J/ApJS/212/13 ChIcAGO. I. Sample and initial results (Anderson+, 2014)
Chasing the Identification of ASCA Galactic Objects (ChIcAGO): an X-ray survey
of unidentified sources in the Galactic Plane.
I. Source sample and initial results.
Anderson G.E., Gaensler B.M., Kaplan D.L., Slane P.O., Muno M.P.,
Posselt B., Hong J., Murray S.S., Steeghs D.T.H., Brogan C.L., Drake J.J.,
Farrell S.A., Benjamin R.A., Chakrabarty D., Drew J.E., Finley J.P.,
Grindlay J.E., Lazio T.J.W., Lee J.C., Mauerhan J.C., van Kerkwijk M.H.
<Astrophys. J. Suppl. Ser., 212, 13 (2014)>
=2014ApJS..212...13A 2014ApJS..212...13A
ADC_Keywords: X-ray sources ; Cross identifications ; Photometry, infrared ;
Surveys ; Galactic plane
Keywords: surveys; X-rays: binaries; X-rays: galaxies; X-rays: general;
X-rays: stars
Abstract:
We present the Chasing the Identification of ASCA Galactic Objects
(ChIcAGO) survey, which is designed to identify the unknown X-ray
sources discovered during the ASCA Galactic Plane Survey (AGPS).
Little is known about most of the AGPS sources, especially those that
emit primarily in hard X-rays (2-10keV) within the Fx∼10-13 to
10-11erg/cm2/s X-ray flux range. In ChIcAGO, the subarcsecond
localization capabilities of Chandra have been combined with a
detailed multiwavelength follow-up program, with the ultimate goal of
classifying the >100 unidentified sources in the AGPS. Overall to
date, 93 unidentified AGPS sources have been observed with Chandra as
part of the ChIcAGO survey. A total of 253 X-ray point sources have
been detected in these Chandra observations within 3' of the original
ASCA positions. We have identified infrared and optical counterparts
to the majority of these sources, using both new observations and
catalogs from existing Galactic plane surveys. X-ray and infrared
population statistics for the X-ray point sources detected in the
Chandra observations reveal that the primary populations of Galactic
plane X-ray sources that emit in the Fx∼10-13 to 10-11 erg/cm2/s
flux range are active stellar coronae, massive stars with strong
stellar winds that are possibly in colliding wind binaries, X-ray
binaries, and magnetars. There is also another primary population that
is still unidentified but, on the basis of its X-ray and infrared
properties, likely comprises partly Galactic sources and partly active
galactic nuclei.
Description:
A total of 93 AGPS (Advanced Satellite for Cosmology and Astrophysics
(ASCA) Galactic Plane Survey; Sugizaki et al. 2001, Cat. J/ApJS/134/77)
sources have been observed with Chandra as part of the ChIcAGO survey,
of which 84 were imaged with ACIS-S and 9 were imaged with HRC-I. The
ChIcAGO Chandra observations took place over a 3.5yr period, from 2007
January to 2010 July (see table 1).
The optical and NIR photometric observations presented in this paper
were obtained using instruments on the 6.5m, Baade Magellan telescope,
located at Las Campanas Observatory, Chile. The NIR photometry,
1-2.5um, was obtained using Persson's Auxiliary Nasmyth Infrared
Camera (PANIC) on Baade. Optical photometric observations of the
counterparts were obtained utilizing several Magellan instruments
depending on availability. These included the Inamori Magellan Areal
Camera and Spectrograph (IMACS) and the Raymond and Beverly Sackler
Magellan Instant Camera (MagIC) on the Baade telescope. These
instruments provide access to different photometric filters including
Bessel B, V, and R and CTIO I.
