J/ApJ/635/214 Chandra X-ray sources and NIR identifications (Ebisawa+, 2005)
Chandra deep X-ray observation of a typical galactic plane region and
near-infrared identification.
Ebisawa K., Tsujimoto M., Paizis A., Hamaguchi K., Bamba A., Cutri R.,
Kaneda H., Maeda Y., Sato G., Senda A., Ueno M., Yamauchi S., Beckmann V.,
Courvoisier T.J.-L., Dubath P., Nishihara E.
<Astrophys. J., 635, 214-242 (2005)>
=2005ApJ...635..214E 2005ApJ...635..214E
ADC_Keywords: X-ray sources ; Photometry, infrared
Keywords: galaxies: active - Galaxy: structure - X-rays: stars
Abstract:
Using the Chandra Advanced CCD Imaging Spectrometer Imaging array
(ACIS-I), we have carried out a deep hard X-ray observation of the
Galactic plane region at (l,b)~(28.5°, 0.0°), where no
discrete X-ray source had been reported previously. We have detected
274 new point X-ray sources (4σ confidence), as well as strong
Galactic diffuse emission within two partially overlapping ACIS-I
fields (∼250arcmin2 in total). The point-source sensitivity was
3x10-15ergs/s/cm2 in the hard X-ray band (2-10keV) and
2x10-16ergs/s/cm2 in the soft band (0.5-2keV). The sum of all the
detected point-source fluxes accounts for only 10% of the total X-ray
flux in the field of view.
Following up the Chandra observation, we have performed a
near-infrared (NIR) survey with SofI at ESO/NTT. Almost all the soft
X-ray sources have been identified in the NIR, and their spectral
types are consistent with main-sequence stars, suggesting that most of
them are nearby X-ray-active stars.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 145 274 Detected Source List
table2.dat 78 32398 SOFI NIR source catalog
--------------------------------------------------------------------------------
See also:
B/chandra : The Chandra Archive Log (CXC, 2002-)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Sequential identification number (1)
5 A1 --- f_Seq [TE] Flag on Seq (2)
7- 9 A3 --- AO Announcement of Opportunity round
11- 12 I2 h RAh Hour of Right Ascension (J2000)
14- 15 I2 min RAm Minute of Right Ascension (J2000)
17- 21 F5.2 s RAs Second of Right Ascension (J2000)
23 A1 --- DE- Sign of the Declination (J2000)
24 I1 deg DEd Degree of Declination (J2000)
26- 27 I2 arcmin DEm Arcminute of Declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of Declination (J2000)
34- 37 F4.2 arcsec ePos Positional error
39- 42 F4.1 --- Sig Total band σ significance
44- 47 F4.1 --- SigS Soft band σ significance
49- 52 F4.1 --- SigH Hard band σ significance
54- 58 F5.1 10-5ct/s Ct Total band normalized counts
60- 64 F5.1 10-5ct/s CtS Soft band normalized counts
66- 70 F5.1 10-5ct/s CtH Hard band normalized counts
72- 76 F5.2 --- HR Hardness ratio, (H-S)/(H+S)
78- 81 F4.2 --- e_HR Error in HR
83- 89 E7.1 mW/m2 FSoft Soft band (0.5-2keV) flux (3)
91- 97 E7.1 mW/m2 FHard Hard band (2-10keV) flux (3)
99-122 A24 --- NIRID Near-IR counterpart identification (4)
124-127 F4.2 arcsec Sep ? Near-IR counterpart separation
129-133 F5.2 mag Jmag ? SOFI or 2MASS J band magnitude (5)
135-139 F5.2 mag Hmag ? SOFI or 2MASS H band magnitude (5)
141-145 F5.2 mag Ksmag ? SOFI or 2MASS Ks band magnitude (5)
--------------------------------------------------------------------------------
Note (1): Sources are identified as CXOGPE JHHMMSS.s+DDMMSS in Simbad.
Note (2): Flag as follows:
T = shows significant time variation
E = extended source
Note (3): In units of erg/s/cm^2.
Note (4): SNNNNNN (SOFI ID) and/or JHHMMSSss+DDMMSSs (2MASS ID) of the NIR
source within 1" from the Chandra position.
"No" means that the source is in the SOFI field of view,
but there are no SOFI counterparts.
"OoF" means that the source is out of the SOFI field,
and no 2MASS counterparts.
Note (5): 2MASS magnitudes are taken for stars brighter than 10mag, since
SOFI starts to saturate for <10mag (see Fig. 5).
99.99 indicates that the source is not detected in this band.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- SOFI SOFI NIR star identification number (1)
7- 8 I2 h RAh Hour of Right Ascension (J2000)
10- 11 I2 min RAm Minute of Right Ascension (J2000)
13- 18 F6.3 s RAs Second of Right Ascension (J2000)
20 A1 --- DE- Sign of the Declination (J2000)
21- 22 I2 deg DEd Degree of Declination (J2000)
24- 25 I2 arcmin DEm Arcminute of Declination (J2000)
27- 31 F5.2 arcsec DEs Arcsecond of Declination (J2000)
34- 38 F5.2 mag Jmag ?=99.99 The J band magnitude (2)
42- 46 F5.2 mag Hmag ?=99.99 The H band magnitude (2)
50- 54 F5.2 mag Kmag ?=99.99 The Ks band magnitude (2)
58- 73 A16 --- 2MASS 2MASS Identification name (within 0.5")
76- 78 I3 --- Seq ? Chandra identification number (within 1") (3)
--------------------------------------------------------------------------------
Note (1): Sources identified as SNNNNN in table1, NIRID column
Note (2): 99.99 indicates that the source is not detected in this band.
Note (3): The Seq number is defined in Table 1.
--------------------------------------------------------------------------------
Acknowledgements: Ken Ebisawa, ebisawa(at)isas.jaxa.jp
(End) Patricia Vannier [CDS] 19-Dec-2005