J/ApJ/723/251 Keck/LRIS confirmation of Coma membership (Chiboucas+, 2010)
Keck/LRIS spectroscopic confirmation of Coma cluster dwarf galaxy membership
assignments.
Chiboucas K., Tully R.B., Marzke R.O., Trentham N., Ferguson H.C.,
Hammer D., Carter D., Khosroshahi H.
<Astrophys. J., 723, 251-266 (2010)>
=2010ApJ...723..251C 2010ApJ...723..251C
ADC_Keywords: Clusters, galaxy ; Galaxies, photometry ; Photometry, HST ;
Redshifts ; Spectroscopy ; Morphology
Keywords: galaxies: clusters: individual (Coma) - galaxies: dwarf
Abstract:
Keck/LRIS multi-object spectroscopy has been carried out on 140 of
some of the lowest and highest surface brightness faint (19<R<22)
dwarf galaxy candidates in the core region of the Coma Cluster. These
spectra are used to measure redshifts and establish membership for
these faint dwarf populations. The primary goal of the low surface
brightness sample is to test our ability to use morphological and
surface brightness criteria to distinguish between Coma Cluster
members and background galaxies using high resolution Hubble Space
Telescope/Advanced Camera for Surveys images. Candidates were rated as
expected members, uncertain, or expected background. From 93 spectra,
51 dwarf galaxy members and 20 background galaxies are identified. Our
morphological membership estimation success rate is ∼100% for objects
expected to be members and better than ∼90% for galaxies expected to
be in the background. We confirm that low surface brightness is a very
good indicator of cluster membership. High surface brightness galaxies
are almost always background with confusion arising only from the
cases of the rare compact elliptical (cE) galaxies. The more
problematic cases occur at intermediate surface brightness. Many of
these galaxies are given uncertain membership ratings, and these were
found to be members about half of the time. In a sample of 47 high
surface brightness, ultracompact dwarf candidates, 19 objects have
redshifts which place them in the Coma Cluster, while another 6 have
questionable redshift measurements but may also prove to be members.
Description:
We use the Keck LRIS low resolution imaging spectrometer in
multi-object spectroscopy mode. A dichroic was used to split light at
5600Å between red and blue detectors. We observed four masks over
two nights 2008 April 2 and 3 (resolution of ∼200km/s).
This work is part of the Hubble Space Telescope/Advanced Camera for
Surveys (HST/ACS) Coma Cluster Treasury Survey (Carter et al.
2008ApJS..176..424C 2008ApJS..176..424C), a two-passband imaging survey originally
designed to cover 740arcmin2 in the Coma Cluster to a depth of
IC∼26.6 for point sources and µe,I<26.0mag/arcsec2 for
extended sources. Over 200arcmin2 have been completed.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 120 101 LRIS (membership test sample) redshift results
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See also:
VII/42 : GMP catalogue: galaxies in the Coma cluster (Godwin+ 1983)
J/MNRAS/411/2439 : Coma Treasury Survey. Structural parameters (Hoyos+, 2011)
J/MNRAS/404/1745 : Dwarf galaxies in Coma supercluster (Mahajan+, 2010)
J/MNRAS/392/1265 : Faint galaxies in Coma cluster spectroscopy (Smith+, 2009)
J/ApJS/175/462 : Spectroscopy of Coma early-type galaxies (Corsini+, 2008)
J/ApJS/169/225 : Photometry in the Coma cluster (Eisenhardt+, 2007)
J/A+A/451/1159 : BVRI imaging of the Coma cluster (Adami+, 2006)
J/A+A/459/679 : RB photometry of LSBG in Coma (Adami+, 2006)
