J/ApJ/858/102 Gemini/NIFS and HST obs. of the galaxy M59-UCD3 (Ahn+, 2018)
The black hole in the most massive ultracompact dwarf galaxy M59-UCD3.
Ahn C.P., Seth A.C., Cappellari M., Krajnovic D., Strader J., Voggel K.T.,
Walsh J.L., Bahramian A., Baumgardt H., Brodie J., Chilingarian I.,
Chomiuk L., den Brok M., Frank M., Hilker M., McDermid R.M., Mieske S.,
Neumayer N., Nguyen D.D., Pechetti R., Romanowsky A.J., Spitler L.
<Astrophys. J., 858, 102 (2018)>
=2018ApJ...858..102A 2018ApJ...858..102A
ADC_Keywords: Galaxies, spectra; Spectra, infrared; Velocity dispersion
Keywords: galaxies: clusters: general ; galaxies: dwarf ; galaxies: evolution ;
galaxies: formation ; galaxies: kinematics and dynamics
Abstract:
We examine the internal properties of the most massive ultracompact
dwarf galaxy (UCD), M59-UCD3, by combining adaptive-optics-assisted
near-IR integral field spectroscopy from Gemini/NIFS and Hubble Space
Telescope (HST) imaging. We use the multiband HST imaging to create a
mass model that suggests and accounts for the presence of multiple
stellar populations and structural components. We combine these mass
models with kinematics measurements from Gemini/NIFS to find a
best-fit stellar mass-to-light ratio (M/L) and black hole (BH) mass
using Jeans anisotropic models (JAMs), axisymmetric Schwarzschild
models, and triaxial Schwarzschild models. The best-fit parameters in
the JAM and axisymmetric Schwarzschild models have BHs between 2.5 and
5.9 million solar masses. The triaxial Schwarzschild models point
toward a similar BH mass but show a minimum χ2 at a BH mass of
∼0. Models with a BH in all three techniques provide better fits to
the central Vrms profiles, and thus we estimate the BH mass to be
4.2-1.7+2.1x106M☉ (estimated 1σ uncertainties). We
also present deep radio imaging of M59-UCD3 and two other UCDs in
Virgo with dynamical BH mass measurements, and we compare these to
X-ray measurements to check for consistency with the fundamental plane
of BH accretion. We detect faint radio emission in M59cO but find only
upper limits for M60-UCD1 and M59-UCD3 despite X-ray detections in
both these sources. The BH mass and nuclear light profile of M59-UCD3
suggest that it is the tidally stripped remnant of a
∼109-1010M☉ galaxy.
Description:
We obtained images of M59-UCD3 from the HST GO Cycle 23 program 14067
(PI: Ahn) with the Wide Field Camera 3 (WFC3) instrument, which has a
pixel scale of 0.04/pix. Our data were taken through the F475W and
F814W filters. The exposure times in each filter were 1470 and 747s
for F475W and F814W, respectively.
Our spectroscopic data were obtained with the Near-infrared Integral
Field Spectrometer (NIFS) mounted on the Gemini North telescope using
Altair laser guide star adaptive optics. The observations were taken
on the nights of 2015 May 4, 5, and 6 in the K band at wavelengths
from 2.0 to 2.4um. Gemini/NIFS data are taken in 0.1"x0.04 pixels over
a 3" field of view with a spectral resolution of R∼5700
(σinst=22km/s).
We obtained deep radio continuum data for M59 and M60 with the Karl G.
Jansky Very Large Array (VLA) as part of program 15A-091 (PI: Strader)
in 2015 February and March.
Three ultracompact dwarf dwarf galaxies (UCDs; M59-UCD3, M59cO, and
M60-UCD1) are shown in Figure 12. These UCDs have been studied in the
X-rays using Chandra by several previous authors (Luo+ 2013,
J/ApJS/204/14 ; Strader+ 2013ApJ...775L...6S 2013ApJ...775L...6S ; Hou & Li
2016ApJ...819..164H 2016ApJ...819..164H ; Pandya+ 2016, J/ApJ/819/162), but we revisit
this analysis to ensure consistency. All our results are consistent
with these past studies.
There are two separate observations of M59 (encompassing both M59-UCD3
and M59cO; obsID 2068 and 8074) and six observations of M60 (in 2000,
2007 and 2011) that cover M60-UCD1. We downloaded these observations
from the Chandra data archive.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
12 42 11.04 +11 38 41.2 M59-UCD3 = [SVR2015] M59-UCD3
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 83 109 Gemini/NIFS kinematic measurements
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Description of file: goodbinv2sn25_bin.fits (available on the FTP) is a
FITS file image containing the location of each bin for the measured
kinematics file (for mapping from the "Bin" column in Table 3 to
spatial location in the data cube).
See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
J/A+AS/134/75 : Central Fornax Cluster. II. Galaxy spectrosc. (Hilker+ 1999)
J/A+A/383/823 : Radial velocities of UCOs in Fornax (Mieske+, 2002)
J/ApJ/655/144 : ACS Virgo Cluster Survey. XIII. (Mei+, 2007)
J/ApJS/182/216 : Surface photometry of Virgo ellipticals (Kormendy+, 2009)
J/ApJ/725/670 : Kinematics in the M32 nucleus (Seth, 2010)
J/AJ/142/199 : Sizes and luminosities of stellar systems (Brodie+, 2011)
J/MNRAS/414/3699 : Study of hot stellar systems and galaxies (Misgeld+, 2011)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/ApJS/204/14 : Deep Chandra observations of NGC 4649. I. (Luo+, 2013)
J/A+A/570/A2 : Spectra and RVs of nuclear stars (Feldmeier+, 2014)
J/MNRAS/443/1151 : AIMSS Project. I. Compact Stellar Systems (Norris+, 2014)
J/AJ/149/53 : RVs of 12 Milky Way globular clusters (Kimmig+, 2015)
J/ApJ/813/82 : z<0.06 broad-line AGN emission-line measures (Reines+, 2015)
J/MNRAS/457/2122 : Nuclear star clusters photometric masses (Georgiev+, 2016)
J/ApJ/826/L32 : Black hole masses in megamaser disk galaxies (Greene+, 2016)
J/ApJ/819/162 : Chandra obs. of UCDs (Pandya+, 2016)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Bin [0/108] Bin number associated with
goodbinv2sn25_bin.fits file
5- 11 F7.3 pix Xpix [-13.7/13.7] Distance from center
in x direction
13- 19 F7.3 pix Ypix [-15.1/15.1] Distance from center
in y direction
21- 23 I3 --- Npix [1/131] Number of pixels in that bin
25- 29 F5.3 --- Chi2 [0.2/3] Reduced Chi2 value
31- 37 F7.3 km/s Vel [412/479] Measured radial velocity
39- 43 F5.3 km/s e_Vel [2/8] Uncertainty in the measured velocity
45- 50 F6.3 km/s sigma [50/84] Measured velocity dispersion
52- 57 F6.3 km/s e_sigma [2/12] Uncertainty in the velocity dispersion
59- 64 F6.3 --- h3 [-0.11/0.11] Measured skewness
66- 70 F5.3 --- e_h3 [0.02/0.09] Uncertainty in skewness
72- 77 F6.3 --- h4 [-0.2/0.1] Measured kurtosis
79- 83 F5.3 --- e_h4 [0.02/0.2] Uncertainty in kurtosis
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Apr-2019