J/ApJ/883/90 Mass segregation effect of X-ray sources in GCs. II. (Cheng+, 2019)
Exploring the mass segregation effect of X-ray sources in globular clusters.
II. The case of Terzan 5.
Cheng Z., Li Z., Fang T., Li X., Xu X.
<Astrophys. J., 883, 90 (2019)>
=2019ApJ...883...90C 2019ApJ...883...90C
ADC_Keywords: Clusters, globular; X-ray sources
Keywords: binaries: close ; globular clusters: individual (Terzan 5) ;
stars: kinematics and dynamics ; X-rays: binaries
Abstract:
Using archival Chandra observations with a total effective exposure of
734ks, we derive an updated catalog of point sources in the massive
globular cluster (GC) Terzan 5. Our catalog covers an area of
58.1arcmin2 (R≤4.3') with 489 X-ray sources, and more than 75% of
these sources are first detected in this cluster. We find significant
dips in the radial distribution profiles of X-ray sources in Terzan 5,
with the projected distance and width of the distribution dips for
bright (LX≳9.5x1030erg/s) X-ray sources larger than those of the
faint (LX≲9.5x1030erg/s) sources. By fitting the radial
distribution of the X-ray sources with a "generalized King model," we
estimated an average mass of 1.48±0.11 and 1.27±0.13M☉ for
the bright and faint X-ray sources, respectively. These results are in
agreement with that observed in 47 Tuc, which may suggest a universal
mass segregation effect for X-ray sources in GCs. Compared with 47Tuc,
we show that the two-body relaxation timescale of Terzan 5 is much
smaller, but its dynamical age is significantly younger than 47 Tuc.
These features suggest that the evolution of Terzan 5 is not purely
driven by two-body relaxation, and the tidal stripping effect also
plays an important role in accelerating the dynamical evolution of
this cluster.
Description:
The inner region of Terzan 5 has been frequently visited by Chandra,
primarily with its Advanced CCD Imaging Spectrometer (ACIS). A total
of 24 ACIS observations were taken between 2000 and 2016 July.
We selected 18 observations listed in Table 1.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
17 48 04.85 -24 46 44.6 Terzan 5 = Cl Terzan 5
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 18 Log of Chandra observations
table2.dat 230 489 Main Chandra source catalog
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See also:
VII/195 : Globular Clusters in the Milky Way (Harris, 1996)
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/other/Sci/292.2290 : Chandra compact binaries in 47 Tuc (Grindlay+, 2001)
J/ApJ/625/796 : X-ray sources in the globular cluster 47 Tuc (Heinke+, 2005)
J/ApJ/651/1098 : Faint X-ray sources in Terzan 5 (Heinke+, 2006)
J/ApJS/166/249 : Stellar dynamics & PMs in 47Tuc (McLaughlin+, 2006)
J/AJ/133/1287 : JHK photometry of 24 Galactic GCs (Valenti+, 2007)
J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)
J/ApJ/766/136 : Stellar encounter rates in Galactic GCs (Bahramian+, 2013)
J/ApJ/795/22 : Iron abundance of Terzan 5 stars (Massari+, 2014)
J/ApJS/228/2 : Chandra Deep Field-South survey: 7Ms sources (Luo+, 2017)
J/MNRAS/482/5138 : Galactic GC mean proper motions & veloc. (Baumgardt+, 2019)
J/ApJ/876/59 : Chandra X-ray sources in 47 Tuc (Cheng+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ObsID [3798/18881] Chandra observation identifier
7- 17 A11 "date" Date Date of the observation (UT)
19- 24 A6 --- Arrays Chandra arrays (always ACIS-S)
