J/ApJ/914/16 NGC 5128 GCs from PISCes, Gaia DR2 and NSC (Hughes+, 2021)
NGC 5128 globular cluster candidates out to 150kpc: a comprehensive catalog
from Gaia and ground-based data.
Hughes A.K., Sand D.J., Seth A., Strader J., Voggel K., Dumont A.,
Crnojevic D., Caldwell N., Forbes D.A., Simon J.D., Guhathakurta P.,
Toloba E.
<Astrophys. J., 914, 16 (2021)>
=2021ApJ...914...16H 2021ApJ...914...16H
ADC_Keywords: Clusters, globular; Galaxies, nearby; Photometry, ugriz;
Colors; Proper motions; Radial velocities
Keywords: Globular star clusters ; Optical identification ; Galaxy evolution
Abstract:
We present a new catalog of 40502 globular cluster (GC) candidates in
NGC5128 out to a projected radius of ∼150kpc based on data from the
Panoramic Imaging Survey of Centaurus and Sculptor, the Gaia Data
Release 2, and the NOAO Source Catalog. Ranking these candidates based
on the likelihood that they are true GCs, we find that approximately
1900 belong to our top two ranking categories and should be the
highest priority for spectroscopic follow-up for confirmation. Taking
into account our new data and a vetting of previous GC catalogs, we
estimate a total GC population of 1450±160 GCs. We show that a
substantial number of sources previously argued to be low-velocity GCs
are instead foreground stars, reducing the inferred GC velocity
dispersion. This work showcases the power of Gaia to identify slightly
extended sources at the ∼4Mpc distance of NGC 5128, enabling accurate
identification of GCs throughout the entire extended halo, not just
the inner regions that have been the focus of most previous work.
Description:
The foundational data set of our globular cluster (GC) search is deep
NGC 5128 Magellan/Megacam imaging from the Panoramic Imaging Survey of
Centaurus and Sculptor (PISCeS) survey. The PISCeS produced a
wide-field resolved stellar map of NGC 5128 out to a projected
galactocentric radius of ∼150kpc (Crnojevic+ 2016ApJ...823...19C 2016ApJ...823...19C).
We explain our use of Gaia DR2 to identify NGC 5128 GCs in Section 4.4.
The NOAO Source Catalog (NSC) is a unified collection of nearly all of
the public data taken on the Dark Energy Camera (DECam) on the Blanco
4m telescope at CTIO, as well as the Mosaic3 imager on the 4m Mayall
telescope at KPNO. See Section 2.3.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
13 25 27.61 -43 01 08.8 NGC 5128 = NAME Centaurus A
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 307 40502 Catalog of globular cluster candidates in NGC5128
table2.dat 454 474916 Catalog of all PISCeS sources in NGC 5128
table4.dat 109 557 Confirmed globular clusters (GCs) around Cen A
table5.dat 144 50 Foreground stars that were previously
misclassified as GCs
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Description of file:
datafile1.fits.gz & datafile2.fits.gz, in the FTP section, are the
Table 1 and Table 2 in FITS format as downloaded from the paper.