The Chandra positions of 10 ChIcAGO sources were observed with the
ATCA (1.4, 2.4, 4.8, and 8.6GHz) on 2008 January 21 and on 2008 April 11.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 198 259 ChIcAGO MAP X-ray Results, including the position,
position errors, net counts and quantile analysis
values for each ChIcAGO source
table2.dat 160 74 ChIcAGO sources with >20 X-ray counts and their
infrared properties
table5.dat 113 46 Properties of optical counterparts, where they
exist, for all ChIcAGO sources with >20 X-ray counts
table7.dat 79 118 Likely optical and infrared counterparts of
secondary (<20 X-ray counts) ChIcAGO Sources
table9.dat 67 37 Radio counterparts to ChIcAGO sources
table12.dat 115 176 Confirmed and tentative identifications of the
AGPS sources, including both literature and
ChIcAGO survey identifications
refs.dat 69 67 References
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
IX/45 : The Chandra Source Catalog, Release 1.1 (Evans+, 2012)
IX/41 : XMM-Newton Serendipitous Source Catalogue 2XMMi-DR3 (XMM-SSC, 2010)
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
VI/117 : Observation Log from ASCA (PLAIN Center, 2001)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+, 1998)
III/205 : H-alpha Stars in Northern Milky Way (Kohoutek+, 1997)
J/ApJ/701/811 : Chandra observations of INTEGRAL sources (Tomsick+, 2009)
J/A+A/505/405 : A catalogue of Spitzer dark clouds (Peretto+, 2009)
J/AJ/131/2525 : MAGPIS 20cm survey (Helfand+, 2006)
J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006)
J/ApJ/607/904 : Chandra obs. of Trifid nebula (Rho+, 2004)
J/PASJ/56/965 : X-ray properties of ASCA objects (Fukazawa+, 2004)
J/ApJS/134/77 : ASCA Galactic Plane Survey faint X-ray sources (Sugizak+, 2001)
J/ApJ/488/224 : 4.85 GHz fluxes of H II regions (Kuchar+, 1997)
J/A+AS/118/329 : MOST supernova remnant catalogue (MSC) (Whiteoak+, 1996)
http://irsa.ipac.caltech.edu/data/SPITZER/GLIMPSE/ : GLIMPSE Spitzer data
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 - 4 A4 --- --- [AX J]
5- 15 A11 --- AXJ AGPS source identifier (AX JHHMMSS+DDMM)
( in Simbad)
17 A1 --- f_AXJ [n] n: No source detected by Chandra
19- 23 I5 --- ObsID Chandra observation identification number
25- 34 A10 "YYYY/MM/DD" Date Date of the observation
36- 41 A6 --- Inst Chandra instrument used (ACIS-S or HRC-I)
43- 47 F5.2 ks Exp [0.9/10.1] Exposure time
49- 63 A15 --- ChI ChIcAGO identifier (JHHMMSS+DDMM_NN)
64 A1 --- f_ChI [d*] Unreliable source (1)
66- 67 I2 h RAh ? Hour of Right Ascension (J2000) (2)
69- 70 I2 min RAm ? Minute of Right Ascension (J2000) (2)
72- 76 F5.2 s RAs ? Second of Right Ascension (J2000) (2)
78 A1 --- DE- Sign of the Declination (J2000)(2)
79- 80 I2 deg DEd ? Degree of Declination (J2000) (2)
82- 83 I2 arcmin DEm ? Arcminute of Declination (J2000) (2)
85- 88 F4.1 arcsec DEs ? Arcsecond of Declination (J2000) (2)
90- 93 F4.2 arcmin Offset [0.1/3.1]? Offset from ASCA position (3)
95- 97 F3.1 arcsec ePosw ? Wav positional error (4)
99-101 F3.1 arcsec ePos ? Total positional error (4)
103-107 F5.1 ct NC.f [2.6/326]? Net 0.3-8 keV full band counts (5)
109-112 F4.1 ct e_NC.f ? Lower Uncertainty in NC.f
114-117 F4.1 ct E_NC.f ? Upper uncertainty in NC.f
119-123 F5.1 ct NC.s [0/280]? Net soft 0.5-2 keV band counts (5)
125-128 F4.1 ct e_NC.s ? Lower uncertainty in NC.s
130-133 F4.1 ct E_NC.s ? Upper uncertainty in NC.s
135-139 F5.1 ct NC.h [0/182]? Net hard 2-8 keV band counts (5)
141-144 F4.1 ct e_NC.h ? Lower uncertainty in NC.h
146-149 F4.1 ct E_NC.h ? Upper uncertainty in NC.h
151-153 F3.1 keV E50 [0.6/7]? Median energy of the photons
detected in 0.3-8 keV band
155-157 F3.1 keV e_E50 ? Uncertainty in E50
159-161 F3.1 --- QR [0.5/3]? Quartile ratio E25/E75 (6)
163-165 F3.1 --- e_QR ? Uncertainty in QR
167-181 A15 --- CXO Chandra source catalog (CSC) identifier (7)
183-198 A16 --- 2XMMi 2XMMi-DR3 identifier (8)
--------------------------------------------------------------------------------
Note (1):
* = source has a probability of false detection that is >1e-5.
d = source falls in the chip gap between ACIS-S CCDs 6 and 7.
Note (2): From wavdetect.
Note (3): The offset between the ChIcAGO source and the original AGPS source
position published by Sugizaki et al. (2001, Cat. J/ApJS/134/77).
Note (4): positional errors:
wav = 95% position error circle of the ChIcAGO source wavdetect
position. This was calculated using Equation 5 of Hong et al.
(2005ApJ...635..907H 2005ApJ...635..907H).
Total = 95% position error circle of the ChIcAGO source taking into account
the wavdetect position error and the absolute astrometric accuracy
of Chandra.
Note (5): The source counts were calculated using a source region with a
radius equal to 95% of the PSF at 1.5 keV. The total counts have
been background subtracted and the upper and lower 1σ
confidence limits were calculated using Gehrels (1986) statistics.
