J/ApJS/166/211 Chandra sources in Antennae galaxies, NGC 4038/39 (Zezas+, 2006)
Chandra monitoring observations of The Antennae galaxies.
I. Catalog of source properties.
Zezas A., Fabbiano G., Baldi A., Schweizer F., King A.R., Ponman T.J.,
Rots A.H.
<Astrophys. J. Suppl. Ser., 166, 211-248 (2006)>
=2006ApJS..166..211Z 2006ApJS..166..211Z
ADC_Keywords: X-ray sources
Keywords: galaxies: individual (NGC 4038/39)- galaxies: interactions -
galaxies: peculiar - X-rays: binaries -X-rays: galaxies
Abstract:
We present the properties of the discrete X-ray sources detected in
our monitoring survey of the Antennae galaxies with Chandra ACIS-S. We
detect ∼70 sources down to a typical luminosity of 7x1037ergs/s in
each of the six monitoring observations. In the co-added observation
(which has a total exposure of 411ks) we detect a total of 120
sources down to a luminosity of (2-5)x1037ergs/s, depending on the
local background. Fifteen sources have a strong extended component.
Fourteen of the pointlike sources have luminosities above
1039ergs/s, at least in one exposure, which qualifies them as
ultraluminous X-ray sources (ULXs). Ten of the ULXs show long-term
variability, while one is observed only once, suggesting that it is a
transient source. We find that 25 sources exhibit long-term
variability clearly associating them with accreting compact objects.
Twenty-one sources also show spectral variability. However, their
variability patterns are diverse, indicating that they belong to
different source classes. Finally, we find a weak excess of hard
sources at the low luminosities that we tentatively associate with
pulsar X-ray binaries.
Description:
The first Chandra observation of the Antennae was performed in 1999
December (Fabbiano et al., 2001ApJ...554.1035F 2001ApJ...554.1035F; Zezas et al.,
2002ApJ...577..710Z 2002ApJ...577..710Z, 2002ApJS..142..239Z 2002ApJS..142..239Z; Zezas & Fabbiano,
2002ApJ...577..726Z 2002ApJ...577..726Z). Following this pilot observation, the Antennae
were observed with Chandra on six more occasions between 2000 December
and 2001 November (Fabbiano et al., 2003ApJ...591..843F 2003ApJ...591..843F,
2004ApJ...605L..21F 2004ApJ...605L..21F). This survey consists of four additional
exposures of 70ks and two exposures of 35ks, resulting in a total
exposure time of 411ks. The time span between the long exposures was
a few months, while the shorter exposures were taken two days apart.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 25 7 Observation Log
table3.dat 88 120 Source and background apertures
table5.dat 103 127 Source Catalog
table6.dat 123 120 Source properties: Observation 1
table7.dat 123 120 Source properties: Observation 2
table8.dat 123 120 Source properties: Observation 3
table9.dat 123 120 Source properties: Observation 4
table10.dat 123 120 Source properties: Observation 5
table11.dat 123 120 Source properties: Observation 6
table12.dat 123 120 Source properties: Observation 7
table13.dat 123 120 Source properties: Combined Observation
table14.dat 132 120 Hardness Ratios: Observation 1
table15.dat 132 120 Hardness Ratios: Observation 2
table16.dat 132 120 Hardness Ratios: Observation 3
table17.dat 132 120 Hardness Ratios: Observation 4
table18.dat 132 120 Hardness Ratios: Observation 5
table19.dat 132 120 Hardness Ratios: Observation 6
table20.dat 132 120 Hardness Ratios: Observation 7
table21.dat 132 120 Hardness Ratios: Coadded Observation
table22.dat 101 78 Antennae Sources: Radial Profile fits
