Updated Mass Scaling Relations for Nuclear Star Clusters and a Comparison to Supermassive Black Holes

Scott, Nicholas; Graham, Alister W.

doi:10.1088/0004-637x/763/2/76

Cited by 109 publications

(116 citation statements)

References 67 publications

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“…In this model, the number densities of very luminous quasars are preserved, while those of lower-luminosity quasars gradually decrease, in better agreement with the data. Evidence for a break in the black hole-galaxy scaling relations is also now claimed in the local universe (Scott & Graham 2013) and by independent theoretical models (Cirasuolo et al 2005;Fontanot et al 2006Fontanot et al , 2015. Biases in the local samples of dynamically measured black holes may, however, seriously limit our true knowledge of the intrinsic scaling relations between black holes and their host galaxies (e.g., Shankar et al 2016 and references therein).…”

Section: Comparison With Merger Modelsmentioning

confidence: 88%

THE CHANDRA COSMOS-LEGACY SURVEY: THE z > 3 SAMPLE

Marchesi

Civano

Salvato

et al. 2016

ApJ

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We present the largest high-redshift (3 < z < 6.85) sample of X-ray-selected active galactic nuclei (AGNs) on a contiguous field, using sources detected in the Chandra COSMOS-Legacy survey. The sample contains 174 sources, 87 with spectroscopic redshift and the other 87 with photometric redshift (z phot ). In this work, we treat z phot as a probability-weighted sum of contributions, adding to our sample the contribution of sources with z phot <3 but z phot probability distribution >0 at z>3. We compute the number counts in the observed 0.5-2 keV band, finding a decline in the number of sources at z>3 and constraining phenomenological models of the X-ray background. We compute the AGN space density at z>3 in two different luminosity bins. At higher luminosities (logL(2-10 keV) > 44.1 erg s −1 ), the space density declines exponentially, dropping by a factor of ∼20 from z∼3 to z∼6. The observed decline is ∼80% steeper at lower luminosities (43.55 erg s −1 < logL(2-10 keV)<44.1 erg s) from z∼3 to z∼4.5. We study the space density evolution dividing our sample into optically classified Type 1 and Type 2 AGNs. At logL (2-10 keV)>44.1 erg s −1, unobscured and obscured objects may have different evolution with redshift, with the obscured component being three times higher at z∼5. Finally, we compare our space density with predictions of quasar activation merger models, whose calibration is based on optically luminous AGNs. These models significantly overpredict the number of expected AGNs at logL (2-10 keV)>44.1 erg s −1 with respect to our data.

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Section: Comparison With Merger Modelsmentioning

confidence: 88%

THE CHANDRA COSMOS-LEGACY SURVEY: THE z > 3 SAMPLE

Marchesi

Civano

Salvato

et al. 2016

ApJ

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“…We can estimate the progenitor mass assuming that these UCDs follow the same scaling relations between BH mass and bulge or galaxy mass as unstripped galaxies (e.g., Kormendy & Ho 2013;van den Bosch 2016), as well as similar scaling relations for NSCs (e.g., Scott & Graham 2013;Georgiev et al 2016). Mieske et al (2013) used BH scaling relations to show that today's UCDs are consistent with typically having ∼1% of the luminosity of their progenitor galaxy, suggesting progenitor galaxies for VUCD3 and M59cO of roughly M 10 9…”

Section: Discussionmentioning

confidence: 99%

Detection of Supermassive Black Holes in Two Virgo Ultracompact Dwarf Galaxies

Ahn

Seth

Brok

et al. 2017

ApJ

101

129

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We present the detection of supermassive black holes (BHs) in two Virgo ultracompact dwarf galaxies (UCDs), VUCD3 and M59cO. We use adaptive optics assisted data from the Gemini/NIFS instrument to derive radial velocity dispersion profiles for both objects. Mass models for the two UCDs are created using multi-band Hubble Space Telescope imaging, including the modeling of mild color gradients seen in both objects. We then find a bestfit stellar mass-to-light ratio (M/L) and BH mass by combining the kinematic data and the deprojected stellar mass profile using Jeans Anisotropic Models. Assuming axisymmetric isotropic Jeans models, we detect BHs in both objects with masses of 4.4 Comparing these values with nuclear star clusters shows that, while it is possible that these UCDs are highly radially anisotropic, it seems unlikely. These detections constitute the second and third UCDs known to host supermassive BHs. They both have a high fraction of their total mass in their BH; ∼13% for VUCD3 and ∼18% for M59cO. They also have low best-fit stellar M/Ls, supporting the proposed scenario that most massive UCDs host high-mass fraction BHs. The properties of the BHs and UCDs are consistent with both objects being the tidally stripped remnants of 10 M 9  galaxies.

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“…The nuclear regions of galaxies are of special interest for galaxy formation and evolution studies because of the scaling correlations between the mass of the nuclear star cluster and other galaxy properties, such as the galaxy mass (e.g. Wehner & Harris 2006;Rossa et al 2006;Ferrarese et al 2006;Scott & Graham 2013).…”

Section: Introductionmentioning

confidence: 99%

KMOS view of the Galactic centre

Feldmeier-Krause

Neumayer

Schödel

et al. 2015

A&A

106

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Context. The Galactic centre hosts a crowded, dense nuclear star cluster with a half-light radius of 4 pc. Most of the stars in the Galactic centre are cool late-type stars, but there are also > ∼ 100 hot early-type stars in the central parsec of the Milky Way. These stars are only 3−8 Myr old. Aims. Our knowledge of the number and distribution of early-type stars in the Galactic centre is incomplete. Only a few spectroscopic observations have been made beyond a projected distance of 0.5 pc of the Galactic centre. The distribution and kinematics of earlytype stars are essential to understand the formation and growth of the nuclear star cluster. Methods. We cover the central >4 pc 2 (0.75 sq. arcmin) of the Galactic centre using the integral-field spectrograph KMOS (VLT). We extracted more than 1000 spectra from individual stars and identified early-type stars based on their spectra. Results. Our data set contains 114 bright early-type stars: 6 have narrow emission lines, 23 are Wolf-Rayet stars, 9 stars have featureless spectra, and 76 are O/B type stars. Our wide-field spectroscopic data confirm that the distribution of young stars is compact, with 90% of the young stars identified within 0.5 pc of the nucleus. We identify 24 new O/B stars primarily at large radii. We estimate photometric masses of the O/B stars and show that the total mass in the young population is > ∼ 12 000 M . The O/B stars all appear to be bound to the Milky Way nuclear star cluster, while less than 30% belong to the clockwise rotating disk. We add one new star to the sample of stars affiliated with this disk. Conclusions. The central concentration of the early-type stars is a strong argument that they have formed in situ. An alternative scenario, in which the stars formed outside the Galactic centre in a cluster that migrated to the centre, is refuted. A large part of the young O/B stars is not on the disk, which either means that the early-type stars did not all form on the same disk or that the disk is dissolving rapidly.

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Updated Mass Scaling Relations for Nuclear Star Clusters and a Comparison to Supermassive Black Holes

Cited by 109 publications

References 67 publications

THE CHANDRA COSMOS-LEGACY SURVEY: THE z > 3 SAMPLE

THE CHANDRA COSMOS-LEGACY SURVEY: THE z > 3 SAMPLE

Detection of Supermassive Black Holes in Two Virgo Ultracompact Dwarf Galaxies

KMOS view of the Galactic centre

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