J/ApJ/613/1179 X-ray sources in Galactic Center (Muno+, 2004)
The spectra and variability of X-ray sources in a deep Chandra observation of
the Galactic Center.
Muno M.P., Arabadjis J.S., Baganoff F.K., Bautz M.W., Brandt W.N.,
Broos P.S., Feigelson E.D., Garmire G.P., Morris M.R., Ricker G.R.
<Astrophys. J., 613, 1179-1201 (2004)>
=2004ApJ...613.1179M 2004ApJ...613.1179M
ADC_Keywords: X-ray sources ; Spectroscopy
Mission_Name: Chandra
Keywords: binaries: general - Galaxy: center - novae, cataclysmic variables -
X-rays: binaries - X-rays: stars
Abstract:
We examine the X-ray spectra and variability of the sample of X-ray
sources with LX∼1031-1033ergs/s identified within the inner 9'
of the Galaxy by Muno et al. Very few of the sources exhibit intraday
or intermonth variations.
Description:
Twelve separate pointings toward the Galactic center have been carried
out using the Advanced CCD Imaging Spectrometer imaging array (ACIS-I)
on board the Chandra X-Ray Observatory in order to monitor Sgr A*.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 152 566 Spectra of Individual Point Sources
table3.dat 137 64 Iron emission from sources with more than
160 net counts
table6.dat 71 44 Sources with short-term variability
table7.dat 60 75 Sources with long-term variability
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See also:
B/chandra : The Chandra Archive Log (CXC, 2002-)
J/ApJ/589/225 : Chandra X-ray sources toward Galactic Center (Feigelson+ 2003)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CXOGC IAU Designation
18- 21 I4 ct cts Net counts, 0.5-8.0keV
23 A1 --- l_PNH [<>e] Limit flag on PNH (1)
25- 29 F5.1 10+22/cm2 PNH Absorption, power component
31- 35 F5.1 10+22/cm2 PNHl Lower value of PNH interval
37- 41 F5.1 10+22/cm2 PNHh Upper value of PNH interval
43 A1 --- l_Gamma [<>e] Limit flag on Gamma (1)
45- 48 F4.1 --- Gamma Power-law photon index Γ
50- 53 F4.1 --- Gammal Lower value of Γ interval
55- 58 F4.1 --- Gammah Upper value of Γ interval
60- 64 F5.2 10-17W/m2 Pflux Power law flux (2)
66- 72 F7.2 10-17W/m2 uPflux De-absorbed power-law flux (2)
74- 77 I4 --- Pchi2 Chi-squared for power-law fit
79- 82 I4 --- d_Pchi2 Degrees of freedom for Pchi2
84 A1 --- l_TNH [<>e] Limit flag for TNH (1)
86- 90 F5.1 10+22/cm2 TNH Absorption for plasma model
92- 96 F5.1 10+22/cm2 TNHl Lower value of TNH interval
98-102 F5.1 10+22/cm2 TNHh Upper value of TNH interval
104 A1 --- l_kT [<>e] Limit flag for kT (1)
106-109 F4.1 keV kT Plasma temperature
111-114 F4.1 keV kTl Lower value of kT interval
116-119 F4.1 keV kTh Upper value of kT interval
121-125 F5.2 10-17W/m2 Tflux Plasma model flux (2)
127-133 F7.2 10-17W/m2 uTflux De-absorbed plasma model flux (2)
135-138 I4 --- Tchi2 Plasma model chi-squared
140-143 I4 --- d_Tchi2 Degrees of freedom for Tchi2
145 A1 --- f6.4 [yn-] Whether 6.4 keV Fe is detected
148 A1 --- f6.7 [yn-] Whether 6.7 keV Fe is detected
150-152 A3 --- Flags Flag for quality of spectrum (3)
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Note (1): The limit flag has the following meaning:
> = a lower limit,
< = an upper limit,
e = the uncertainty calculation failed to converge. If the flag is set, the
lower and upper uncertainties will be 0.
Note (2): In units of 10-14erg/cm2/s.
Note (3): Flags for the quality of the spectrum are defined as follows:
l = long-term variability;
s = short-term variability;
e = lies near the edge of the CCD;
c = may be blended with a nearby source.
