J/ApJ/862/73 Deep Chandra obs. of X-ray point sources in M87 (Luan+, 2018)
Deep Chandra observations of X-ray point sources in M87.
Luan L., Jones C., Forman W.R., Bogdan A., Andrade-Santos F.,
Goulding A.D., Hickox R.C., Hou M., Li Z.
<Astrophys. J., 862, 73-73 (2018)>
=2018ApJ...862...73L 2018ApJ...862...73L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; X-ray sources ; Clusters, globular ;
Binaries, X-ray
Keywords: galaxies: elliptical and lenticular, cD; galaxies: individual: M87;
globular clusters: general; X-rays: binaries
Abstract:
We present a study of X-ray source populations in M87, the cD galaxy
of the Virgo cluster, using 12 archival Chandra observations with a
total exposure of ∼680ks spanning about a decade. A total of 346
point-like sources are detected down to a limiting 0.5-8keV luminosity
of 4x1037erg/s and out to a galactocentric radius of ∼40kpc. We
cross-correlate the X-ray sources with published catalogs of globular
clusters (GCs), derived from the ACS Virgo Cluster Survey and the Next
Generation Virgo Cluster Survey. This results in 122 matches, making
it one of the largest samples of GC-hosting X-ray sources in an
external galaxy. These sources, most likely low-mass X-ray binaries
(LMXBs), correspond to ∼5% of all known GCs within the Chandra
field-of-view. Conversely, ∼50% of the detected X-ray sources are
found in a GC. Moreover, red (metal-rich) GCs are ∼2.2 times more
likely to host an X-ray source than blue (metal-poor) GCs. We also
examine 76 currently known ultra-compact dwarf galaxies around M87 but
find no significant X-ray counterparts. After statistically accounting
for the cosmic X-ray background, we identify ∼110 field-LMXBs. The
GC-LMXBs and field-LMXBs differ in their luminosity function and
radial distribution, which indicates that the latter cannot be
primarily originated from GCs. Using another set of deep Chandra
observations toward ∼100kpc northwest of the M87 center, we
statistically constrain the abundance of field-LMXBs in the stellar
halo, which is consistent with that found in the central region. We
also identify 40 variable X-ray sources, among which one source is
likely a black hole binary residing in a GC.
Description:
The central region of M87 has been frequently observed by Chandra. In
this work, we utilized 12 Chandra observations (between 2000 Jul and
2010 Apr) taken with the Advanced CCD Imaging Spectrometer (ACIS),
which all have an exposure longer than 10ks and are publicly available
as of 2016. The total exposure is 677ks.
In addition to the 12 observations that together define the
"Center-Field," we also utilize 10 ACIS-I observations (between 2013
Aug and 2014 Mar) pointed toward a field (hereafter referred to as the
"Off-Field") ∼20' northwest to the nucleus of M87, with a total
exposure of ∼460ks.
See Table 1.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 53 22 Log of Chandra observations
table2.dat 99 346 X-ray point sources in the Center-Field
table3.dat 97 173 X-ray point sources in the Off-Field
table5.dat 28 299 Spurious sources
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
V/148 : The MORX catalogue (Flesch, 2016)
J/AJ/115/1801 : VRI photometry of M87 globular clusters (Harris+ 1998)
J/ApJ/513/733 : Globular cluster system in M87 (Kundu+, 1999)
J/MNRAS/328/461 : X-ray luminosities of early-type galaxies (O'Sullivan+, 2001)
J/ApJ/554/L129 : X-ray lum.-vel. dispersion relation (Mahdavi+, 2001)
J/ApJ/559/812 : Globular cluster system in M87 (Hanes+, 2001)
J/ApJ/613/279 : ACS Virgo Cluster Survey. III. M87 (Jordan+, 2004)
J/A+A/447/71 : CHANDRA X-ray point sources in Cen A (NGC 5128) (Voss+, 2006)
J/ApJS/169/401 : ChaMP X-ray point source catalog (Kim+, 2007)
J/ApJS/180/54 : Globular cluster cand. in ACS Virgo survey. (Jordan+, 2009)
J/ApJS/181/110 : Galactic center X-ray sources (Muno+, 2009)
J/ApJS/182/216 : Surface photometry of Virgo ellipticals (Kormendy+, 2009)
J/ApJ/704/1570 : Fitting LINERs within the AGN family (Gonzalez-Martin+, 2009)
J/ApJ/706/223 : X-ray point sources near the Galactic Center (Hong+, 2009)