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See also:
J/AJ/109/960 : Young star clusters in The Antennae (Whitmore+ 1995)
J/ApJ/561/727 : BVI photometry in the Antennae galaxies (Zhang+, 2001)
J/AJ/124/1418 : Radio-optical identification of star clusters (Whitmore+ 2002)
J/ApJ/599/1049 : Supergiant molecular complexes in the Antennae (Wilson+, 2003)
J/AJ/127/660 : Photometry in southern tail of the Antennae (Saviane+, 2004)
J/ApJ/635/280 : Star clusters in the Antennae galaxies (Brandl+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Obs Observation number
3- 6 I4 --- ObsID Chandra observation ID
8- 17 A10 "YYYY/MM/DD" Obs.Date Observation date
19- 25 F7.1 s ExpTime Net exposure time
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [ZFB2006] Source number
6 A1 --- n_[ZFB2006] [ab] Note on [ZFB2006] (1)
8- 9 I2 h RAh Source aperture Right Ascension (J2000)
11- 12 I2 min RAm Source aperture Right Ascension (J2000)
14- 18 F5.2 s RAs Source aperture Right Ascension (J2000)
20 A1 --- DE- Source aperture Declination sign (J2000)
21- 22 I2 deg DEd Source aperture Declination (J2000)
24- 25 I2 arcmin DEm Source aperture Declination (J2000)
27- 30 F4.1 arcsec DEs Source aperture Declination (J2000)
32- 35 F4.2 arcsec MajAxis Source aperture semi-major axis
37- 40 F4.2 arcsec MinAxis Source aperture semi-minor axis
42- 46 F5.1 deg PA Source aperture position angle
48- 49 I2 h BRAh Background aperture Right Ascension (J2000)
51- 52 I2 min BRAm Background aperture Right Ascension (J2000)
54- 58 F5.2 s BRAs Background aperture Right Ascension (J2000)
60 A1 --- BDE- Background aperture Declination sign (J2000)
61- 62 I2 deg BDEd Background aperture Declination (J2000)
64- 65 I2 arcmin BDEm Background aperture Declinations (J2000)
67- 70 F4.1 arcsec BDEs Background aperture Declination (J2000)
72- 76 F5.2 arcsec BMaj ? Background aperture semi-major axis
78- 82 F5.2 arcsec BMin ? Background aperture semi-minor axis
84- 88 F5.1 deg BPA ? Background aperture position angle
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Note (1): Note as follows:
a = This source aperture does not include a circular region centered
at 12:01:54.788,-18:52:54.08 with a radius of 1.04"
b = This source aperture does not include an elliptical region
centered at 12:01:55.175,-18:52:47.93 with semi-major and
semi-minor axes of 1.37" and 1.32", respectively, and
position angle of 93.1°
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [ZFB2006] Source number (1)
6- 7 I2 --- [ZFR2002] ? Source number from Paper II,
Zezas et al., 2002ApJS..142..239Z 2002ApJS..142..239Z
9- 23 A15 --- CXC CXC source name (HHMMSS.s+DDMMSS) (3)
25- 26 I2 h RAh Hour of Right Ascension (J2000) (4)
28- 29 I2 min RAm Minute of Right Ascension (J2000) (4)
31- 34 F4.1 s RAs Second of Right Ascension (J2000) (4)
36 A1 --- DE- Sign of the Declination (J2000) (4)
37- 38 I2 deg DEd Degree of Declination (J2000) (4)
40- 41 I2 arcmin DEm Arcminute of Declination (J2000) (4)
43- 46 F4.1 arcsec DEs Arcsecond of Declination (J2000) (4)
48- 53 F6.1 ct OCts Full band (0.3-7.0keV) observed counts (5)
55- 58 F4.1 ct e_OCts Uncertainty in OCts (5)
60- 67 F8.4 ct BCts Full band background counts (5)
69- 73 F5.1 --- ApR ? Background to source aperture area ratio
75- 79 F5.2 [10-7W] logX ? Log of 0.1-10keV source luminosity (6)
81- 85 F5.2 [10-7W] e_logX ? Error in logX
87- 92 F6.2 --- Sig Significance in σ above local
background
94 A1 --- f_Sig [B] Indicates Sig>3σ
96- 97 A2 --- Ext [Y? ] Extended?