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/ApJ/449/592 : NGC 5128 PN. III. (Hui+ 1995)
J/AJ/128/723 : Washington Photometry in NGC 5128. II (Harris+, 2004)
J/ApJS/150/367 : Globular clusters in NGC 5128 (Peng+, 2004)
J/AJ/130/873 : BQS objects in the SDSS DR3 area (Jester+, 2005)
J/A+A/450/105 : Properties of 153 Galactic globular clusters (Bica+, 2006)
J/AJ/132/2187 : MCT1 phot. of NGC 5128 globular clusters (Harris+, 2006)
J/ApJS/171/101 : GCs in the ACS Virgo cluster survey (Jordan+, 2007)
J/AJ/134/494 : NGC 5128 GCs UBVRICMT1 phot. & RV (Woodley+, 2007)
J/MNRAS/386/1443 : 2dF study of globular clusters in NGC 5128 (Beasley+, 2008)
J/MNRAS/396/1075 : GCs in nearby dwarf galaxies. II (Georgiev+, 2009)
J/AJ/140/2101 : NGC 5128 globular clusters photometry (Sinnott+, 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/MNRAS/416/155 : GCs in five early-type galaxies (Faifer+, 2011)
J/AJ/143/84 : New candidate globular clusters in NGC 5128 (Harris+, 2012)
J/ApJ/773/L27 : GCs in ACSVCS early-type galaxies (Park+, 2013)
J/AJ/148/32 : Globular cluster candidates in NGC 3115 (Jennings+, 2014)
J/MNRAS/450/1962 : M60 SLUGGS and Gemini/GMOS combined study (Pota+, 2015)
J/ApJ/805/65 : FLAMES obs. of NGC 5128's globular clusters (Taylor+, 2015)
J/ApJS/227/12 : NGVS XXV. Virgo GCs photometry (Powalka+, 2016)
J/MNRAS/469/3444 : Centaurus A's Baryonic Structures II. (Taylor+, 2017)
J/ApJ/872/202 : CFHT ugi photometry of globular clusters in M85 (Ko+, 2019)
J/ApJ/899/140 : Gaia Ultracompact Dwarf galaxy candidates (Voggel+, 2020)
J/A+A/645/A92 : Dwarf spheroidal galaxies in CenA group (Mueller+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [H21-]
5- 10 I6 --- ID [46/474905] "H21" ID from this work
12- 23 A12 --- Name Discovery ID, if available (DISCOVERY_ID)
25- 34 F10.6 deg RAdeg [196.2/204.5] PISCeS right ascension (J2000)
(RA)
36- 45 F10.6 deg DEdeg [-45.5/-40.8] PISCeS declination (J2000) (DEC)
47- 55 F9.6 mag gmag [0/24.8] PISCeS g-band magnitude (PISCES_GMAG)
57- 60 F4.2 mag e_gmag [0.01/0.8] Uncertainty on the gmag
(PISCESGMAGERR)
62- 70 F9.6 mag rmag [0/24.2] PISCeS r-band magnitude (PISCES_RMAG)
72- 75 F4.2 mag e_rmag [0.01/2.1] Uncertainty on the rmag
(PISCESRMAGERR)
77- 81 F5.2 mag C3-6 [1/31.3] Concentration index value, C3-6;
see Section 4.2 (C36)
83- 85 I3 mag Gmag [999] Gaia DR2 G-band magnitude (always "999")
(GAIA_GMAG)
87- 96 F10.6 mas/yr pmRA [-17.5/15.7]?=999 Gaia DR2 proper motion in RA
direction (pmRA*cosDE) (PM_RA)
98- 107 F10.6 mas/yr e_pmRA [0.1/5.2]?=999 pmRA uncertainty (PMRAERR)
109- 118 F10.6 mas/yr pmDE [-15.4/10.8]?=999 Gaia DR2 proper motion in
decl. direction (PM_DEC)
120- 129 F10.6 mas/yr e_pmDE [0.1/5]?=999 pmDE uncertainty (PMDECERR)
131- 140 F10.6 mas plx [-5.8/7.2]?=999 Gaia DR2 parallax (PARALLAX)
142- 151 F10.6 mas e_plx [0.08/4]?=999 Parallax uncertainty
(PARALLAX_ERR)
153- 162 F10.6 mas Noise [0/20]?=999 Gaia DR2 astrometric excess
noise, see Section 4.4.2 (AEN)
164- 173 F10.6 mag E(BP-RP) [0.6/5]?=999 Gaia DR2 BP/RP excess factor
(BR_EXCESS)
175- 185 F11.6 mag (u-r)0 [-0.84/8.84]?=999 NSC (u-r)0 color index
(UR_COLOR)
187- 196 F10.6 mag (r-z)0 [-5.7/6.1]?=999 NSC (r-z)0 color index
(RZ_COLOR)
198- 205 F8.6 --- LC3-6 [0.84/1] Candidate likelihood based on
C3-6 (CONCENTRATION_LIKELIHOOD)
207- 216 F10.6 --- Lpm [0.0003/1]?=999 Candidate likelihood based on
proper motion (PROPERMOTIONLIKELIHOOD)
218- 227 F10.6 --- Lplx [0.002/1]?=999 Candidate likelihood based on
parallax (PARALLAX_LIKELIHOOD)
229- 238 F10.6 --- LNoise [0.023/1]?=999 Candidate likelihood based on
AEN (AEN_LIKELIHOOD)
240- 249 F10.6 --- LEx [0.023/1]?=999 Candidate likelihood based on
BRexcess (BRE_LIKELIHOOD)
251- 258 F8.4 --- Lcol [0.023/1]?=999 Candidate likelihood based on
NSC color (COLOR_LIKELIHOOD)
260- 268 E9.4 --- TotL [5.8e-11/1] Total likelihood of candidate
being a GC in NGC 5128 (TOTAL_LIKELIHOOD)
270- 275 A6 --- Rank Classification based on data availability in
key data sets (CANDIDATE_RANK)