J/ApJ/714/25 : AMUSE-Virgo survey. II. (Gallo+, 2010)
J/ApJS/187/135 : SEDs of weak AGNs associated with LINERs (Eracleous+, 2010)
J/ApJ/736/90 : Chandra X-ray sources of NGC 1399 (Paolillo+, 2011)
J/AJ/141/129 : Chandra Transmission Grating Data Cat. (Huenemoerder+, 2011)
J/AJ/144/11 : IR imaging, SEDs, Spitzer spectra of 22 AGNs (Mason+, 2012)
J/ApJ/773/L27 : Globular clusters in ACSVCS early-type galaxies (Park+, 2013)
J/ApJS/227/12 : NGVS XXV. Virgo globular clusters photometry (Powalka+, 2016)
J/ApJ/835/212 : Wide-field spectrosc. survey of GCs in Virgo (Ko+, 2017)
J/ApJ/835/223 : A catalog of nearby galaxies with Chandra obs. (She+, 2017)
J/ApJS/235/26 : Ultradeep cat. of X-ray point sources in the GC (Zhu+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Field c=center or o=off (see the "Description"
section above)
3- 7 I5 --- ObsID [1808/16593] Chandra obsID
9- 10 I2 h RAh [12] Hour of Right Ascension (J2000)
12- 13 I2 min RAm [30] Minute of Right Ascension (J2000)
15- 18 F4.1 s RAs Second of Right Ascension (J2000)
20 A1 --- DE- [+] Sign of Declination (J2000)
21- 22 I2 deg DEd [12] Degree of Declination (J2000)
24- 25 I2 arcmin DEm [16/40] Arcminute of Declination (J2000)
27- 28 I2 arcsec DEs Arcsecond of Declination (J2000)
30- 40 A11 "Y/M/D" Date Observation date (UT)
42- 47 F6.2 ks Exp [12.8/156.2] Exposure time
49- 53 A5 --- CCDs CCD identifier(s)
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Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/346] Sequential running number
5- 6 I2 h RAh [12] Hour of Right Ascension (J2000)
8- 9 I2 min RAm [29/31] Minute of Right Ascension (J2000)
11- 15 F5.2 s RAs Second of Right Ascension (J2000)
17 A1 --- DE- [+] Sign of Declination (J2000)
18- 19 I2 deg DEd [12] Degree of Declination (J2000)
21- 22 I2 arcmin DEm Arcminute of Declination (J2000)
24- 28 F5.2 arcsec DEs Arcsecond of Declination (J2000)
30- 33 F4.2 arcsec ePos [0.04/3.3] Positional error (1)
35 A1 --- l_S1 Upper limit flag for S1 (2)
37- 41 F5.1 10-7ph/cm2/s S1 [0.3/457] Photon Flux, 0.5-2keV
43- 46 F4.1 10-7ph/cm2/s E_S1 ? Upper uncertainty in S1
48- 51 F4.1 10-7ph/cm2/s e_S1 ? Lower uncertainty in S1
53 A1 --- l_S2 Upper limit flag for S2 (2)
55- 59 F5.1 10-7ph/cm2/s S2 [0.3/248] Photon Flux, 2-8keV
61- 63 F3.1 10-7ph/cm2/s E_S2 ? Upper uncertainty in S2
65- 67 F3.1 10-7ph/cm2/s e_S2 ? Lower uncertainty in S2
69- 73 F5.1 10-7ph/cm2/s S3 [0.3/715] Photon Flux, 0.5-8keV
75- 78 F4.1 10-7ph/cm2/s E_S3 Upper uncertainty in S3
80- 83 F4.1 10-7ph/cm2/s e_S3 Lower uncertainty in S3
85- 89 F5.1 10-15mW/m2 F0.5-8 [0.1/251] Unabsorbed energy flux, 0.5-8keV,
in units of 10-15erg/cm2/s
91- 95 F5.2 --- Ratio [1.5/12.5]? Max/Min Flux ratio (3)
97- 99 A3 --- Note Note(s) (4)
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Note (1): Positional error estimated by net counts and off-axis angle
in units of arcsecond.
Note (2): For sources undetected in a certain band for σ, a 3σ
upper limit is provided. In these cases the upper and lower
uncertainties are blank (null).
Note (3): Ratio of maximum flux to minimum flux as measured among the
individual observations, shown only for sources with significant
variability.
Note (4): Codes as follows:
G = denotes sources positionally coincident with an optically-identified
globular cluster (112+12 sources also variable in Table 2);
V = denotes sources with strong variability.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/299] Sequential running number
5- 6 I2 h RAh [12] Hour of Right Ascension (J2000)
8- 9 I2 min RAm [30/31] Minute of Right Ascension (J2000)
11- 15 F5.2 s RAs Second of Right Ascension (J2000)
17 A1 --- DE- [+] Sign of Declination (J2000)
18- 19 I2 deg DEd [12] Degree of Declination (J2000)
21- 22 I2 arcmin DEm [19/24] Arcminute of Declination (J2000)
24- 28 F5.2 arcsec DEs Arcsecond of Declination (J2000)
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Nomenclature notes:
In tables 2 and 3, sources are in Simbad
(based on the truncated coordinates).
In table 5, sources are <[LJF2018] JHHMMSS.ss+DDMMSS.ss> in Simbad.
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Jul-2019