99-103 A5 --- Var [LSTV?, ] Variable? (7)
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Note (1): The last 7 entries detail the information relating to the fully
combined dataset (exposures 1-7). These sources were detected at least
3σ above the background in the fully combined observation
(exposures 1-7). Sources identified as [ZFB2006] N D in Simbad
Note (3): CXOAnt HHMMSS.s+DDMMSS.s in Simbad
Note (4): Of the source centroids from the combined dataset (Observations 2-7).
Note (5): Uncorrected for background and exposure effects.
Note (6): Absorption corrected assuming a power-law spectrum (Γ=1.7)
and Galactic line-of-sight HI column density (for variable sources
this is the average luminosity in the six observations).
Note (7): Variability flag as follows:
S = exhibits short variability
L = long term variability
T = transient candidate
V = variable
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Byte-by-byte Description of file: table[6-9].dat table1[0-3].dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [ZFB2006] Source number
5- 10 F6.1 ct FOCts The 0.3-7keV observed counts (1)
12- 15 F4.1 ct e_FOCts Error in FOCts
17- 21 F5.1 ct FBCts The 0.3-7keV background counts (2)
23- 26 F4.2 --- FArea The 0.3-7keV effective area relative to
observation 2 (3)
28- 33 F6.1 ct SOCts The 0.3-1.0keV observed counts (1)
35- 38 F4.1 ct e_SOCts Error in SOCts
40- 44 F5.1 ct SBCts The 0.3-1.0keV background counts (2)
46- 49 F4.2 --- SArea The 0.3-1.0keV effective area relative to
observation 2 (3)
51- 56 F6.1 ct MOCts The 1.0-2.5keV observed counts (1)
58- 61 F4.1 ct e_MOCts Error in MOCts
63- 67 F5.1 ct MBCts The 1.0-2.5keV background counts (2)
69- 72 F4.2 --- MArea The 1.0-2.5keV effective area relative to
observation 2 (3)
74- 79 F6.1 ct HOCts The 2.5-7keV observed counts (1)
81- 84 F4.1 ct e_HBCts Error in HBCts
86- 89 F4.1 ct HBCts The 2.5-7keV background counts (2)
91- 94 F4.2 --- HArea The 2.5-7keV effective area relative to
observation 2 (3)
96-101 F6.2 --- Sig Significance in σ above local
background
103 A1 --- f_Sig [B] Indicates Sig>|3σ|
105-109 F5.1 --- Var ? Variability significance in σ (4)
111 A1 --- f_Var [B] Indicates Var>|3σ|
113-117 F5.2 [10-7W] logX ? Log of the 0.1-10keV absorption
corrected luminosity (5)
119-123 F5.2 [10-7W] e_logX ? Error in LogX
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Note (1): Uncorrected for background.
Note (2): Not corrected for exposure effects
Note (3): Ratio of the effective area at the source position to the
effective area as the aimpoint of Observation 2.
Note (4): In the full band (0.3-7keV) and with respect to the previous
observation and after correcting for exposure effects.
Note (5): Based on the full band source and background intensities, the
effective area normalization factors, and assuming the same model
as in Table 5. In units of erg/s.