277 A1 --- Conf [ny] Is it a confirmed GC in NGC 5128?
(CONFIRMED)
279- 307 A29 --- Ref Reference(s) (REFERENCES) (G1)
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [H21-]
5- 10 I6 --- ID [1/474916] A unique "H21" ID which we assign
12- 23 A12 --- Name Discovery ID, if available (DISCOVERY_ID)
25- 34 F10.6 deg RAdeg [196.2/204.5]? PISCeS right ascension (J2000)
(RA)
36- 45 F10.6 deg DEdeg [-45.5/-40.8] PISCeS declination (J2000) (DEC)
47- 55 F9.6 mag gmag [0/28.05] PISCeS g-band magnitude
(PISCES_GMAG)
57- 60 F4.2 mag e_gmag [0.01/3] Uncertainty on the gmag
(PISCESGMAGERR)
62- 70 F9.6 mag rmag [0/25.6] PISCeS r-band magnitude (PISCES_RMAG)
72- 75 F4.2 mag e_rmag [0.01/2.1] Uncertainty on the rmag
(PISCESRMAGERR)
77- 87 F11.6 mag C3-6g [-326/55] PISCeS g-band concentration index
value (GC3_6)
89- 99 F11.6 mag C3-6r [-67/423] PISCeS r-band concentration index
value (RC3_6)
101 A1 --- Band [gr] PISCeS magnitude band used to calculate
concentration_likeliness (BAND_USED)
103- 113 F11.7 deg RAGdeg [196.2/204.5]?=0 Gaia DR2 right ascension
(ICRS) (GAIA_RA)
115- 125 F11.7 deg DEGdeg [-45.5/-40.8]?=0 Gaia DR2 declination (ICRS)
(GAIA_DEC)
127- 129 I3 mag Gmag [999] Gaia G-band magnitude (always "999")
(GAIA_GMAG)
131- 140 F10.6 mas/yr pmRA [-99.2/138.4]?=999 Gaia DR2 proper motion in
RA (PM_RA)
142- 151 F10.6 mas/yr e_pmRA [0.05/5.4]?=999 pmRA uncertainty (PMRAERR)
153- 163 F11.6 mas/yr pmDE [-159.61/86.7]?=999 Gaia DR2 proper motion
in decl. (PM_DEC)
165- 174 F10.6 mas/yr e_pmDE [0.05/5.2]?=999 pmDE uncertainty (PMDECERR)
176- 185 F10.6 mas plx [-23.7/29.3]?=999 Gaia DR2 parallax (PARALLAX)
187- 196 F10.6 mas e_plx [0.03/4.1]?=999 Parallax uncertainty
(PARALLAX_ERR)
198- 207 F10.6 --- Noise [0/20]?=999 Gaia DR2 astrometric excess
noise, see Section 4.4.2 (AEN)
209- 218 F10.6 mag E(BP-RP) [0.2/5]?=999 Gaia DR2 BP/RP excess factor
(BR_EXCESS)
220- 228 F9.6 mag umagNSC [13.88/24.43]?=0 NSC u-band magnitude
(NSC_UMAG)
230- 237 F8.6 mag e_umagNSC [0.003/0.3]?=0 umagNSC uncertainty
(NSCUMAGERR)
239- 247 F9.6 mag gmagNSC [18/22]?=0 NSC g-band magnitude (NSC_GMAG)
249- 256 F8.6 mag e_gmagNSC [0.0008/0.3]?=0 gmagNSC uncertainty
(NSCGMAGERR)
258- 266 F9.6 mag rmagNSC [14.1/22.4]?=0 NSC r-band magnitude
(NSC_RMAG)
268- 275 F8.6 mag e_rmagNSC [0.0002/0.3]?=0 rmagNSC uncertainty
(NSCRMAGERR)
277- 285 F9.6 mag imagNSC [13.6/22.8]?=0 NSC i-band magnitude
(NSC_IMAG)
287- 294 F8.6 mag e_imagNSC [0.0003/0.3]?=0 imagNSC uncertainty
(NSCIMAGERR)
296- 304 F9.6 mag zmagNSC [12.6/22.9]?=0 NSC z-band magnitude
(NSC_ZMAG)
