@article{17507, abstract = {Stellar-mass black holes (BHs) are predicted to be embedded in the disks of active galactic nuclei (AGNs) due to gravitational drag and in situ star formation. However, clear evidence for AGN disk-embedded BHs is currently lacking. Here, as possible electromagnetic signatures of these BHs, we investigate breakout emission from shocks emerging around Blandford–Znajek jets launched from accreting BHs in AGN disks. We assume that most of the highly super-Eddington flow reaches the BH and produces a strong jet, and the jet produces feedback that shuts off accretion and thus leads to episodic flaring. These assumptions, while poorly understood at present, yield observable consequences that can probe the presence of AGN-embedded BHs as well as the accretion process itself. They predict a breakout emission characterized by luminous thermal emission in the X-ray bands and bright broadband nonthermal emission from the infrared to the gamma-ray bands. The flare duration depends on the BH's distance r from the central supermassive BH, varying between 103–106 s for r ∼ 0.01–1 pc. This emission can be discovered by current and future infrared, optical, and X-ray wide-field surveys and monitoring campaigns of nearby AGNs.}, author = {Tagawa, Hiromichi and Kimura, Shigeo S. and Haiman, Zoltán and Perna, Rosalba and Bartos, Imre}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {1}, publisher = {American Astronomical Society}, title = {{Observable signatures of stellar-mass black holes in active galactic nuclei}}, doi = {10.3847/2041-8213/acc103}, volume = {946}, year = {2023}, } @article{17513, abstract = {The astrophysical origin of over 90 compact binary mergers discovered by the LIGO and Virgo gravitational wave observatories is an open question. While the unusual mass and spin of some of the discovered objects constrain progenitor scenarios, the observed mergers are consistent with multiple interpretations. A promising approach to solve this question is to consider the observed distributions of binary properties and compare them to expectations from different origin scenarios. Here we describe a new hierarchical population analysis framework to assess the relative contribution of different formation channels simultaneously. For this study we considered binary formation in active galactic nucleus (AGN) disks along with phenomenological models, but the same framework can be extended to other models. We find that high-mass and high-mass-ratio binaries appear more likely to have an AGN origin compared to having the same origin as lower-mass events. Future observations of high-mass black hole mergers could further disentangle the AGN component from other channels.}, author = {Gayathri, V. and Wysocki, Daniel and Yang, Y. and Delfavero, Vera and O’Shaughnessy, R. and Haiman, Zoltán and Tagawa, H. and Bartos, I.}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {American Astronomical Society}, title = {{Gravitational wave source populations: Disentangling an AGN component}}, doi = {10.3847/2041-8213/acbfb8}, volume = {945}, year = {2023}, } @article{17514, abstract = {Extreme mass-ratio inspirals (EMRIs) take place when a stellar-mass black hole (BH) merges with a supermassive BH (SMBH). The gravitational-wave emission from such an event is expected to be detectable by the future Laser Interferometer Space Antenna (LISA) and other millihertz detectors. It was recently suggested that the EMRI rate in SMBH binary systems is orders of magnitude higher than the EMRI rate around a single SMBH with the same total mass. Here we show that this high rate can produce thousands of SMBH–BH sources at a redshift of unity. We predict that LISA may detect a few hundred of these EMRIs with signal-to-noise ratio above S/N ≥8 within a 4 yr mission lifetime. The remaining subthreshold sources will contribute to a large confusion noise, which is approximately an order of magnitude above LISA’s sensitivity level. Finally, we suggest that the individually detectable systems, as well as the background noise from the subthreshold EMRIs, can be used to constrain the SMBH binary fraction in the low-redshift Universe.