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J/ApJ/850/15 Mass-to-light ratios in low-mass early-type gal. (Pechetti+, 2017)

Detection of enhanced central mass-to-light ratios in low-mass early-type galaxies: evidence for black holes? Pechetti R., Seth A., Cappellari M., McDermid R., den Brok M., Mieske S., Strader J. <Astrophys. J., 850, 15 (2017)> =2017ApJ...850...15P
ADC_Keywords: Galaxies, nearby; Velocity dispersion; Stars, masses; Black holes Keywords: galaxies: elliptical and lenticular, cD ; galaxies: formation ; galaxies: kinematics and dynamics ; quasars: supermassive black holes Abstract: We present dynamical measurements of the central mass-to-light ratio (M/L) of a sample of 27 low-mass early-type ATLAS3D galaxies. We consider all ATLAS3D galaxies with 9.7<log(M*/M)<10.5 in our analysis, selecting out galaxies with available high-resolution Hubble Space Telescope (HST) data, and eliminating galaxies with significant central color gradients or obvious dust features. We use the HST images to derive mass models for these galaxies and combine these with the central velocity dispersion values from ATLAS3D data to obtain a central dynamical M/L estimate. These central dynamical M/Ls are higher than dynamical M/Ls derived at larger radii and stellar population estimates of the galaxy centers in ∼80% of galaxies, with a median enhancement of ∼14% and a statistical significance of 3.3σ. We show that the enhancement in the central M/L is best described either by the presence of black holes in these galaxies or by radial initial mass function variations. Assuming a black hole model, we derive black hole masses for the sample of galaxies. In two galaxies, NGC 4458 and NGC 4660, the data suggest significantly overmassive black holes, while in most others only upper limits are obtained. We also show that the level of M/L enhancements we see in these early-type galaxy nuclei are consistent with the larger enhancements seen in ultracompact dwarf galaxies (UCDs), supporting the scenario where massive UCDs are created by stripping galaxies of these masses. Description: In this study, we combine central velocity dispersion values of the galaxies from the ATLAS3D survey (Cappellari+ 2011, J/MNRAS/413/813), with high-resolution mass models derived from HST images to obtain the central M/Ls of these galaxies. We use the optical integral field spectroscopic observations for the ATLAS3D galaxies taken from SAURON Integral Field Unit (IFU) on the William Herschel Telescope (WHT). We downloaded the HST imaging using the Hubble Legacy Archive, including imaging from the Wide Field and Planetary Camera 2 (WFPC2), Advanced Camera for Survey (ACS)/Wide Field Channel (WFC), ACS/High Resolution Camera (HRC), and Wide Field Camera 3 (WFC3)/ultraviolet and visible light (UVIS). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 35 237 Multi-Gaussian Expansion (MGE) parameters of all 27 galaxies table2.dat 84 27 Mass-to-light ratios, central velocity dispersions and HST imaging data of all 27 galaxies table3.dat 105 27 Black hole masses, sphere of influence, ATLAS3D and HST pixel sizes of all 27 galaxies
See also: B/hst : HST Archived Exposures Catalog (STScI, 2007) VII/237 : HYPERLEDA. I. Catalog of galaxies (Paturel+, 2003) J/ApJ/621/673 : Line indices for 124 early-type galaxies (Thomas+, 2005) J/ApJS/182/216 : Surface photometry of Virgo ellipticals (Kormendy+, 2009) J/ApJ/714/25 : AMUSE-Virgo survey. II. (Gallo+, 2010) J/MNRAS/413/813 : ATLAS3D project. I. (Cappellari+, 2011) J/MNRAS/443/1151 : AIMSS Project. I. Compact Stellar Systems (Norris+, 2014) J/ApJ/798/54 : "Under-massive" black hole candidates (Graham+, 2015) J/ApJ/826/L32 : Black hole masses in megamaser disk galaxies (Greene+, 2016) J/MNRAS/458/2221 : ATLAS3D Project. XXXI (Nyland+, 2016) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 9 A9 --- Name Galaxy's name from LEDA, Paturel+ (2003, VII/237) 11- 15 A5 --- Filt Filter in which the MGE components are derived (F475W, F606W, F702W, F814W) 17- 22 F6.3 [Lsun/pc2] log(I) [-0.3/6] Surface brightness of each Gaussian 24- 29 F6.3 [arcsec] log(Sig) [-1.8/1.7] Width of each Gaussian 31- 35 F5.3 --- q [0.1/1] Axis ratio of each Gaussian