306- 313 F8.6 mag e_zmagNSC [0.0007/0.3]?=0 zmagNSC uncertainty
(NSCZMAGERR)
315- 324 F10.6 mag (u-r)0 [-77.2/81]?=999 NSC (u-r)0 color index
(UR_COLOR)
326- 335 F10.6 mag (r-z)0 [-79.4/81.6]?=999 NSC (r-z)0 color index
(RZ_COLOR)
337- 344 F8.6 --- LC3-6 [0/1] Candidate likelihood based on C3-6
(CONCENTRATION_LIKELIHOOD)
346- 353 F8.6 --- Check [0/1] Galaxy/blend check (STRUCTURE_CHECK)
355- 364 F10.6 --- Lpm [0/1]?=999 Candidate likelihood based on
proper motion (PROPERMOTIONLIKELIHOOD)
366- 375 F10.6 --- Lplx [0/1]?=999 Candidate likelihood based on
parallax (PARALLAX_LIKELIHOOD)
377- 386 F10.6 --- LNoise [0.023/1]?=999 Candidate likelihood based on
AEN (AEN_LIKELIHOOD)
388- 397 F10.6 --- LEx [0.023/1]?=999 Candidate likelihood based on
BRexcess (BRE_LIKELIHOOD)
399- 406 F8.4 --- Lcol [-1/1]?=999 Candidate likelihood based on NSC
color (COLOR_LIKELIHOOD)
408- 415 F8.6 --- TotL [0/1] Total likelihood of candidate being a
GC in NGC 5128 (TOTAL_LIKELIHOOD)
417- 422 A6 --- Rank Classification based on data availability in
key data sets; see Section 3 (CANDIDATE_RANK)
424 A1 --- Conf [ny] Is it a confirmed GC in NGC 5128?
(CONFIRMED)
426- 454 A29 --- Ref Reference (s) (REFERENCES) (G1)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [H21-]
5- 10 I6 --- ID [69900/345370]? "H21" ID from this work
12- 22 A11 --- Name Discovery ID, if available (1)
24- 54 A31 --- Ref References (G1)
56- 65 F10.6 deg RAdeg [199.5/202.5] Right Ascension (J2000)
67- 76 F10.6 deg DEdeg [-44.2/-42.3] Declination (J2000)
78- 83 F6.2 arcmin Rad [0.95/103.8] Radial distance
85- 89 F5.2 mag gmag [17.47/22.74]? PISCeS g-band mag
91- 95 F5.2 mag rmag [16.86/21.98]? PISCeS r-band mag
97-100 I4 km/s RVel [146/1051]? Radial velocity
102-104 I3 km/s e_RVel [1/256]? Radial velocity error
106-107 A2 --- r_RVel Radial velocity reference (G1)
109-109 A1 --- Notes Notes (2)
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Note (1): For completeness, if a GC is not in PISCeS or is within the 10'
from the center of NGC 5128, we still include it in this catalog using
its most recent astrometry and without PISCeS photometry (ID is blank).
Note (2): Notes as follows:
1 = GC is in our fiducial sample (see Section 3);
2 = The position of GC pff-gc-028 is originally listed in
Peng+ (2004, J/ApJS/150/367) in HMS coordinates as
13:25:01.16-42:56:51.05.
In their Table 1, Woodley+ (2007, J/AJ/134/494) gives the position of
this GC as 13:20:01.16-42:56:51.05, which due to an unfortunate
change in one digit of right ascension minutes, points to an empty
patch of sky.
