J/ApJS/204/14 Deep Chandra observations of NGC 4649. I. (Luo+, 2013)
Deep Chandra monitoring observations of NGC 4649.
I. Catalog of source properties.
Luo B., Fabbiano G., Strader J., Kim D.-W., Brodie J.P., Fragos T.,
Gallagher J.S., King A., Zezas A.
<Astrophys. J. Suppl. Ser., 204, 14 (2013)>
=2013ApJS..204...14L 2013ApJS..204...14L
ADC_Keywords: Galaxies, nearby ; X-ray sources ; Active gal. nuclei ;
Binaries, X-ray ; Clusters, globular
Keywords: galaxies: active ; galaxies: individual (NGC 4649) ;
globular clusters: general ; X-rays: binaries ; X-rays: galaxies
Abstract:
We present the X-ray source catalog for the Chandra monitoring
observations of the elliptical galaxy, NGC 4649 (M60). The galaxy has
been observed with Chandra ACIS-S3 in six separate pointings, reaching
a total exposure of 299ks. There are 501 X-ray sources detected in the
0.3-8.0keV band in the merged observation or in one of the six
individual observations; 399 sources are located within the D25
ellipse. The observed 0.3-8.0keV luminosities of these 501 sources
range from 9.3x1036erg/s to 5.4x1039erg/s. The 90% detection
completeness limit within the D25 ellipse is 5.5x1037erg/s. Based
on the surface density of background active galactic nuclei (AGNs) and
detection completeness, we expect ∼45 background AGNs among the
catalog sources (∼15 within the D25 ellipse). There are nine sources
with luminosities greater than 1039erg/s, which are candidates for
ultraluminous X-ray sources. The nuclear source of NGC 4649 is a
low-luminosity AGN, with an intrinsic 2.0-8.0keV X-ray luminosity of
1.5x1038erg/s. The X-ray colors suggest that the majority of the
catalog sources are low-mass X-ray binaries (LMXBs). We find that 164
of the 501 X-ray sources show long-term variability, indicating that
they are accreting compact objects. We discover four transient
candidates and another four potential transients. We also identify 173
X-ray sources (141 within the D25 ellipse) that are associated with
globular clusters (GCs) based on Hubble Space Telescope and
ground-based data; these LMXBs tend to be hosted by red GCs. Although
NGC 4649 has a much larger population of X-ray sources than the
structurally similar early-type galaxies, NGC 3379 and NGC 4278, the
X-ray source properties are comparable in all three systems.
Description:
NGC 4649 has been covered by six Chandra observations with the S3 chip
of the Advanced CCD Imaging Spectrometer (ACIS), spanning 11 years:
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Obs. No. ObsID Start Date Exp (ks) Cleaned Exp (ks) PI
----------------------------------------------------------------------
1 785 2000 Apr 20 37.4 34.2 C. L. Sarazin
2 8182 2007 Jan 30 53.0 49.2 P. Humphrey
3 8507 2007 Feb 1 17.8 17.3 P. Humphrey
4 12976 2011 Feb 24 102.4 100.3 G. Fabbiano
5 12975 2011 Aug 8 86.1 84.4 G. Fabbiano
6 14328 2011 Aug 12 14.2 14.0 G. Fabbiano
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 79 501 Main Chandra Catalog: Basic Source Properties
table4.dat 148 501 Source Counts, Hardness Ratios, Color-Color Values
table5.dat 148 501 Source Counts, Hardness Ratios, Color Values: Obs1
table6.dat 148 501 Source Counts, Hardness Ratios, Color Values: Obs2
table7.dat 148 501 Source Counts, Hardness Ratios, Color Values: Obs3
table8.dat 148 501 Source Counts, Hardness Ratios, Color Values: Obs4
table9.dat 148 501 Source Counts, Hardness Ratios, Color Values: Obs5
table10.dat 148 501 Source Counts, Hardness Ratios, Color Values: Obs6
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2013)
J/MNRAS/416/155 : Globular clusters in five early-type galaxies (Faifer+, 2011)
J/A+A/525/A19 : Phot. of globulars in early galaxies (Chies-Santos+, 2011)
J/ApJ/736/65 : PNe in the Virgo elliptical gal. NGC 4649 (Teodorescu+, 2011)
J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)
J/ApJ/690/512 : LMXBs & globulars in early-type galaxies. II. (Humphrey, 2009)
J/ApJ/689/983 : LMXBs in early-type galaxies. I. Chandra (Humphrey+, 2008)
J/ApJ/682/135 : CCD photometry of M60 (Lee+, 2008)
J/ApJ/674/857 : RVs and CT1 magnitudes in M60 galaxy (Lee+, 2008)
J/ApJS/171/101 : GCs in the ACS Virgo cluster survey (Jordan+, 2007)
J/ApJ/662/525 : LMXBs in globular clusters of 5 galaxies (Kundu+, 2007)
J/ApJ/636/200 : XMM-Newton LMXB in NGC4649 (Randall+, 2006)
J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)
J/ApJ/602/231 : Chandra X-ray point sources in nearby gal. (Colbert+, 2004)
J/ApJ/600/729 : Chandra LMXB in NGC 4649 (Randall+, 2004)
J/MNRAS/355/608 : NGC 4649 (M60) globular clusters (Forbes+, 2004)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- XID [1/501] Source identification number
5- 20 A16 --- CXOU IAU name (JHHMMSS.s+DDMMSS)
22- 23 I2 h RAh [12] Hour of Right Ascension (J2000)
25- 26 I2 min RAm [43/44] Minute of Right Ascension (J2000)
28- 32 F5.2 s RAs Second of Right Ascension (J2000)
34 A1 --- DE- [+] Sign of the Declination (J2000)
35- 36 I2 deg DEd [11] Degree of Declination (J2000)
38- 39 I2 arcmin DEm [26/39] Arcminute of Declination (J2000)
41- 44 F4.1 arcsec DEs Arcsecond of Declination (J2000)
46- 49 F4.2 arcmin Dist [0/7.16] Radial distance of source from nucleus
51- 53 F3.1 arcsec epos [0.1/3.9] Positional uncertainty
55 A1 --- l_logLX The 3σ upper limit on logLX
56- 60 F5.2 [10-7W] logLX [36.9/39.8] log of 0.3-8keV X-ray luminosity;
in erg/s
62- 64 A3 --- Var [ VNPTC] Variability flag (1)
66- 69 F4.1 --- signi [0/14.4]?=-1 Maximum statistical significance (2)
71 I1 --- fp [0/3]? Positional flag: 0=outside, 3=inside (3)
73 I1 --- O [0/9]? Optical association note (4)
75- 79 A5 --- GC Globular Cluster identifier (5)
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Note (1): Variability flag as follows:
V = variable;
N = non-variable;
TC = transient candidate;
PTC = possible transient candidate.