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Byte-by-byte Description of file: table1[4-9].dat table2[01].dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [ZFB2006] Source number
5- 9 F5.2 --- HR1 ? Standard (M-S)/(M+S) hardness ratio (1)
11- 14 F4.2 --- e_HR1 ? Error in HR1
16- 20 F5.2 --- HR2 ? Standard (H-M)/(H+M) hardness ratio (1)
22- 25 F4.2 --- e_HR2 ? Error in HR2
27- 31 F5.2 --- HR3 ? Standard (H-S)/(H+S) hardness ratio (1)
33- 36 F4.2 --- e_HR3 ? Error in HR3
38- 42 F5.2 --- BHR1 ? Bayesian method (M-S)/(M+S)
hardness ratio (1)
44- 47 F4.2 --- E_BHR1 ? Upper 1σ interval in BHR1
49- 52 F4.2 --- e_BHR1 ? Lower 1σ interval in BHR1
54- 58 F5.2 --- BHR2 ? Bayesian method (H-M)/(H+M)
hardness ratio (1)
60- 63 F4.2 --- E_BHR2 ? Upper 1σ interval in BHR2
65- 68 F4.2 --- e_BHR2 ? Lower 1σ interval in BHR2
70- 74 F5.2 --- BHR3 ? Bayesian method (H-S)/(H+S)
hardness ratio (1)
76- 79 F4.2 --- E_BHR3 ? Upper 1σ interval in BHR3
81- 84 F4.2 --- e_BHR3 ? Lower 1σ interval in BHR3
86- 90 F5.2 [-] C1 ? Bayesian method S/M color (1)
92- 95 F4.2 [-] E_C1 ? Upper 1σ interval in C1
97-100 F4.2 [-] e_C1 ? Lower 1σ interval in C1
102-106 F5.2 [-] C2 ? Bayesian method M/H color (1)
108-111 F4.2 [-] E_C2 ? Upper 1σ interval in C2
113-116 F4.2 [-] e_C2 ? Lower 1σ interval in C2
118-122 F5.2 [-] C3 ? Bayesian method S/H color (1)
124-127 F4.2 [-] E_C3 ? Upper 1σ interval in C3
129-132 F4.2 [-] e_C3 ? Lower 1σ interval in C3
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Note (1): Where S, M, H are the net source counts in the soft (0.3-1.0keV),
medium (1.0-2.5keV) and hard (2.5-7.0keV) band (exposure corrected
with respect to the reference point). We used exposure-corrected
source intensities in the calculation of the HR to compare directly
the hardness ratios between different observations.
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Byte-by-byte Description of file: table22.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- [ZFB2006] Source name
5- 9 F5.2 --- PSF Cash statistic for fit of the source radial
profile with model PSF
11 I1 --- dofPSF Degrees of freedom on PSF
13 A1 --- l_FWHM Limit flag on FWHM
14- 18 F5.2 pix FWHM FWHM of radial profile fit with Gaussian
plus background
20- 24 F5.2 pix e_FWHM ? Lower limit error in FWHM
26- 30 F5.2 pix E_FWHM ? Upper limit error in FWHM (1)
32- 36 F5.2 ct/pix Bgr Background for radial profile fit with
Gaussian plus background
38- 44 F7.2 ct/pix e_Bgr Lower limit error in Bgr
46- 49 F4.2 ct/pix E_Bgr ? Upper limit error in Bgr (1)
51- 55 F5.2 --- Gauss Cash statistic for radial profile fit with
Gaussian plus background model
57 I1 --- dofGauss Degrees of freedom on Gauss
59- 64 F6.2 pix FWHMc ? Core FWHM of radial profile fit with
Double Gaussian
66- 70 F5.2 pix e_FWHMc ? Lower limit error in FWHMc
72- 75 F4.2 pix E_FWHMc ? Upper limit error in FWHMc (1)
77- 80 F4.2 ct/pix FWHMw ? Wing FWHM of radial profile fit with
Double Gaussian
82- 86 F5.2 ct/pix e_FWHMw ? Lower limit error in FWHMw
88- 91 F4.2 ct/pix E_FWHMw ? Upper limit error in FWHMw (1)
93- 97 F5.2 --- Gauss1 ? Cash statistic for radial profile fit
with Double Gaussian model
99 I1 --- dofGauss1 ? Degrees of freedom on Gauss1
101 A1 --- Note [ANSd] Additional note (2)
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Note (1): A NULL value indicates that there is only a lower limit error on
the error which is given in the previous column.
Note (2): Additional note as follows:
A = The source is located on the arm of diffuse emission West of the
Northern nucleus
N = The source is located in the vicinity of the Northern nucleus
S = The source is located in the vicinity of the Southern nucleus
d = These two sources are very close to each other - source 28 is
present only in the 1st exposure
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 09-May-2008