J/A+A/459/777 X-ray sources in Sagittarius and Carina dSph (Cignoni+, 2006)
A search for stellar X-ray sources in the Sagittarius and Carina dwarf galaxies.
I. X-ray observations.
Ramsay G., Wu K.
<Astron. Astrophys., 459, 777-781 (2006)>
=2006A&A...459..777R 2006A&A...459..777R
ADC_Keywords: Galaxies, nearby ; X-ray sources
Keywords: galaxies: dwarf - galaxies: individual: Sagittarius -
galaxies: individual: Carina - X-rays: binaries - X-rays: galaxies
Abstract:
ROSAT observations found no convincing evidence for X-ray sources
located in local dwarf spheroidal galaxies (dSph). Now with more
sensitive instruments on board Chandra and XMM-Newton we can reach
fainter luminosity levels. We report on an observation of the
Sagittarius (Sgr) dSph made using Chandra and an observation of the
Carina (Car) dSph made using XMM-Newton. Our observations are
sensitive to sources with X-ray luminosities in the 0.1-10keV band of
∼1x1032erg/s and 3x1034erg/s for the Sgr and Car fields
respectively. We have identified a total of 80 sources in the Sgr
field and 53 sources in the Car field. Although the source numbers are
roughly consistent with the expected number of background AGN, we
found a small fraction of X-ray sources which were soft and could be
located in the host dSph. Follow-up optical/IR observations may help
to identify their optical counterparts and hence determine their
nature.
Description:
Sgr was observed with Chandra ACIS-I for 30ks on 2003 Sep. 3.
Car was observed by XMM-Newton on 2005 May 25 for 41.7ks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 91 80 The X-ray sources found in the Chandra
observations of the Sgr field
tablea2.dat 87 53 The X-ray sources in the Carina field as
detected using XMM-Newton
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See also:
J/AJ/110/1141 : Variables in the Sagittarius dSph (Mateo+ 1995)
J/AJ/119/1760 : M54 and Sgr dSph VI photometry (Layden+, 2000)
J/A+A/414/503 : Abundances in the Sgr dSph (Bonifacio+, 2004)
J/AJ/130/2677 : Stars in the Carina dSph galaxy field (Majewski+, 2005)
J/A+A/465/815 : Abundances of Sgr dSph stars (Sbordone+, 2007)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number, [RW2006c] Sgr NN
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 27 F4.1 arcsec DEs Declination (J2000)
29- 33 F5.1 10-4ct/s CR0.3-8 Count rate in 0.3-8keV band (ct/10ks)
35- 37 F3.1 10-4ct/s e_CR0.3-8 rms uncertainty on CR0.3-8keV
39- 42 F4.1 10-4ct/s CR0.3-1 Count rate in 0.3-1keV band
44- 46 F3.1 10-4ct/s e_CR0.3-1 rms uncertainty on CR0.3-1keV
48- 51 F4.1 10-4ct/s CR1-2 Count rate in 1-2keV band
53- 55 F3.1 10-4ct/s e_CR1-2 rms uncertainty on CR1-2keV
57- 60 F4.1 10-4ct/s CR2-8 Count rate in 2-8keV band
62- 64 F3.1 10-4ct/s e_CR2-8 rms uncertainty on CR2-8keV
66- 70 F5.2 --- HR1 Hardness ratio, HR1=(H-M)/(H+M+S) (1)
72- 75 F4.2 --- e_HR1 rms uncertainty on HR1
77- 81 F5.2 --- HR2 Hardness ratio, HR2=(M-S)/(H+M+S) (1)
83- 86 F4.2 --- e_HR2 rms uncertainty on HR2
88- 91 F4.1 mag Rmag ? Magnitude, close to the UCAC2 R magnitude
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Note (1): Hardness ratios, where HR1=(H-M)/(H+M+S) and HR2=(M-S)/(H+M+S),
where H is the counts in the 2-8 keVband, M the counts in the
1-2keV band and S the counts in the 0.3-1keV band.
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Sequential number, [RW2006c] Car NN
4 I1 h RAh Right ascension (J2000)
6- 7 I2 min RAm Right ascension (J2000)
9- 12 F4.1 s RAs Right ascension (J2000)
14 A1 --- DE- Declination sign (J2000)
15- 16 I2 deg DEd Declination (J2000)
18- 19 I2 arcmin DEm Declination (J2000)
21- 24 F4.1 arcsec DEs Declination (J2000)
26- 29 F4.1 ct/ks CR0.2-10 Count rate in 0.2-10keV band (1)
31- 33 F3.1 ct/ks e_CR0.2-10 rms uncertainty on CR0.2-10keV
35- 38 F4.1 ct/ks CR0.2-1 Count rate in 0.2-1keV band (1)
40- 42 F3.1 ct/ks e_CR0.2-1 rms uncertainty on CR0.2-1keV
44- 47 F4.1 ct/ks CR1-2 Count rate in 1-2keV band (1)
49- 51 F3.1 ct/ks e_CR1-2 rms uncertainty on CR1-2keV
53- 56 F4.1 ct/ks CR2-10 Count rate in 2-10keV band (1)
58- 60 F3.1 ct/ks e_CR2-10 rms uncertainty on CR2-10keV
62- 66 F5.2 --- HR1 Hardness ratio, HR1=(H-M)/(H+M+S) (2)
68- 71 F4.2 --- e_HR1 rms uncertainty on HR1
73- 77 F5.2 --- HR2 Hardness ratio, HR2=(M-S)/(H+M+S) (2)
79- 82 F4.2 --- e_HR2 rms uncertainty on HR1
84- 87 F4.1 mag Rmag ? Magnitude, close to UCAC2 R magnitude
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Note (1): The count rates refer to that detected in the EPIC MOS(1+2) detector,
or the equivalent if detected only in the EPIC pn detector.
Note (2): Hardness ratios, where HR1=(H-M)/(H+M+S) and HR2=(M-S)/(H+M+S),
where H is the counts in the 2-10keV band, M the counts in the
1-2keV band and S the counts in the 0.2-1keV band.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-May-2007