J/ApJ/947/34 New velocity measurements of NGC 5128 GCs (Hughes+, 2023)
New velocity measurements of NGC 5128 globular clusters out to 130 kpc: outer
halo kinematics, substructure, and dynamics.
Hughes A.K., Sand D.J., Seth A., Strader J., Lidman C., Voggel K.,
Dumont A., Crnojevic D., Mateo M., Caldwell N., Forbes D.A., Pearson S.,
Guhathakurta P., Toloba E.
<Astrophys. J., 947, 34 (2023)>
=2023ApJ...947...34H 2023ApJ...947...34H
ADC_Keywords: Clusters, globular; Galaxies, nearby; Radial velocities;
Spectra, optical; Photometry; Colors
Keywords: Globular star clusters ; Radial velocity ; Galaxy stellar halos ;
Galaxy masses ; Catalogs
Abstract:
We present new radial velocity measurements from the Magellan and the
Anglo-Australian Telescopes for 175 previously known and 121 newly
confirmed globular clusters (GCs) around NGC 5128, the nearest
accessible massive early-type galaxy at D=3.8Mpc. Remarkably, 28 of
these newly confirmed GCs are at projected radii >50' (≳54kpc),
extending to ∼130kpc, in the outer halo where few GCs had been
confirmed in previous work. We identify several subsets of GCs that
spatially trace halo substructures that are visible in red giant
branch star maps of the galaxy. In some cases, these subsets of GCs
are kinematically cold, and may be directly associated with and
originate from these specific stellar substructures. From a combined
kinematic sample of 645 GCs, we see evidence for coherent rotation at
all radii, with a higher rotation amplitude for the metal-rich GC
subpopulation. Using the tracer mass estimator, we measure a total
enclosed mass of 2.5±0.3x1012M☉ within ∼120kpc, an estimate
that will be sharpened with forthcoming dynamical modeling. The
combined power of stellar mapping and GC kinematics makes NGC 5128 an
ongoing keystone for understanding galaxy assembly at mass scales
inaccessible in the Local Group.
Description:
We obtained multiobject fiber spectroscopy using the Michigan/Magellan
Fiber System (M2FS) instrument on the Magellan/Clay 6.5m telescope at
the Las Campanas Observatory on several runs between 2017 and 2019.
In the current work, we used the "low" resolution spectrograph
(R∼1300 and wavelength range 4100-6000Å) to measure radial
velocities and confirm the nature of the globular cluster (GC)
candidates from H21 (Hughes+ 2021, J/ApJ/914/16). We focused on radial
velocity measurements using the strong Hβ (4861Å) and magnesium
triplet (Mgb, 5167-5183Å) absorption features.
See Section 2.2.
We obtained additional multiobject fiber spectroscopy using the
2dF/AAOmega instrument (R∼1300 and wavelength range ∼3500-5500Å to
cover the Hβ and Mg b lines) on the Anglo-Australian Telescope
(AAT) 3.9m telescope at the Siding Springs Observatory in Australia in
2017, 2019, and 2022.
See Section 2.3.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
13 25 27.61 -43 01 08.8 NGC 5128 = NAME Cen A
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 103 174 Radial velocity measurements of previously known
globular clusters (GCs) in NGC 5128
table4.dat 75 122 Radial velocity measurements of newly confirmed GCs
in NGC 5128
table5.dat 62 674 Foreground stars and background galaxies in the
vicinity of NGC 5128
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See also:
J/ApJ/449/592 : NGC 5128 PN. III. (Hui+ 1995)
J/A+A/369/812 : UVKs phot. of globular clusters in NGC 5128 (Rejkuba, 2001)
J/ApJ/591/850 : Radial velocities of M49 globular clusters (Cote+, 2003)
J/AJ/128/723 : Washington Photometry in NGC 5128. II (Harris+, 2004)
J/ApJ/600/716 : NGC 5128 Chandra X-ray point sources (Minniti+, 2004)
J/ApJS/150/367 : Globular clusters in NGC 5128 (Peng+, 2004)
J/ApJ/602/685 : NGC 5128 planetary nebulae (Peng+, 2004)
J/AJ/132/2187 : MCT1 phot. of NGC 5128 globular clusters (Harris+, 2006)
J/AJ/133/504 : Gal. around CenA/M83 galaxy complex (Karachentsev+, 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/ApJ/682/199 : Globulars with X-ray sources in NGC 5128 (Woodley+, 2008)
J/MNRAS/396/1075 : Globular cluster in nearby dwarf gal. II (Georgiev+, 2009)
J/A+A/513/A52 : Velocities of NGC 1399 globular clusters (Schuberth+, 2010)
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/AJ/141/61 : Star clusters in M31. II. (Caldwell+, 2011)