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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- 16 A16 --- CXOGC IAU Designation
19- 22 F4.1 --- G6.4 Power-law photon index for
low-ionization Fe (6.4keV)
24- 26 F3.1 --- E_G6.4 Upper error limit on G6.4keV
28- 30 F3.1 --- e_G6.4 Lower error limit on G6.4keV
33 A1 --- l_F(6.4) Limit flag on F(6.4)
34- 37 F4.1 ct/m2/ks F(6.4) ? Flux at 6.4keV (G1)
39- 41 F3.1 ct/m2/ks E_F(6.4) ? Upper error limit on F(6.4)
43- 45 F3.1 ct/m2/ks e_F(6.4) ? Lower error limit on F(6.4)
47 A1 --- l_EW(6.4) Limit flag on EW(6.4)
48- 52 I5 eV EW(6.4) ? Equivalent width for low-ionization Fe
56- 59 F4.1 --- Dchi2(6.4) ? Δ(chi2) for low-ionization Fe (1)
62- 66 F5.3 --- P(6.4) ? Probability for low-ionization Fe (2)
69- 77 A9 --- chi2(6.4) Reduced chi-squared (χ2/dof)
79- 82 F4.1 --- G6.7 Power-law photon index for He-like Fe
(6.7keV)
84- 86 F3.1 --- E_G6.7 Upper error limit on G6.7
88- 90 F3.1 --- e_G6.7 Lower limit error on G6.7keV
93 A1 --- l_F(6.7) Limit flag on F(6.7)
94- 97 F4.1 ct/m2/ks F(6.7) ? Flux at 6.7keV (G1)
99-101 F3.1 ct/m2/ks E_F(6.7) ? Upper error limit on F(6.7)
103-105 F3.1 ct/m2/ks e_F(6.7) ? Lower error limit on F(6.7)
108 A1 --- l_EW(6.7) Limit flag on EW(6.7)
109-113 I5 eV EW(6.7) ? Equivalent width for He-like Fe
116-119 F4.1 --- Dchi2(6.7) ? Δ(chi2) for He-like Fe (1)
122-126 F5.3 --- P(6.7) ? Probability for He-like Fe (2)
129-137 A9 --- chi2(6.7) Reduced chi-squared (χ2/dof)
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Note (1): Difference of chi-squared with and without the line
Note (2): PFe refers to the chance probability that the line emission
could be produced by random variations in a featureless continuum.
Only sources with PFe<0.01 for a line at either 6.4 or 6.7keV are
listed in the table. Note that the line emission for those sources
with a best-fit power laws with Γ>4 should be viewed extremely
skeptically, because these steep spectra are background-dominated
above 6keV.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CXOGC IAU designation
17 A1 --- f_CXOGC [b] Flag on CXOGC (1)
19- 20 A2 --- fg [GC F] Location in the foreground of or
near the Galactic Center
23- 26 I4 --- ObsID Observation identification
27 A1 --- f_ObsID Flag on ObsID
30- 34 A5 --- Var Variability type (2)
37- 40 F4.1 ks Deltat ? Time interval
43 A1 --- l_Fmin ? Limit flag on Fmin
44- 46 I3 ct/m2/ks Fmin ? Minimum flux (G1)
48- 49 I2 ct/m2/ks E_Fmin ? Upper error limit on Fmin
51- 52 I2 ct/m2/ks e_Fmin ? Lower error limit on Fmin
55- 58 I4 ct/m2/ks Fmax ? Maximum flux (G1)
59 A1 --- f_Fmax Flag on Fmax (3)
60- 62 I3 ct/m2/ks E_Fmax ? Upper error limit on Fmax
64- 66 I3 ct/m2/ks e_Fmax ? Lower error limit on Fmax
69 A1 --- l_FR Limit flag on Fmax/Fmin ratio
70- 71 I2 --- FR ? Ratio Fmax/Fmin
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Note (1): The variability from these sources was identified via the K-S test
(Kolmogorov-Smirnov test), but not by the Bayesian blocks algorithm.
Note (2): If the Bayesian blocks code identified only two intervals with
differing count rates, then the variability was classified as a
"step" function. If it identified more than two intervals with
differing count rates, we defined the variability as a flare
Note (3): A "c" indicates that this flare consisted of five photons received
within 100s.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CXOGC IAU Designation
19- 20 A2 --- fg [GC F] Location in the foreground of
or near the Galactic Center
23- 26 I4 --- ObsIDmin ObsID of Minimum
27 A1 --- f_ObsIDmin Flag on ObsIDmin
30 A1 --- l_Fmin Limit flag on Fmin
31- 32 I2 ct/m2/ks Fmin Minimum flux (G1)
34- 35 I2 ct/m2/ks E_Fmin ? Upper error limit on Fmin
37- 38 I2 ct/m2/ks e_Fmin ? Lower error limit on Fmin
41- 44 I4 --- ObsIDmax ObsID of Maximum
45 A1 --- f_ObsIDmax Flag on ObsIDmax
47- 49 I3 ct/m2/ks Fmax Maximum flux (G1)
51- 52 I2 ct/m2/ks E_Fmax Upper error limit on Fmax
54- 55 I2 ct/m2/ks e_Fmax Lower limit error on Fmax
58 A1 --- l_FR Limit flag on Fmax/Fmin ratio
59- 60 I2 --- FR Ratio Fmax/Fmin
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Global notes:
Note (G1): count rate expressed in units of 10-7photons/cm2/s
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 09-Jun-2005