}, author = {Naoz, Smadar and Haiman, Zoltán}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {American Astronomical Society}, title = {{The enhanced population of extreme mass-ratio inspirals in the LISA band from supermassive black hole binaries}}, doi = {10.3847/2041-8213/acf8c9}, volume = {955}, year = {2023}, } @article{17549, abstract = {Studies of rest-frame optical emission in quasars at z>6 have historically been limited by the wavelengths accessible by ground-based telescopes. The James Webb Space Telescope (JWST) now offers the opportunity to probe this emission deep into the reionization epoch. We report the observations of eight quasars at z>6.5 using the JWST/NIRCam Wide Field Slitless Spectroscopy, as a part of the ''A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE)" program. Our JWST spectra cover the quasars' emission between rest frame ∼ 4100 and 5100 Å. The profiles of these quasars' broad Hβ emission lines span a FWHM from 3000 to 6000 km s−1. The Hβ-based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion solar masses, are generally consistent with their MgII-based BH masses. The new measurements based on the more reliable Hβ tracer thus confirm the existence of billion solar-mass BHs in the reionization epoch. In the observed [OIII] λλ4960,5008 doublets of these luminous quasars, broad components are more common than narrow core components (≤ 1200 km s−1), and only one quasar shows stronger narrow components than broad. Two quasars exhibit significantly broad and blueshifted [OIII] emission, thought to trace galactic-scale outflows, with median velocities of −610 km s−1 and −1430 km s−1 relative to the [CII] 158μm line. All eight quasars show strong optical FeII emission, and follow the Eigenvector 1 relations defined by low-redshift quasars. The entire ASPIRE program will eventually cover 25 quasars and provide a statistical sample for the studies of the BHs and quasar spectral properties.}, author = {Yang, Jinyi and Wang, Feige and Fan, Xiaohui and Hennawi, Joseph F. and Barth, Aaron J. and Bañados, Eduardo and Sun, Fengwu and Liu, Weizhe and Cai, Zheng and Jiang, Linhua and Li, Zihao and Onoue, Masafusa and Schindler, Jan-Torge and Shen, Yue and Wu, Yunjing and Bhowmick, Aklant K. and Bieri, Rebekka and Blecha, Laura and Bosman, Sarah and Champagne, Jaclyn B. and Colina, Luis and Connor, Thomas and Costa, Tiago and Davies, Frederick B. and Decarli, Roberto and De Rosa, Gisella and Drake, Alyssa B. and Egami, Eiichi and Eilers, Anna-Christina and Evans, Analis E. and Farina, Emanuele Paolo and Habouzit, Melanie and Haiman, Zoltán and Jin, Xiangyu and Jun, Hyunsung D. and Kakiichi, Koki and Khusanova, Yana and Kulkarni, Girish and Loiacono, Federica and Lupi, Alessandro and Mazzucchelli, Chiara and Pan, Zhiwei and Rojas-Ruiz, Sofía and Strauss, Michael A. and Tee, Wei Leong and Trakhtenbrot, Benny and Trebitsch, Maxime and Venemans, Bram and Vestergaard, Marianne and Volonteri, Marta and Walter, Fabian and Xie, Zhang-Liang and Yue, Minghao and Zhang, Haowen and Zhang, Huanian and Zou, Siwei}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {1}, publisher = {American Astronomical Society}, title = {{A SPectroscopic survey of biased halos in the reionization Era (ASPIRE): A first look at the rest-frame optical spectra of > 6.5 quasars using JWST}}, doi = {10.3847/2041-8213/acc9c8}, volume = {951}, year = {2023}, } @article{17606, abstract = {We present the first results from the JWST ASPIRE program (A SPectroscopic survey of biased halos In the Reionization Era). This program represents an imaging and spectroscopic survey of 25 reionization-era quasars and their environments by utilizing the unprecedented capabilities of NIRCam Wide Field Slitless Spectroscopy (WFSS) mode. ASPIRE will deliver the largest (∼280 arcmin^2) galaxy redshift survey at 3-4 μm among JWST Cycle-1 programs and provide extensive legacy values for studying the formation of the earliest supermassive black holes (SMBHs), the assembly of galaxies, early metal enrichment, and cosmic reionization. In this first ASPIRE paper, we report the discovery of a filamentary structure traced by the luminous quasar J0305-3150 and ten [OIII] emitters at z=6.6. This structure has a 3D galaxy overdensity of δgal=12.6 over 637 cMpc3, one of the most overdense structures known in the early universe, and could eventually evolve into a massive galaxy cluster. Together with existing VLT/MUSE and ALMA observations of this field, our JWST observations reveal that J0305-3150 traces a complex environment where both UV-bright and dusty galaxies are present, and indicate that the early evolution of galaxies around the quasar is not simultaneous. In addition, we discovered 31 [OIII] emitters in this field at other redshifts, 5.310). We use this to estimate the black hole merger rate in AGNs to be about 2.8±1.8\, Gpc−3yr−1, comparable to theoretical expectations. We find that AGNs can explain the rate and mass distribution of the observed events with primary black hole mass in the pair-instability mass gap (M≳50\, M⊙).}, author = {Gayathri, V. and Yang, Y. and Tagawa, H. and Haiman, Zoltán and Bartos, I.