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 9 A9 --- Name Galaxy's name from LEDA, Paturel+ (2003, VII/237) 11- 15 F5.2 Msun/Lsun M/L-c [1.3/11.2] Central M/L derived using JAM models (1) 17- 21 F5.2 Msun/Lsun b_M/L-c [0.9/10.2] Lower bound on M/L-cen (1) 23- 27 F5.2 Msun/Lsun B_M/L-c [1.7/12.1] Upper bound on M/L-cen (1) 29- 33 F5.2 Msun/Lsun M/L-dyn [0.9/10.5] Dynamical M/L derived from outer parts of galaxies (2) 35 I1 --- q_M/L-dyn [0/3]? Quality flag for M/L-dyn (3=good) (3) 37- 40 F4.2 Msun/Lsun M/L-pop [1.3/4.3] Stellar population M/L derived from nuclear spectra (4) 42- 47 F6.2 km/s Sigma-c [49.8/317.1] Central velocity dispersions 49- 53 F5.2 km/s e_Sigma-c [2/10.6] Uncertainty in σ-c 55 I1 --- r_Sigma-c [1/2] Source for σ-c (5) 57- 65 A9 --- Camera HST camera used for mass models 67- 71 A5 --- Filt1 Filter used for mass models (F475W, F606W, F702W, F814W) 73- 84 A12 --- Filt2 Filters used for colors
Note (1): Central M/L derived using Jeans Anisotropic Models (JAM) models (Cappellari+, 2008MNRAS.390...71C). All the values are in SDSS r-band. The Low and High values include the errors from velocity dispersions and 2.5% systematic error. Note (2): Dynamical M/L derived by dynamically fitting the outer regions of the galaxy (>2", within 1 Re). We assume an error of 6% on all of these M/L as given in Cappellari+ (2013MNRAS.432.1862C). Note (3): Quality flag for M/L-dyn as follows: 0 = low-quality JAM fit due to barred galaxies, dust or uncertain deprojection due to a low inclination of the galaxy. 3 = a good JAM fit to the data. Note (4): Stellar population M/L derived by fitting the ATLAS3D central spectrum of a galaxy assuming a Kroupa IMF. We assume an error of 6% on all of these M/L as given in Cappellari+ (2013MNRAS.432.1862C). Note (5): Central velocity dispersions derived from reference as follows: 1 = ATLAS3D kinematic data; 2 = van den Bosch+ (1998MNRAS.293..343V).
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 9 A9 --- Name Galaxy's name from LEDA, Paturel+ (2003, VII/237) 11- 15 F5.3 km/s sigma-e [1.7/2.4] Effective stellar velocity dispersion (6) 17- 22 F6.3 [Msun] logM* [9.8/10.6] Galaxy mass, log, Cappellari+ (2013MNRAS.432.1709C) 24- 31 E8.2 Msun MBH-dyn [0/778000000] Best-fit BH masses using (M/L)-dyn (7) 33- 40 E8.2 Msun b_MBH-dyn [0/557000000] Lower bound on MBH-dyn (7) 42- 49 E8.2 Msun B_MBH-dyn [26400000/998000000] Upper bound on MBH-dyn (7) 51- 58 E8.2 Msun MBH-pop [0/1290000000] Best-fit BH masses using (M/L)-pop (8) 60- 67 E8.2 Msun b_MBH-pop [0/1070000000] Lower bound on MBH-pop (8) 69- 76 E8.2 Msun B_MBH-pop [14600000/1510000000] Upper bound on MBH-pop (8) 78- 85 E8.2 Msun MBH-pre [173000/545000000] Expected BH masses from MBH-σ (9) 87- 92 F6.2 pc rSOI [7.2/263.7] Sphere of Influence predicted using MBH-dyn (10) 94- 99 F6.2 pc Pixel1 [50/187] Pixel size, ATLAS-3D (11) 101-105 F5.2 pc Pixel2 [2.6/11.1] Pixel size, HST (12)
Note (6): Effective stellar velocity dispersion adopted from Cappellari+ (2013MNRAS.432.1709C). They were calculated by co-adding all SAURON spectra within an effective ellipse of area πRe2, where Re is the effective radius. Note (7): Best-fit BH masses derived using (M/L)-dyn as the true stellar M/L in our JAM models. Note (8): Best-fit BH masses derived using (M/L)-pop as the true stellar M/L in our JAM models. Note (9): Expected BH masses from the MBH-σ relationship from Equation∼2. Galaxies NGC4458 and NGC4660 are highly significant detections. Note (10): Sphere of influence calculated from the derived BH masses (MBH-dyn) using rSOI=G*MBH/σ-e2. Note (11): Pixel size of ATLAS^3D kinematic data for our sample of galaxies that were derived using the distances from Cappellari+ (2011, J/MNRAS/413/813). Note (12): Pixel size of HST images for our sample of galaxies that were derived using the distances from Cappellari+ (2011, J/MNRAS/413/813).
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Jun-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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