26- 30 F5.2 ks Ltime [13.8/84.2] Livetime
32- 39 F8.4 deg RAdeg Telescope optical pointing RA (J2000)
41- 48 F8.4 deg DEdeg Telescope optical pointing DEC (J2000)
50- 55 F6.2 deg Roll [86/276] Roll angle
57- 60 F4.2 s Ftime [0.8/3.1] Frame time
62- 67 F6.3 pix delX [-0.9/0.7] Right ascension shift δx
69- 74 F6.3 pix delY [-1.8/0.3] Declination shift δy
76- 81 F6.3 deg Rot [-0.07/0.2] Rotation angle
83- 88 F6.4 --- Scale [0.998/1.002] Scale factor of wcs_match
transformation matrix
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/489] X-ray catalog sequence number;
sorted by RA
5- 22 A18 --- Name IAU designation (HHMMSS.ss+DDMMSS.s; J2000)
24- 33 F10.6 deg RAdeg [266.9/267.1] Right Ascension (J2000)
35- 44 F10.6 deg DEdeg [-24.9/-24.7] Declination (J2000)
46- 48 F3.1 arcsec PosErr [0/0.4] The 1σ positional uncertainty
50- 54 F5.1 arcsec R [1/257.5] Projected distance from cluster
center (1)
56- 62 E7.1 --- PB [0/0.004] Binomial no-source probability
64- 70 F7.1 ct CNetT [5/9737] Full (0.5-8keV) band source counts
(aperture-corrected)
72- 78 F7.1 ct e_CNetT [0.9/9638] The 1σ lower bound of CNetT
80- 86 F7.1 ct E_CNetT [9/9837] The 1σ upper bound of CNetT
88- 94 F7.1 ct CNetS [-3/3613] Soft (0.5-2keV) band source
counts (aperture-corrected)
96- 102 F7.1 ct e_CNetS [0/3553]? The 1σ lower bound of CNetS
104- 110 F7.1 ct E_CNetS [1/3674]? The 1σ upper bound of CNetS
112- 117 F6.1 ct CNetH [-4.3/6124] Hard (2-8keV) band source
counts (aperture-corrected)
119- 124 F6.1 ct e_CNetH [0/6046]? The 1σ lower bound of CNetH
126- 131 F6.1 ct E_CNetH [1/6203]? The 1σ upper bound of CNetH
133- 140 E8.2 ph/cm2/s FluxT [2.9e-8/5.1e-5] Full (0.5-8keV) band
photon flux
142- 150 E9.2 ph/cm2/s FluxS [-1.1e-8/1.3e-5] Soft (0.5-8keV) band
photon flux
152- 160 E9.2 ph/cm2/s FluxH [-3.4e-8/3.7e-5] Hard (0.5-8keV) band
photon flux
162- 169 E8.2 10-7W LumT [9.3e+29/1.6e+33] The 0.5-8.0keV band
intrinsic luminosity (2)
171- 178 E8.2 10-7W LumS [2.8e+29/9.7e+32] The 0.5-2.0keV band
intrinsic luminosity (2)
180- 187 E8.2 10-7W LumH [4e+29/1.1e+33] The 2.0-8.0keV band
intrinsic luminosity (2)
189- 193 F5.2 [cm-2] NH [20.8/23.2] Absorption column density
195- 199 F5.2 [cm-2] e_NH [20.3/23.1]? The 1σ lower bound of NH
201- 205 F5.2 [cm-2] E_NH [21/23.3]? The 1σ upper bound of NH
207- 210 F4.2 --- PI [0.1/3.3] Photon Index of powerlaw model
212- 215 F4.2 --- e_PI [0.1/3]? The 1σ lower bound of PI
217- 220 F4.2 --- E_PI [0.4/3]? The 1σ upper bound of PI
222- 225 I4 --- dof [1179/1182] Cstatistic degrees of freedom
227- 230 I4 --- CStat [505/1096] Cstatistic values; using 1192
PHA bins
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Note (1): The cluster center coordinates adopted is
RAJ2000=17:48:04.85,DEJ2000=-24:46:44.60 (Lanzoni+ 2010ApJ...717..653L 2010ApJ...717..653L).
Note (2): Absorption-corrected. The X-ray luminosities were derived from the
model spectrum, assuming a distance of 5.9kpc (Valenti+ 2007, J/AJ/133/1287).
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History:
From electronic version of the journal
References:
Cheng et al. Paper I. 2019ApJ...876...59C 2019ApJ...876...59C Cat. J/ApJ/876/59
Cheng et al. Paper II. 2019ApJ...883...90C 2019ApJ...883...90C This catalog
Cheng et al. Paper III. 2020ApJ...892...16C 2020ApJ...892...16C
Cheng et al. Paper IV. 2020ApJ...904..198C 2020ApJ...904..198C
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 04-Mar-2021