The Most Massive Galaxies with Large Depleted Cores: Structural Parameter Relations and Black Hole Masses
Abstract
Luminous spheroids (M V ≲ -21.50 ± 0.75 mag) contain partially depleted cores with sizes (R b) typically 0.02-0.5 kpc. However, galaxies with R b > 0.5 kpc are rare and poorly understood. Here, we perform detailed decompositions of the composite surface brightness profiles, extracted from archival Hubble Space Telescope and ground-based images, of 12 extremely luminous “large-core” galaxies that have R b > 0.5 kpc and M V ≲ -23.50 ± 0.10 mag, fitting a core-Sérsic model to the galaxy spheroids. Using 28 “normal-core” (i.e., R b < 0.5 kpc) galaxies and one “large-core” (i.e., R b > 0.5 kpc) galaxy from the literature, we constructed a final sample of 41 core-Sérsic galaxies. We find that large-core spheroids (with stellar masses M * ≳ 1012 M ⊙) are not simple high-mass extensions of the less luminous normal-core spheroids having M * ∼ 8 × 1010-1012 M ⊙. While the two types follow the same strong relations between the spheroid luminosity L V and R b ({R}{{b}}\propto {L}V1.38+/- 0.13), and the spheroid half-light radius R e ({R}{{e}}\propto {L}V1.08+/- 0.09, for ellipticals plus Brightest Cluster Galaxies), we discover a break in the core-Sérsic σ-L V relation occurring at M V ∼ -23.50 ± 0.10 mag. Furthermore, we find a strong log-linear R b-M BH relation for the 11 galaxies in the sample with directly determined supermassive black hole (SMBH) masses M BH—3/11 galaxies are large-core galaxies—such that {R}{{b}}\propto {M}BH}0.83+/- 0.10. However, for the large-core galaxies the SMBH masses estimated from the M BH-σ and core-Sérsic M BH-L relations are undermassive, by up to a factor of 40, relative to expectations from their large R b values, confirming earlier results. Our findings suggest that large-core galaxies harbor overmassive SMBHs (M BH ≳ 1010 M ⊙), considerably (∼3.7-15.6σ and ∼0.6-1.7σ) larger than expectations from the spheroid σ and L, respectively. We suggest that the R b-M BH relation can be used to estimate SMBH masses in the most massive galaxies.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2019
- DOI:
- 10.3847/1538-4357/ab4d4f
- arXiv:
- arXiv:1910.10240
- Bibcode:
- 2019ApJ...886...80D
- Keywords:
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- Supermassive black holes;
- cD galaxies;
- Elliptical galaxies;
- Lenticular galaxies;
- Galaxy photometry;
- Galaxy nuclei;
- Galaxy structure;
- 1663;
- 209;
- 456;
- 915;
- 611;
- 609;
- 622;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 24 pages, 14 figures (some with low quality due to arXiv file size limitations), accepted (2019, October 14) for publication in ApJ, v2: surname/forename tagged correctly