3 = The position of C01/GC0005 is listed in Taylor+ (2010ApJ...712.1191T 2010ApJ...712.1191T)
as 200.93333-43.187083, which is 2.65" away from the position
indicated by all other studies that noted this GC.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
12- 21 F10.6 deg DEdeg Declination in decimal degrees (J2000)
23- 25 I3 km/s RVel [28/594] Radial velocity
27- 29 I3 km/s e_RVel [9/232] RVel uncertainty
31 A1 --- r_RVel Reference on RVel
33- 38 F6.2 mas/yr pmRA [-50.3/8.28] Gaia DR2 proper motion in RA
40- 43 F4.2 mas/yr e_pmRA [0.15/3.23] pmRA uncertainty
45- 50 F6.2 mas/yr pmDE [-14/2.3] Gaia DR2 proper motion in decl.
52- 55 F4.2 mas/yr e_pmDE [0.13/4.16] pmDE uncertainty
57- 61 F5.2 mas plx [-2.24/2.26] Gaia DR2 parallax
63- 66 F4.2 mas e_plx [0.07/1.55] plx uncertainty
68- 77 A10 --- Name Discovery ID, if available
79- 87 A9 --- r_Name Reference on Name (G1)
89- 97 A9 --- Name2 Other name
99- 103 A5 --- r_Name2 Reference on Name2 (G1)
105- 112 A8 --- Name3 Other name
114- 120 A7 --- r_Name3 Reference on Name3 (G1)
122- 129 A8 --- Name4 Other name
131 A1 --- r_Name4 Reference on Name4 (G1)
133- 140 A8 --- Name5 Other name
142 A1 --- r_Name5 Reference on Name5 (G1)
144 I1 --- Note [1/2]? Note (1)
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Note (1): Note as follows:
1 = This object was found to be a star based on HST/ACS imaging by
Harris+ (2006, J/AJ/132/2187).
2 = See Appendix C for information about the naming history of this object.
3 = This object was identified as a GC based on HST/ACS imaging by
Harris+ (2006, J/AJ/132/2187). It also has large (σ≥4)
proper-motion and/or parallax measurements in Gaia DR2, and careful
reinspection of its HST imaging confirms it to be a point source.
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Global notes:
Note (G1): References as follows:
a = Graham & Phillips (1980ApJ...239L..97G 1980ApJ...239L..97G);
b = van den Bergh et al. (1981AJ.....86...24V 1981AJ.....86...24V);
c = Hesser et al. (1986ApJ...303L..51H 1986ApJ...303L..51H);
d = Harris et al. (1992AJ....104..613H 1992AJ....104..613H);
e = Holland et al. (1999A&A...348..418H 1999A&A...348..418H);
f = Harris et al. (2002AJ....124.1435H 2002AJ....124.1435H);
g = Peng et al. (2004, J/ApJS/150/367);
h = Martini & Ho (2004ApJ...610..233M 2004ApJ...610..233M);
i = Harris et al. (2004, J/AJ/128/723);
j = Woodley et al. (2005AJ....129.2654W 2005AJ....129.2654W);
k = Gomez et al. (2006A&A...447..877G 2006A&A...447..877G);
l = Harris et al. (2006, J/AJ/132/2187);
m = Rejkuba et al. (2007A&A...469..147R 2007A&A...469..147R);
n = Woodley et al. (2007, J/AJ/134/494);
o = Beasley et al. (2008, J/MNRAS/386/1443);
p = Georgiev et al. (2009, J/MNRAS/396/1075);
q = Mouhcine et al. (2010MNRAS.404.1157M 2010MNRAS.404.1157M);
r = Woodley et al. (2010, J/ApJ/708/1335);
s = Woodley et al. (2010, J/AJ/139/1871);
t = Sinnott et al. (2010, J/AJ/140/2101);
u = Taylor et al. (2010ApJ...712.1191T 2010ApJ...712.1191T);
v = Georgiev et al. (2010MNRAS.406.1967G 2010MNRAS.406.1967G);
w = Harris et al. (2012, J/AJ/143/84);
x = Taylor et al. (2015, J/ApJ/805/65);
y = Taylor et al. (2017, J/MNRAS/469/3444);
z = Voggel et al. (2020, J/ApJ/899/140);
aa = Fahrion et al. (2020A&A...634A..53F 2020A&A...634A..53F);
ab = Muller et al. (2021, J/A+A/645/A92).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Dec-2022