Overmassive black holes in the $M_{\mathrm{BH}}-\sigma$ diagram do not belong to over (dry) merged galaxies

Abstract

Semi-analytical models in a $\Lambda$CDM cosmology have predicted the presence of outlying, "overmassive" black holes at the high-mass end of the (black hole mass -- galaxy velocity dispersion) $M_{\mathrm{BH}}-\sigma$ diagram (which we update here with a sample of 89 galaxies). They are a consequence of having experienced more dry mergers -- thought not to increase a galaxy's velocity dispersion -- than the "main-sequence" population. Wet mergers and gas-rich processes, on the other hand, preserve the main correlation. Due to the scouring action of binary supermassive black holes, the extent of these dry mergers (since the last significant wet merger) can be traced by the ratio between the central stellar mass deficit and the black hole mass ($M_{\mathrm{def},\ast }/M_{\mathrm{BH}}$). However, in a sample of 23 galaxies with partially depleted cores, including central cluster galaxies, we show that the "overmassive" black holes are actually hosted by galaxies that appear to have undergone the lowest degree of such merging. In addition, the rotational kinematics of 37 galaxies in the $M_{\mathrm{BH}}-\sigma$ diagram reveals that fast and slow rotators are not significantly offset from each other, also contrary to what is expected if these two populations were the product of wet and dry mergers respectively. The observations are thus not in accordance with model predictions and further investigation is required.

8 pages, 4 figures. Accepted for publication in MNRAS

References in corpus (19)

• A Compact Supermassive Binary Black Hole System
• How special are Brightest Group and Cluster Galaxies?
• How Mergers May Affect The Mass Scaling Relations Between Black Holes, Galaxies, and Other Gravitationally Bound Systems
• Ejection of Supermassive Black Holes from Galaxy Cores
• The black hole mass -- stellar velocity dispersion correlation: bulges versus pseudobulges
• The luminosities, sizes and velocity dispersions of Brightest Cluster Galaxies: Implications for formation history
• An Over-Massive Black Hole in the Compact Lenticular Galaxy NGC1277
• Massive binary black holes in galactic nuclei and their path to coalescence
• Gravitational Wave Recoil and the Retention of Intermediate Mass Black Holes
• Unravelling the mystery of the M31 bar
• Dynamics of galaxy cores and supermassive black holes
• Unveiling the Boxy Bulge and Bar of the Andromeda Spiral Galaxy
• The importance of dry and wet merging on the formation and evolution of elliptical galaxies
• A Displaced Supermassive Black Hole in M87
• Photometric Properties and Scaling Relations of Early Type Brightest Cluster Galaxies
• Distribution of Slow and Fast Rotators in the Fornax Cluster
• The Black Hole Mass and Extreme Orbital Structure in NGC1399
• Star formation and figure rotation in the early-type galaxy NGC2974
• A Search for the Most Massive Galaxies. III. Global and Central Structure

Cited by in corpus (21)

• Correlation Between the Total Gravitating Mass of Groups and Clusters and the Supermassive Black Hole Mass of Brightest Galaxies
• Six new supermassive black hole mass determinations from adaptive-optics assisted SINFONI observations
• The most massive black holes on the Fundamental Plane of Black Hole Accretion
• Correlations between supermassive black holes and hot gas atmospheres in IllustrisTNG and X-ray observations
• Two channels of supermassive black hole growth as seen on the galaxies mass-size plane
• Novel calibrations of virial black hole mass estimators in active galaxies based on X-ray luminosity and optical/NIR emission lines
• On the relation between the mass of Compact Massive Objects and their host galaxies
• Disky elliptical galaxies and the allegedly over-massive black hole in the compact massive `ES' galaxy NGC 1271
• Detection of faint broad emission lines in type 2 AGN: III. On the $M_{BH}-{\sigma }_{\star }$ relation of type 2 AGN
• Ultramassive black holes in the most massive galaxies: $M_{\mathrm{BH}}-\sigma$ versus $M_{\mathrm{BH}}-R_{\mathrm{b}}$
• SDSS J0159 as an outlier in the Mbh-sigma space: further clues to support a central tidal disruption event?
• The (Black Hole Mass)-(Spheroid Stellar Density) Relations: $M_{\mathrm{BH}}$--$\mu$ (and $M_{\mathrm{BH}}$--$\Sigma$) and $M_{\mathrm{BH}}$--$\rho$
• Quashing a suspected selection bias in galaxy samples having dynamically-measured supermassive black holes
• Too big to be real? No depleted core in Holm 15A
• SDSS J1058+5443: A blue quasar does not have optical/NUV broad emission lines
• A SysTematic seaRch fOr Dual Agns in meRgINg Galaxies (ASTRO-DARING) II: first results from long-slit spectroscopic observations
• Long-term variability of the composite galaxy SDSS J103911-000057: A candidate of true Type-2 AGN
• On the scaling relations of bulges and early-type galaxies
• Study of Central Intensity Ratio of Seyfert Galaxies in nearby Universe
• The impact of black hole feedback on the UV luminosity and stellar mass assembly of high-redshift galaxies
• The most massive galaxies with large depleted cores: structural parameter relations and black hole masses