwarf galaxies?
• A Sample of Massive Black Holes in Dwarf Galaxies Detected via [Fe X] Coronal Line Emission: Active Galactic Nuclei and/or Tidal Disruption Events
• Toward determining the number of observable supermassive black hole shadows
• Fast and energetic AGN-driven outflows in simulated dwarf galaxies
• An Accreting Black Hole in the Nuclear Star Cluster of the Bulgeless Galaxy NGC 1042
• The Origins of Off-Centre Massive Black Holes in Dwarf Galaxies
• Seeding Black Holes in Cosmological Simulations
• The birth of a supermassive black hole binary
• A Reverberation-Based Black Hole Mass for MCG-06-30-15
• The Incidence of X-ray selected AGN in Nearby Galaxies
• Compact massive objects in Virgo galaxies: the black hole population
• Unveiling the Population of Wandering Black Holes via Electromagnetic Signatures
• AGN and their host galaxies in the local Universe: two mass independent Eddington ratio distribution functions characterize black hole growth
• Type 2 AGN host galaxies in the Chandra-COSMOS Legacy Survey: No Evidence of AGN-driven Quenching
• Co-evolution of black hole accretion and star formation in galaxies up to z=3.5
• X-ray bolometric corrections for Compton-thick active galactic nuclei
• Extending Virial Black Hole Mass Estimates to Low-Luminosity or Obscured AGN: the cases of NGC 4395 and MCG -01-24-012
• Near-Infrared Coronal Line Observations of Dwarf Galaxies hosting AGN-driven Outflows
• A Low-Mass Black Hole in the Nearby Seyfert Galaxy UGC 06728
• A Chandra and HST View of WISE-Selected AGN Candidates in Dwarf Galaxies
• Hubble Space Telescope Imaging of the Active Dwarf Galaxy RGG 118
• Relics of Supermassive Black Hole Seeds: The Discovery of an Accreting Black Hole in an Optically Normal, Low Metallicity Dwarf Galaxy
• Outflows, Shocks and Coronal Line Emission in a Radio-Selected AGN in a Dwarf Galaxy
• Multi-wavelength observations of SDSS J105621.45+313822.1, a broad-line, low-metallicity AGN
• On the Prevalence of Super-Massive Black Holes over Cosmic Time
• Merger Histories and Environments of Dwarf AGN in IllustrisTNG

Cited by in corpus (4)

• Two can play at that game: constraining the role of supernova and AGN feedback in dwarf galaxies with cosmological zoom-in simulations
• Population statistics of intermediate mass black holes in dwarf galaxies using the NewHorizon simulation
• Dwarf AGNs from Variability for the Origins of Seeds (DAVOS): Intermediate-mass black hole demographics from optical synoptic surveys
• Orbital and Radiative Properties of Wandering Intermediate-Mass Black Holes in the ASTRID Simulation