Note (2): Of the full band (FB; 0.3-8keV) flux variation between any two
observations (see Section 3.4).
Note (3): Positional flag as follows:
0 = outside the D25 ellipses of NGC 4649 and NGC 4647
1 = within the D25 ellipses of NGC 4649 only
2 = within the D25 ellipses of NGC 4647 only
3 = within both D25 ellipses.
Note (4): The optical counterpart note as follows:
1 = the source may have a reliable HST globular counterpart (157 sources),
2 = the source may have a probable HST globular counterpart (4 sources),
3 = the source may have a ground-based globular counterpart (12 sources),
4 = the source may have a background AGN counterpart (17 sources),
5 = the source may have a counterpart that is an unusual dwarf galaxy
(1 source),
6 = the source may have a counterpart that is the nucleus of NGC 4649
(1 source),
7 = the source may have a counterpart that is a foreground star (2 sources),
8 = it has a high chance (>50%) of being associated with the companion
galaxy NGC 4647 (35 sources),
9 = it has a less significant chance of being associated with NGC 4647
(8 sources),
0 = it is associated with NGC 4649 but having no counterpart (264 sources)
Note (5): The globular cluster (GC) identification from Strader et al.
(2012ApJ...760...87S 2012ApJ...760...87S) or Lee et al. (2008, Cat. J/ApJ/674/857;
starting with the letter "L"; <[LHP2008] NNNNN> in Simbad); for the
173 X-ray sources with a GC counterpart.
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Byte-by-byte Description of file: table[4-9].dat table10.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- XID [1/501] Source identification number
5- 10 F6.1 ct FB ?=-1 Net full band 0.3-8 keV counts
12- 15 F4.1 ct e_FB ?=-1 Lower 1σ uncertainty on FB (6)
17- 20 F4.1 ct E_FB ?=-1 Upper 1σ uncertainty on FB (6)
22- 27 F6.1 ct SB ?=-1 Net soft band 0.3-2 keV counts
29- 32 F4.1 ct e_SB ?=-1 Lower 1σ uncertainty on SB (6)
34- 37 F4.1 ct E_SB ?=-1 Upper 1σ uncertainty on SB (6)
39- 43 F5.1 ct HB ?=-1 Net hard band 2-8 keV counts
45- 48 F4.1 ct e_HB ?=-1 Lower 1σ uncertainty on HB (6)
50- 53 F4.1 ct E_HB ?=-1 Upper 1σ uncertainty on HB (6)
55- 60 F6.1 ct SB1 ?=-1 Net 0.3-1 keV counts
62- 65 F4.1 ct e_SB1 ?=-1 Lower 1σ uncertainty on SB1 (6)
67- 70 F4.1 ct E_SB1 ?=-1 Upper 1σ uncertainty on SB1 (6)
72- 77 F6.1 ct SB2 ?=-1 Net 1-2 keV counts
79- 82 F4.1 ct e_SB2 ?=-1 Lower 1σ uncertainty on SB2 (6)
84- 87 F4.1 ct E_SB2 ?=-1 Upper 1σ uncertainty on SB2 (6)
89- 93 F5.2 --- HR ?=-1 Hardness ratio; (HB-SB)/(HB+SB)
95- 99 F5.2 --- e_HR ?=-1 Lower 1σ uncertainty on HR
101-105 F5.2 --- E_HR ?=-1 Upper 1σ uncertainty on HR
107-111 F5.2 --- SC ?=-1 Soft X-ray color; (SB2-SB1)/FB
113-117 F5.2 --- e_SC ?=-1 Lower 1σ uncertainty on SC
119-123 F5.2 --- E_SC ?=-1 Upper 1σ uncertainty on SC
125-129 F5.2 --- HC ?=-1 Hard X-ray color; (HB-SB2)/FB
131-135 F5.2 --- e_HC ?=-1 Lower 1σ uncertainty on HC
137-141 F5.2 --- E_HC ?=-1 Upper 1σ uncertainty on HC
143 A1 --- l_logLX The 3σ upper limit on logLX
144-148 F5.2 [10-7W] logLX [36.9/40]?=-1 log of 0.3-8keV X-ray luminosity;
(in erg/s)
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Note (6): A blank value in the uncertainty of the X-ray counts indicates
the main value is an upper limit.
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History:
From electronic version of the journal
References:
Strader et al. Paper II: HST imaging of GCs. 2012ApJ...760...87S 2012ApJ...760...87S
Cat. J/ApJ/760/87
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Mar-2013