}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {American Astronomical Society}, title = {{Black hole mergers of AGN origin in LIGO–Virgo’s O1–O3a observing periods}}, doi = {10.3847/2041-8213/ac2cc1}, volume = {920}, year = {2021}, } @article{17537, abstract = {The recent gravitational wave merger event, GW190521, has challenged our understanding of the stellar-mass black hole (BH) formation. The primary and secondary BH are both inferred to fall inside the pair-instability (PI) mass gap. Here we propose that the formation of such binaries is possible through gas accretion onto the BH remnants of Population III (Pop~III) stars born in high-redshift (z>10) minihalos. Once the parent halo has grown to the atomic-cooling limit, even brief episodes of gas accretion in the dense central regions of the halo can increase the masses of Pop~III remnant BHs above the PI limit. Starting with a BBH with an initial mass of O(100) M⊙ we find that it would only need to spend about 100~Myr in the inner few pc of an atomic-cooling halo to accrete about 50~M⊙ of material and resemble a system similar to GW190521. The dynamical friction timescale for the binary to sink to the dense inner region of its parent halo is comparable or shorter than the accretion timescale required to increase their mass above the PI limit. Once in the core of the halo, the binary can enter a phase of hyper-Eddington accretion, where it would only take a few thousand years to exceed the PI limit through accretion. Even more massive BBHs could form through this channel, and be detectable by detectors with improved low-frequency sensitivity. Single Pop~III BH remnants would also grow through accretion and could later form binaries dynamically. As little as a few percent of Pop~III BH remnants may be sufficient to match the rate of massive BBH mergers inferred from GW190521 of 0.13+0.3−0.11Gpc−3yr−1.}, author = {Safarzadeh, Mohammadtaher and Haiman, Zoltán}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {1}, publisher = {American Astronomical Society}, title = {{Formation of GW190521 via gas accretion onto population III stellar black hole remnants born in high-redshift minihalos}}, doi = {10.3847/2041-8213/abc253}, volume = {903}, year = {2020}, } @article{17605, abstract = {Despite the rapidly growing number of stellar-mass binary black hole mergers discovered through gravitational waves, the origin of these binaries is still not known. In galactic centers, black holes can be brought to each others' proximity by dynamical processes, resulting in mergers. It is also possible that black holes formed in previous mergers encounter new black holes, resulting in so-called hierarchical mergers. Hierarchical events carry signatures such as higher-than-usual black hole mass and spin. Here we show that the recently reported gravitational-wave candidate, GW170817A, could be the result of such a hierarchical merger. In particular, its chirp mass ∼40 M⊙ and effective spin of χeff ∼ 0.5 are the typically expected values from hierarchical mergers within the disks of active galactic nuclei. We find that the reconstructed parameters of GW170817A strongly favor a hierarchical merger origin over having been produced by an isolated binary origin (with an odds ratio of > 10^3).}, author = {Gayathri, V. and Bartos, I. and Haiman, Zoltán and Klimenko, S. and Kocsis, B. and Márka, S. and Yang, Y.}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {American Astronomical Society}, title = {{GW170817A as a hierarchical black hole merger}}, doi = {10.3847/2041-8213/ab745d}, volume = {890}, year = {2020}, } @article{17607, abstract = {The heaviest neutron stars and lightest black holes expected to be produced by stellar evolution leave the mass-range 2.2 M⊙≲m≲5 M⊙ largely unpopulated. Objects found in this so-called lower mass gap likely originate from a distinct astrophysical process. Such an object, with mass 2.6 M⊙ was recently detected in the binary merger GW190814 through gravitational waves by LIGO/Virgo. Here we show that black holes in the mass gap are naturally assembled through mergers and accretion in AGN disks, and can subsequently participate in additional mergers. We compute the properties of AGN-assisted mergers involving neutron stars and black holes, accounting for accretion. We find that mergers in which one of the objects is in the lower mass gap represent up to 4% of AGN-assisted mergers detectable by LIGO/Virgo. The lighter object of GW190814, with mass 2.6 M⊙, could have grown in an AGN disk through accretion. We find that the unexpectedly high total mass of 3.4 M⊙ observed in the neutron star merger GW190425 may also be due to accretion in an AGN disk.