Identifying Direct Collapse Black Hole Seeds through their Small Host Galaxies

Abstract

Observations of high-redshift quasars indicate that super massive black holes (SMBHs) with masses greater than $\sim 10^9{M}_{\odot }$ were assembled within the first billion years after the Big Bang. It is unclear how such massive black holes formed so early. One possible explanation is that these SMBHs were seeded by `heavy' direct collapse black holes (DCBHs) with masses of $M_{\mathrm{BH}}\approx 10^5{M}_{\odot }$, but observations have not yet confirmed or refuted this scenario. In this Letter, we utilize a cosmological N-body simulation to demonstrate that before they grow roughly an order of magnitude in mass, DCBHs will have black hole mass to halo mass ratios much higher than expected for black hole remnants of Population III (Pop III) stars which have grown to the same mass ($\sim 10^6{M}_{\odot }$). We also show that when $T_{\mathrm{vir}}\approx 10^4\mathrm{K}$ halos (the potential sites of DCBH formation) merge with much larger nearby halos ($M_{\mathrm{h}}>10^{10}{M}_{\odot }$), they almost always orbit their larger host halos with a separation of a few kpc, which is sufficient to be spatially resolved with future X-ray and infrared telescopes. Thus, we propose that a future X-ray mission such as Lynx combined with infrared observations will be able to distinguish high-redshift DCBHs from smaller black hole seeds due to the unusually high black hole mass to stellar mass ratios of the faintest observed quasars, with inferred BH masses below $\sim 10^6{M}_{\odot }$.

7 pages, 3 figures, accepted by ApJL

References in corpus (18)

• A luminous quasar at a redshift of z = 7.085
• An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
• Transients from Initial Conditions in Cosmological Simulations
• Direct cosmological simulations of the growth of black holes and galaxies
• Supermassive black hole formation during the assembly of pre-galactic discs
• The evolution of massive black hole seeds
• Primordial Star Formation under the Influence of Far Ultraviolet Radiation: 1540 Cosmological Halos and the Stellar Mass Distribution
• Accretion onto the First Stellar Mass Black Holes
• Fluctuations in the High-Redshift Lyman-Werner Background: Close Halo Pairs as the Origin of Supermassive Black Holes
• SubHaloes going Notts: The SubHalo-Finder Comparison Project
• Feedback-regulated Super Massive Black Hole Seed Formation
• Accretion onto Intermediate-Mass Black Holes in Dense Protogalactic Clouds
• Supersonic Gas Streams Enhance the Formation of Massive Black Holes in the Early Universe
• Direct collapse black hole formation from synchronized pairs of atomic cooling halos
• Conditions for Optimal Growth of Black Hole Seeds
• Seeding Black Holes in Cosmological Simulations
• Massive black hole and Population III galaxy formation in over-massive dark matter halos with violent merger histories
• Radiative effects during the assembly of direct collapse black holes

Cited by in corpus (12)

• JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty
• JWST CEERS & JADES Active Galaxies at z = 4-7 Violate the Local $M_{\bullet }-M_{\star }$ Relation at $>3\sigma$: Implications for Low-Mass Black Holes and Seeding Models
• Titans of the Early Universe: The Prato Statement on the Origin of the First Supermassive Black Holes
• The Redshift Evolution of the $M_{\bullet }-M_{\star }$ Relation for JWST's Supermassive Black Holes at $z>4$
• Supercritical growth pathway to overmassive black holes at cosmic dawn: coevolution with massive quasar hosts
• How long do high-redshift massive black hole seeds remain outliers in black hole vs. host galaxy relations?
• Properties and merger signatures of galaxies hosting LISA coalescing massive black hole binaries
• JADES reveals a large population of low mass black holes at high redshift
• Surveying the onset and evolution of supermassive black holes at high-z with AXIS
• Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds
• Detection of Tidal Disruption Events around Direct Collapse Black Holes at High Redshifts with the James Webb Space Telescope
• Black Hole merger rates in the first billion years in light of JWST data