J/A+A/645/A92 Dwarf spheroidal galaxies in CenA group (Mueller+, 2021)
The properties of dwarf spheroidal galaxies in the Cen A group:
Stellar populations, internal dynamics, and a heart-shaped Hα ring.
Mueller O., Fahrion K., Rejkuba M., Hilker M., Lelli F., Lutz K.,
Pawlowski M.S., Coccato L., Anand G.S., Jerjen H.
<Astron. Astrophys. 645, A92 (2021)>
=2021A&A...645A..92M 2021A&A...645A..92M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies
Keywords: galaxies: dwarf - galaxies: kinematics and dynamics -
galaxies: stellar content - Galaxy: abundances
Abstract:
Dwarf spheroidal galaxies (dSphs) have been extensively investigated
in the Local Group, but their low luminosity and surface brightness
make similar work in more distant galaxy groups challenging. Modern
instrumentation unlocks the possibility of scrutinizing these faint
systems in other environments, expanding the parameter space of group
properties. We use MUSE spectroscopy to study the properties of 14
known or suspected dSph satellites of Cen A. Twelve targets are
confirmed to be group members based on their radial velocities. Two
targets are background galaxies at ∼50Mpc: KK 198 is a face-on spiral
galaxy, and dw1315-45 is an ultra-diffuse galaxy with an effective
radius of ∼2300pc. The 12 confirmed dSph members of the Cen A group
have old and metal-poor stellar populations and follow the stellar
metallicity-luminosity relation defined by the dwarf galaxies in the
Local Group. In the three brightest dwarf galaxies (KK 197, KKs 55,
and KKs 58), we identify globular clusters, as well as a planetary
nebula in KK197, although its association with this galaxy and/or the
extended halo of Cen A is uncertain. Using four discrete tracers, we
measure the velocity dispersion and dynamical mass of KK197. This dSph
appears dark matter dominated and lies on the radial acceleration
relation of star-forming galaxies within the uncertainties. It also is
consistent with predictions stemming from modified Newtonian dynamics
(MOND). Surprisingly, in the dwarf KK203 we find an extended H ring.
Careful examination of Hubble Space Telescope photometry reveals a
very low level of star formation at ages between 30-300Myr. The
Hα emission is most likely linked to a ∼40Myr old supernova
remnant, although other possibilities for its origin cannot be
entirely ruled out.
Description:
The data were acquired with the MUSE integral field spectrograph
mounted at UT4 of the VLT on Cerro Paranal, Chile as part of a 46 hour
program (PI: Mueller, proposal ID: 0101.A-0193) designed to measure
distances (requiring 26h with FORS2) and line-of-sight velocities (20h
with MUSE) of dwarf galaxy candidates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 107 16 Observation summary for the 14 dwarf galaxy
candidates
list.dat 116 14 List of fits datacubes
fits/* . 14 Individual fits datacubes
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name
12- 13 I2 h RAh Center of observation right ascension (J2000)
15- 16 I2 min RAm Center of observation right ascension (J2000)
18- 21 F4.1 s RAs Center of observation right ascension (J2000)
23 A1 --- DE- Center of observation declination sign (J2000)
24- 25 I2 deg DEd Center of observation declination (J2000)
27- 28 I2 arcmin DEm Center of observation declination (J2000)
30- 31 I2 arcsec DEs Center of observation declination (J2000)
33- 46 A14 --- Date Observing date
48 I1 --- Nexp Number of exposures
50- 53 I4 s Exptime Integration time per exposure
55- 58 F4.2 --- AM Average airmass during observation
60- 62 F3.1 arcsec IQ Average image quality (seeing)
64- 67 F4.1 --- S/N ?=- Measured signal-to-noise ratio on the stacked
cube between 6600 and 6800Å (see text)
69-107 A39 --- Note Note
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name
12- 20 F9.5 deg RAdeg Right Ascension of center (J2000)
21- 29 F9.5 deg DEdeg Declination of center (J2000)
31- 33 F3.1 arcsec/pix scale Scale of the image
35- 37 I3 --- Nx Number of pixels along X-axis
39- 41 I3 --- Ny Number of pixels along Y-axis
43- 46 I4 --- Nz Number of slices
48- 54 F7.2 0.1nm bAWAV Lower value of AWAV interval
56- 62 F7.2 0.1nm BAWAV Upper value of AWAV interval
64- 67 F4.2 0.1nm dAWAV AWAV resolution
69- 75 I7 Kibyte size Size of FITS file
77- 95 A19 --- FileName Name of FITS file, in subdirectory fits
97-116 A20 --- Title Title of the FITS file
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Acknowledgements:
Oliver Mueller, oliver.muller(at)astro.unistra.fr
(End) Patricia Vannier [CDS] 15-Jan-2021