X-Ray Properties of Intermediate-Mass Black Holes in Active Galaxies. Ii. X-Ray-Bright Accretion and Possible Evidence for Slim Disks

Desroches, Louis-Benoit; Greene, Jenny E.; Ho, Luis C.

doi:10.1088/0004-637x/698/2/1515

Cited by 64 publications

(86 citation statements)

References 59 publications

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“…First, they appear to have a very-low incidence of jet activity 63 . Second, we see indirect evidence that they have hotter accretion disks than their more massive cousins [64][65][66] , as expected from basic disk models 67 . As the accretion disk gets hotter, its impact on the surrounding gas will grow.…”

Section: Properties Of Low-mass Black Holessupporting

confidence: 57%

Low-mass black holes as the remnants of primordial black hole formation

2012

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Bridging the gap between the approximately ten solar mass 'stellar mass' black holes and the 'supermassive' black holes of millions to billions of solar masses are the elusive 'intermediatemass' black holes. Their discovery is key to understanding whether supermassive black holes can grow from stellar-mass black holes or whether a more exotic process accelerated their growth soon after the Big Bang. Currently, tentative evidence suggests that the progenitors of supermassive black holes were formed as B10 4 -10 5 M } black holes via the direct collapse of gas. Ongoing searches for intermediate-mass black holes at galaxy centres will help shed light on this formation mechanism.O ver the last decade we have come to understand that supermassive black holes, with masses of millions to billions of times the mass of the Sun, are very common in the centres of massive galaxies 1 . We would like to understand when and how they formed and grew.We cannot yet watch the first supermassive black holes form. They did so soon after the Big Bang, and light from those distant events is beyond the reach of today's telescopes. However, we do have two very interesting limits on the formation of the first black holes. The first comes from observations of the most distant known black holes: light is emitted by material falling into the deep gravitational potential of the black hole. These monsters are so bright that they must be powered by at least billion solar mass black holes. They had very little time to grow, as we see them only a few hundred million years after the Big Bang 2,3 . Whatever process formed and grew the first supermassive black holes had to be very efficient.At the other extreme, we can study the lowest-mass black holes in galaxy nuclei near to us, the left-over seeds that for some reason never grew to be a billion suns. As we describe below, conditions were best to make supermassive black hole seeds soon after the Big Bang. Therefore, black holes found in small galaxies today, with black hole masses of B10 4 -10 6 M } , likely formed early and have not grown significantly since. These black holes have masses between those of 'stellar-mass' black holes that form as the end-product of the life of a massive star and supermassive black holes. We will refer to black holes in this mass range as 'low-mass' black holes, as they are at the low-mass end of supermassive black holes. If we assume that black holes form in a similar way in all galaxies, then the numbers and masses of black holes in small galaxies today contain clues about the formation of the first black holes 4 . The sheer number of left-overs will indicate how commonly black hole seeds were formed, as well as inform future gravitational wave experiments that expect to see a large number of paired low-mass black holes as they spiral together and coalesce 5 . Studying the energy output from low-mass black holes could tell us whether growing black holes at early times were important in shaping early star formation in the galaxies around them 6 .

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Section: Properties Of Low-mass Black Holessupporting

confidence: 57%

Low-mass black holes as the remnants of primordial black hole formation

2012

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“…By contrast, previous X-ray studies of low-mass AGNs indicate that α ox is, on average, larger than in high-mass AGNs (e.g., Greene & Ho 2007a;Miniutti et al 2009;Desroches et al 2009;Dong et al 2012a), falling systematically below the lowluminosity extension of the α ox −L ν (2500 Å) relation of Steffen et al (2006). The previous samples span a wide range in α ox , from ≈−1.7 to −1.…”

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confidence: 58%

Um 625 Revisited: Multiwavelength Study of a Seyfert 1 Galaxy With a Low-Mass Black Hole

Jiang

Dong

et al. 2013

ApJ

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UM 625, previously identified as a narrow-line active galactic nucleus (AGN), actually exhibits broad Hα and Hβ lines whose width and luminosity indicate a low black hole (BH) mass of 1.6 × 10 6 M . We present a detailed multiwavelength study of the nuclear and host galaxy properties of UM 625. Analysis of Chandra and XMM-Newton observations suggests that this system contains a heavily absorbed and intrinsically X-ray weak (α ox = −1.72) nucleus. Although not strong enough to qualify as radio loud, UM 625 does belong to a minority of low-mass AGNs detected in the radio. The broadband spectral energy distribution constrains the bolometric luminosity to L bol ≈ (0.5-3) × 10 43 erg s −1 and L bol /L Edd ≈ 0.02-0.15. A comprehensive analysis of Sloan Digital Sky Survey and Hubble Space Telescope images shows that UM 625 is a nearly face-on S0 galaxy with a prominent, relatively blue pseudobulge (Sérsic index n = 1.60) that accounts for ∼60% of the total light in the R band. The extended disk is featureless, but the central ∼150-400 pc contains a conspicuous semi-ring of bright, blue star-forming knots, whose integrated ultraviolet luminosity suggests a star formation rate of ∼0.3 M yr −1 . The mass of the central BH roughly agrees with the value predicted from its bulge velocity dispersion but is significantly lower than that expected from its bulge luminosity.

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“…To reinforce the AGN origin of the emission lines, we repeat the analysis but using only those objects in our sample with detected nuclear X-ray emission as a sig-nature of AGN activity (39 out of 127 dwarf galaxies; e.g. Desroches et al 2009;Dong et al 2012). The results we obtain are consistent with those found for the full sample of 127 objects.…”

Section: Resultsmentioning

confidence: 99%

Exploring the Limits of AGN Feedback: Black Holes and the Star Formation Histories of Low-mass Galaxies

Martín-Navarro

Mezcua

2018

ApJL

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Energy feedback, either from active galactic nuclei (AGN) or from supernovae, is required to understand galaxy formation within a Λ-Cold Dark Matter cosmology. We study a sample of 127 low-mass galaxies, comparing their stellar populations properties to the mass of the central supermassive black hole, in order to investigate the effect of AGN feedback. We find a loose coupling between star formation history and black hole mass, which seems to suggest that AGN activity does not dominate baryonic cooling in low-mass galaxies. We also find that a break in the M • -σ relation marks a transitional stellar mass, M trans = 3.4 ± 2.1 × 10 10 M ⊙ , remarkably similar to M ⋆ . Our results are in agreement with a bi-modal star formation process where the AGN-dominated feedback of high-mass galaxies transitions towards a supernovae-driven regime in low-mass systems, as suggested by numerical simulations.

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X-Ray Properties of Intermediate-Mass Black Holes in Active Galaxies. Ii. X-Ray-Bright Accretion and Possible Evidence for Slim Disks

Cited by 64 publications

References 59 publications

Low-mass black holes as the remnants of primordial black hole formation

Low-mass black holes as the remnants of primordial black hole formation

Um 625 Revisited: Multiwavelength Study of a Seyfert 1 Galaxy With a Low-Mass Black Hole

Exploring the Limits of AGN Feedback: Black Holes and the Star Formation Histories of Low-mass Galaxies

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