J/ApJ/899/140 632 Gaia Ultracompact Dwarf galaxy candidates (Voggel+, 2020)
A Gaia-based catalog of candidate stripped nuclei and luminous globular clusters
in the halo of Centaurus A.
Voggel K.T., Seth A.C., Sand D.J., Hughes A., Strader J., Crnojevic D.,
Caldwell N.
<Astrophys. J., 899, 140 (2020)>
=2020ApJ...899..140V 2020ApJ...899..140V
ADC_Keywords: Clusters, globular; Galaxies; Optical; Photometry; Colors
Keywords: Globular star clusters ; Elliptical galaxies ;
Ultracompact dwarf galaxies ; Galaxy kinematics ; Star clusters ;
Galaxy nuclei
Abstract:
Tidally stripped galaxy nuclei and luminous globular clusters (GCs)
are important tracers of the halos and assembly histories of nearby
galaxies, but are difficult to reliably identify with typical
ground-based imaging data. In this paper we present a new method to
find these massive star clusters using Gaia DR2, focusing on the
massive elliptical galaxy Centaurus A (Cen A). We show that stripped
nuclei and GCs are partially resolved by Gaia at the distance of Cen A,
showing characteristic astrometric and photometric signatures. We use
this selection method to produce a list of 632 new candidate luminous
clusters in the halo of Cen A out to a projected radius of 150kpc.
Adding in broadband photometry and visual examination improves the
accuracy of our classification. In a spectroscopic pilot program we
have confirmed five new luminous clusters, which includes the 7th and
10th most luminous GC in Cen A. Three of the newly discovered GCs are
further away from Cen A than all previously known GCs. Several of
these are compelling candidates for stripped nuclei. We show that our
novel Gaia selection method retains at least partial utility out to
distances of ∼25Mpc and hence is a powerful tool for finding and
studying star clusters in the sparse outskirts of galaxies in the
local universe.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 83 632 List of Gaia ultra compact dwarf (UCD) candidates
table3.dat 75 14 List of MIKE spectroscopic targets of Gaia-based
UCD candidates
table4.dat 54 57 List of the 57 previously confirmed UCDs that were
used to assess completeness in Figure 1
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJS/150/367 : Globular clusters in NGC 5128 (Peng+, 2004)
J/AJ/132/2187 : MCT1 photometry of NGC 5128 globular clusters (Harris+, 2006)
J/AJ/134/494 : NGC5128 globular clusters UBVRICMT1 phot. & RV (Woodley+,2007)
J/MNRAS/386/1443 : 2dF study of globular clusters in NGC 5128 (Beasley+, 2008)
J/A+A/523/A48 : Gaia photometry (Jordi+, 2010)
J/AJ/139/1871 : Kinematics of globulars in NGC 5128 (Woodley+, 2010)
J/ApJ/708/1335 : Spectroscopy of globulars in NGC 5128 (Woodley+, 2010)
J/AJ/142/199 : Sizes and luminosities of stellar systems (Brodie+, 2011)
J/AJ/143/84 : New candidate globular clusters in NGC 5128 (Harris+, 2012)
J/ApJ/760/87 : Globular clusters of M60 with HST (Strader+, 2012)
J/AJ/145/101 : Updated nearby galaxy catalog (Karachentsev+, 2013)
J/MNRAS/445/2385 : HST/ACS Coma Cluster Survey. X. (den Brok+, 2014)
J/MNRAS/441/3570 : Nuclear star clusters 228 spiral galaxies (Georgiev+, 2014)
J/MNRAS/443/1151 : AIMSS Project. I. Compact Stellar Systems (Norris+, 2014)
J/ApJ/812/34 : Properties UCD candidates in M87/M49/M60 regions (Liu+, 2015)
J/MNRAS/457/2122 : Nuclear star clusters photometric masses (Georgiev+, 2016)
J/A+A/586/A102 : UCDs in the halo of NGC1399 (Voggel+, 2016)
J/MNRAS/469/3444 : Survey Centaurus A's Baryonic Structures II. (Taylor+, 2017)
J/ApJ/858/102 : Gemini/NIFS and HST obs. of the galaxy M59-UCD3 (Ahn+, 2018)
J/ApJ/878/18 : NGVS. XXIII. Nuclear star clusters (Sanchez-Janssen+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- KV19 KV19 sequential identifier
10- 22 F13.9 deg RAdeg [198/205] Right Ascension (J2000)
24- 37 F14.10 deg DEdeg [-46/-40] Declination (J2000)
39- 43 F5.2 --- AEN [0.26/15.42] Gaia DR2 Astrometric Excess Noise
45- 49 F5.2 mag Gmag [11.23/19.0] Gaia DR2 Gmag
51- 54 F4.2 --- BP-RP [1.4/4.97] Gaia DR2 BP/RP Excess Factor
56- 59 F4.2 mag u-r [0.41/3.41]? u-r color (1)
61- 65 F5.2 mag r-z [-0.55/0.91]? r-z color (1)
67- 71 F5.2 mag rmag [14.23/18.21]? r band magnitude (1)
73- 76 F4.2 --- Votes [1/5]? final visual assessment score
78- 81 F4.2 --- CL [0/5.08]? Cluster Likelihood
83- 83 A1 --- Rank Rank
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Note (1): Colors and magnitudes from Taylor+, 2017, J/MNRAS/469/3444
if available, and are all extinction corrected.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 1 A1 --- Label New confirmed UCD labels
3- 10 A8 --- KV19 KV19 sequential identifier
12- 22 F11.7 deg RAdeg [199/204] Right Ascension (J2000)
24- 34 F11.7 deg DEdeg [-46/-41] Declination (J2000)
36- 40 F5.2 mag gmag [15.18/18.3] apparent g band magnitude
42- 47 F6.2 mag gMAG [-10.32/-9.61]? absolute g band magnitude
49- 53 F5.1 km/s RVel [-95.2/719.2] Radial Velocity
55- 58 F4.1 km/s e_RVel [1.2/32.7] Uncertainty in RVel
60- 63 F4.1 --- S/N [5.2/23] Signal to noise
65- 70 F6.4 --- CL [0.0001/5.08]? Cluster Likelihood
72- 75 F4.2 --- Votes [1/3.75]? final visual assessment score
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Taylor+, 2017, J/MNRAS/469/3444 designation
10- 19 F10.6 deg RAdeg [200/202] Right Ascension (J2000)
21- 30 F10.6 deg DEdeg [-44/-42] Declination (J2000)
32- 36 F5.2 mag Gmag [17.39/19.54] Gaia DR2 G band magnitude
38- 43 F6.3 --- AEN [1.76/15.29] Gaia DR2 Astrometric Excess Noise
45- 48 F4.2 --- BP-RP [1.78/3.1] Gaia DR2 BP/RP Excess Factor
50- 54 F5.2 mag gmag [17.02/18.77] g' band mag from Taylor+
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 21-Oct-2021