}, author = {Yang, Y. and Gayathri, V. and Bartos, I. and Haiman, Zoltán and Safarzadeh, M. and Tagawa, H.}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {American Astronomical Society}, title = {{Black hole formation in the lower mass gap through mergers and accretion in AGN disks}}, doi = {10.3847/2041-8213/abb940}, volume = {901}, year = {2020}, } @article{17627, abstract = {Observations of high-redshift quasars indicate that supermassive black holes (SMBHs) with masses greater than ∼109 M⊙ were assembled within the first billion years after the Big Bang. It is unclear how such massive black holes (BHs) formed so early. One possible explanation is that these SMBHs were seeded by "heavy" direct collapse black holes (DCBHs) with masses of MBH ≈ 105 M⊙, 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 BH mass to halo mass ratios that are much higher than expected for BH remnants of Population III (Pop III) stars that have grown to the same mass (∼106 M⊙). We also show that when Tvir ≈ 104 K halos (the potential sites of DCBH formation) merge with much larger nearby halos (Mh > 1010 M⊙), 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 BH seeds due to the unusually high BH mass to stellar mass ratios of the faintest observed quasars, with inferred BH masses below ∼106 M⊙.}, author = {Visbal, Eli and Haiman, Zoltán}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {1}, publisher = {American Astronomical Society}, title = {{Identifying direct collapse black hole seeds through their small host galaxies}}, doi = {10.3847/2041-8213/aadf3a}, volume = {865}, year = {2018}, } @article{17640, abstract = {Gravitational waves (GWs) in the nano-hertz band are great tools for understanding the cosmological evolution of supermassive black holes (SMBHs) in galactic nuclei. We consider SMBH binaries in high-z ultra-luminous infrared galaxies (ULIRGs) as sources of a stochastic GW background (GWB). ULIRGs are likely associated with gas-rich galaxy mergers containing SMBHs that possibly occur at most once in the life of galaxies, unlike multiple dry mergers at low redshift. Adopting a well-established sample of ULIRGs, we study the properties of the GWB due to coalescing binary SMBHs in these galaxies. Since the ULIRG population peaks at z>1.5, the amplitude of the GWB is not affected even if BH mergers are delayed by as long as ∼ 10 Gyrs. Despite the rarity of the high-z ULIRGs, we find a tension with the upper limits from Pulsar Timing Array (PTA) experiments. This result suggests that if a fraction fm,gal of ULIRGs are associated with SMBH binaries, then no more than 20fm,gal(λEdd/0.3)5/3(tlife/30 Myr) % of the binary SMBHs in ULIRGs can merge within a Hubble time, for plausible values of the Eddington ratio of ULIRGs (λEdd) and their lifetime (tlife).}, author = {Inayoshi, Kohei and Ichikawa, Kohei and Haiman, Zoltán}, issn = {2041-8205}, journal = {The Astrophysical Journal Letters}, number = {2}, publisher = {American Astronomical Society}, title = {{Gravitational waves from supermassive black hole binaries in ultraluminous infrared galaxies}}, doi = {10.3847/2041-8213/aad8ad}, volume = {863}, year = {2018}, } @article{17617, abstract = {Most standard descriptions of Type II migration state that massive, gap-opening planets must migrate at the viscous drift rate. This is based on the idea that the disk is separated into an inner and outer region and gas is considered unable to cross the gap. In fact, gas easily crosses the gap on horseshoe orbits, nullifying this necessary premise which would set the migration rate. In this work, it is demonstrated using highly accurate numerical calculations that the actual migration rate is dependent on disk and planet parameters, and can be significantly larger or smaller than the viscous drift rate. In the limiting case of a disk much more massive than the secondary, the migration rate saturates to a constant that is sensitive to disk parameters and is not necessarily of the order of the viscous rate. In the opposite limit of a low-mass disk, the migration rate decreases linearly with disk mass. Steady-state solutions in the low disk mass limit show no pile-up outside the secondary's orbit, and no corresponding drainage of the inner disk.}, author = {Duffell, Paul C. and Haiman, Zoltán and MacFadyen, Andrew I. and D'Orazio, Daniel J. and Farris, Brian D.}, issn = {2041-8213}, journal = {The Astrophysical Journal}, number = {1}, publisher = {American Astronomical Society}, title = {{The migration of gap-opening planets is not locked to viscous disk evolution}}, doi = {10.1088/2041-8205/792/1/l10}, volume = {792}, year = {2014}, }