J/ApJ/602/664 : Morphology of galaxies in Coma cluster (Gutierrez+, 2004)
J/A+A/395/753 : Spectroscopy of Coma galaxies. II. (Wegner+, 2002)
J/AJ/121/2331 : SDSS redshifts in the Coma cluster (Castander+, 2001)
J/ApJS/137/279 : Spectroscopic Survey in Coma (Mobasher+, 2001)
J/A+A/296/643 : LSB galaxies in Coma (Karachentsev+ 1995)
J/A+AS/111/265 : Velocities in Coma cluster (Biviano+ 1995)
J/ApJS/97/77 : Catalog of Coma Cluster Galaxies (Doi+ 1995)
J/MNRAS/243/390 : Galaxy redshift survey in a Coma (Karachentsev+ 1990)
http://astronomy.swin.edu.au/coma : Coma Cluster Treasury Survey homepage
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- S Status (Mm, Bg, Un, PM, or PB) (1)
4- 10 I7 --- ID [10162/4042826] Identification number
11 A1 --- f_ID [he] Note on the observation (2)
13 I1 --- PT ?=x [1/5] Membership probability defined by
N.T. on HST/ACS image (3)
15 I1 --- PF ?=x [1/4] Membership probability defined by
H.F. on HST/ACS image (3)
17- 21 F5.2 mag Rmag [18.68/23.41]? R-band magnitude (4)
22 A1 --- f_Rmag [f] Blended photometry (2)
24- 28 F5.2 mag F814Wc ? HST/ACS F814W magnitude; corrected (5)
30- 34 F5.2 mag F814W ? HST/ACS F814W magnitude (5)
36- 39 F4.2 mag B-V ? (B-V) color index (3" aperture) (4)
40 A1 --- f_B-V [f] Blended photometry (2)
42- 46 F5.2 mag g-I ? (F475W-F814W) color index (2.25" aperture)
48- 52 F5.2 mag/arcsec2 mu0 ? Central surface brightness (µ0(R))
54- 58 F5.2 mag/arcsec2 mue ? Mean effective surface brightness
(<µe,F814W>)
60- 61 I2 h RAh [12/13] Hour of right ascension (J2000)
63- 64 I2 min RAm Minute of right ascension (J2000)
66- 70 F5.2 s RAs Second of right ascension (J2000)
72 A1 --- DE- [+] Sign of declination (J2000)
73- 74 I2 deg DEd [27/28] Degree of declination (J2000)
76- 77 I2 arcmin DEm Arcminute of declination (J2000)
79- 83 F5.2 arcsec DEs Arcsecond of declination (J2000)
85- 90 I6 km/s czA ? Absorption redshift
92- 94 I3 km/s e_czA ? czA uncertainty (6)
96- 99 F4.1 aW/m2/nm Rfx ? Relative flux (in 10-16erg/s/cm2/Å)
101-106 I6 km/s czE ? Emission redshift
107 A1 --- f_czE [g] redshift from red-side (2)
109-111 I3 km/s e_czE ? czE uncertainty
113-116 F4.1 --- S/N [3.7/61.1]? Signal to noise ratio per
Angstrom around 5000Å
118-120 A3 --- MType Morphological type
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Note (1): Membership status as follows:
Mm = Member
Bg = Background
Un = Uncertain
PM = Possible member (failed)
PB = Possible background (failed)
Note (2): Flag as follows:
e = Object was observed in a separate run in 2009.
f = Photometry is for two blended components including the UCD target and
another source centered 0.9 arcsec west of it.
g = Redshift measurement from red-side data.
h = Object was observed in two masks.
Note (3): Membership probability classes of the authors (N.Trenton and
H.Ferguson) as follows:
1 = expected member
2 = probable member
3 = possible member
4 = expected background
5 = the galaxy was an extra object that landed in the slit
x = no membership probability assigned
See section 2.1.1 for further explanations.
Note (4): BVR photometry from catalog of Adami et al. (2006,
Cat. J/A+A/451/1159).
Note (5): F814W photometry comes from SExtractor measurements from our ACS data
(Hammer et al. 2010ApJS..191..143H 2010ApJS..191..143H).
Note (6): Errors include contributions from the cross-correlation measurement
uncertainty and from the uncertainties in the sky line wavelength
calibration shift.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 13-Jul-2012