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/748/29 : Spectroscopy of M87 globular clusters (Romanowsky+, 2012)
J/A+A/544/A115 : Velocities of NGC 4636 globular clusters (Schuberth+, 2012)
J/AJ/149/53 : RVels of 12 Milky Way globular clusters (Kimmig+, 2015)
J/ApJ/805/65 : FLAMES obs. of NGC 5128's globular clusters (Taylor+, 2015)
J/MNRAS/448/2717 : Bayesian analysis of resolved stellar sp. (Walker+, 2015)
J/ApJ/802/30 : NGVS VI. Ultra-compact dwarfs in M87 (Zhang+, 2015)
J/ApJ/824/42 : Star clusters in M31. VII. GCs RVs (Caldwell+, 2016)
J/AJ/153/114 : GCs in 27 nearby ETGs from the SLUGGS survey (Forbes+, 2017)
J/MNRAS/469/3444 : Centaurus A's Baryonic Structures II. (Taylor+, 2017)
J/ApJ/899/140 : Gaia Ultracompact Dwarf galaxy candidates (Voggel+, 2020)
J/ApJ/914/16 : NGC 5128 GCs from PISCes, Gaia DR2 and NSC (Hughes+, 2021)
J/A+A/645/A92 : Dwarf spheroidal galaxies in CenA group (Mueller+, 2021)
J/A+A/657/A93 : Fornax globular clusters (Chaturvedi+, 2022)
J/ApJ/929/147 : Luminous globular clusters in NGC 5128 (Dumont+, 2022)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID The H21/22 identifier (G1)
12- 20 F9.5 deg RAdeg [200.5/202.6] Right Ascension (J2000)
22- 30 F9.5 deg DEdeg [-43.8/-42] Declination (J2000)
32- 36 F5.2 mag gmag [17.6/22.7] Apparent g band AB magnitude
38- 42 F5.2 mag rmag [16.9/21.9] Apparent r band AB magnitude
44- 47 F4.2 mag g-r0 [0.03/1.01] Intrinsic (g-r) color
49- 55 F7.2 mag u-z0 [1/3.6]?=9999 Intrinsic (u-z) color
57- 60 I4 km/s RVel1 [102/878]?=9999 Magellan/M2FS radial velocity
62- 65 I4 km/s e_RVel1 [14/112]?=9999 Uncertainty in RVel1
67- 70 I4 km/s RVel2 [254/893]?=9999 AAT/AAOmega radial velocity
72- 75 I4 km/s e_RVel2 [10/29]?=9999 Uncertainty in RVel2
77- 79 I3 km/s WRVel [102/901] Weighted radial velocity
81- 82 I2 km/s e_WRVel [0/76] Uncertainty in WRVel
84-103 A20 --- Ref Radial velocity reference code(s) (1)
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Note (1): References as follows:
1 = van den Bergh et al. 1981AJ.....86...24V 1981AJ.....86...24V
2 = Hesser et al. 1986ApJ...303L..51H 1986ApJ...303L..51H
3 = Harris et al. 1992AJ....104..613H 1992AJ....104..613H
4 = Peng et al. 2004, J/ApJS/150/367
5 = Woodley et al. 2005AJ....129.2654W 2005AJ....129.2654W
6 = Rejkuba et al. 2007A&A...469..147R 2007A&A...469..147R
7 = Beasley et al. 2008, J/MNRAS/386/1443
8 = Woodley et al. 2010, J/ApJ/708/1335
9 = Woodley et al. 2010, J/AJ/139/1871
10 = Taylor et al. 2010ApJ...712.1191T 2010ApJ...712.1191T
11 = Voggel et al. 2020, J/ApJ/899/140
12 = Dumont et al. 2022, J/ApJ/929/147
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID The H21/22 identifier (G1)
12- 20 F9.5 deg RAdeg [199.7/204] Right Ascension (J2000)
22- 30 F9.5 deg DEdeg [-44.6/-41.5] Declination (J2000)
32- 36 F5.2 mag gmag [18.3/22.2] Apparent g band AB magnitude
38- 42 F5.2 mag rmag [17.86/21.1] Apparent r band AB magnitude
44- 47 F4.2 mag g-r0 [0.24/1.71] Intrinsic (g-r) color
49- 55 F7.2 mag u-z0 [1.5/3.5]?=9999 Intrinsic (u-z) color
57- 60 I4 km/s RVel1 [286/905]?=9999 Magellan/M2FS radial velocity
62- 65 I4 km/s e_RVel1 [14/122]?=9999 Uncertainty in RVel1
67- 70 I4 km/s RVel2 [257/758]?=9999 AAT/AAOmega radial velocity
72- 75 I4 km/s e_RVel2 [12/23]?=9999 Uncertainty in RVel2
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID The H21/22 identifier (G1)
12- 20 F9.5 deg RAdeg [199/204.1] Right Ascension (J2000)
22- 30 F9.5 deg DEdeg [-44.8/-40.9] Declination (J2000)
32- 38 F7.2 mag gmag [17.14/23.1]?=9999 Apparent g band AB magnitude
40- 46 F7.2 mag rmag [16.59/21.6]?=9999 Apparent r band AB magnitude
48- 51 I4 km/s WRVel [-418/3571] Weighted radial velocity
53- 55 I3 km/s e_WRVel [0/123] Uncertainty in WRVel
57- 62 A6 --- Type Source type ("star": 662 occurrences; or
"galaxy":12 occurrences)
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Global notes:
Note (G1): IDs H21-NNNNNN are <[HSS2021] NNNNNN> in Simbad (most of
H21-NNNNNN numbers in Table 3 are from Hughes+ 2021, J/ApJ/914/16,
table 4 or table 1 and 2, column "ID");
IDs H22-NNN are new here and are <[HSS2023] NNN> in Simbad.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 15-Apr-2025