Note (6): The quartile ratio is the ratio of the E25 (energy of the 25%
photon detected) and E75 (energy of the 75% photon detected) used
in quantile analysis: 3*(E25-0.3)/(E75-0.3). See Section 2.3.1
for further details.
Note (7): The corresponding Chandra Source Catalog name (Evans et al.
2010ApJS..189...37E 2010ApJS..189...37E; see also Cat. IX/45).
Note (8): The corresponding 2XMMi DR3 name (Watson et al. 2009,
Cat. J/A+A/493/339).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- ChI ChIcAGO identifier (1)
16- 20 A5 --- n_2MASS NIR data code (2)
22- 37 A16 --- 2MASS 2MASS identifier; 2MASS J (1)
39 A1 --- l_Jmag Limit flag on Jmag
40- 45 F6.2 mag Jmag [7/22]? The J band magnitude
47- 50 F4.2 mag e_Jmag [0/0.5]? Uncertainty in Jmag
52 A1 --- l_Hmag Limit flag on Hmag
53- 58 F6.2 mag Hmag [5/21]? The H band magnitude
60- 63 F4.2 mag e_Hmag [0/0.4]? Uncertainty in Hmag
65 A1 --- l_Kmag Limit flag on Kmag
66- 71 F6.2 mag Kmag [4/19]? The K band magnitude
73- 76 F4.2 mag e_Kmag [0/0.5]? Uncertainty in Kmag
78- 87 A10 "YYYY/MM/DD" Date ? Date of PANIC observation
88 A1 --- --- [/]
89-90 I2 --- Day ? Second day of observation
92-107 A16 --- SSTGLM GLIMPSE (II/293) identifier; SSTGLMC G (1)
109-113 F5.2 mag [3.6] [6.7/14.4]? GLIMPSE 3.6um band magnitude
115-118 F4.2 mag e_[3.6] [0.03/0.2]? Uncertainty in [3.6]
120 A1 --- f_[3.6] [d] source in Archive for [3.6] (3)
122-126 F5.2 mag [4.5] [6.3/14.1]? GLIMPSE 4.5um band magnitude
128-131 F4.2 mag e_[4.5] [0.04/0.2]? Uncertainty in [4.5]
133 A1 --- f_[4.5] [d] source in Archive for [4.5] (3)
135-140 F6.3 mag [5.8] [5.4/12.5]? GLIMPSE 5.8um band magnitude
142-145 F4.2 mag e_[5.8] ? Uncertainty in [5.8]
147 A1 --- f_[5.8] [d] source in Archive for [5.8] (3)
149-153 F5.2 mag [8.0] [5.3/11.8]? GLIMPSE 8.0um band magnitude
155-158 F4.2 mag e_[8.0] ? Uncertainty in [8.0]
160 A1 --- f_[8.0] [d] source in Archive for [8.0] (3)
--------------------------------------------------------------------------------
Note (1): The wavdetect position of ChI J165646-4239_1 and the position of the
quoted 2MASS source agree within 4σ. We have listed this 2MASS
source as a possible counterpart as it is considered to be the same
as the quoted GLIMPSE source, which does agree within 3σ of the
wavdetect position. The quoted NIR magnitudes of ChI J181116-1828_2
and ChI J185643+0220_2, obtained with PANIC, are limits due to the
counterparts being blended. The H-band PANIC observation of
ChI J194152+2251_2 took place on 2007-07-31, whereas the other bands
were observed on 2007-07-29.
Note (2): Data from which the counterpart near-infrared magnitudes were
obtained. If three letters are listed this indicates that the
magnitudes were obtained from different datasets. This order
corresponds to the J, H and Ks magnitude order. The marks are:
M = 2MASS Point Source Catalog (Skrutskie et al. 2006, Cat. VII/233);
P = PANIC Magellan observations.
* = likely blended or, particularly in the case of ChI J194152+2251_2,
perhaps extended
** = the counterpart has a low sigma detection of >1.5σ for the
respective background plus RMS estimate.
Note (3): indicates source from the GLIMPSE archives (more complete, less
reliable) rather than the catalogs (which are more reliable). In these
cases the GLIMPSE archive source's names begin with SSTGLMA G.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- ChI ChIcAGO identifier (JHHMMss+DDMM_N)
16- 27 A12 --- USNO USNO-B1.0 identifier
29- 36 A8 --- OFlag Optical data source flag(s) (1)
38 A1 --- l_Bmag Limit flag on Bmag
40- 44 F5.2 mag Bmag [9.63/23.5]? B-band magnitude (2)
46- 48 F3.1 mag e_Bmag [0.3/0.3]? Bmag uncertainty (2)
50 A1 --- l_Vmag Limit flag on Vmag
52- 56 F5.2 mag Vmag [19.73/25]? V-band magnitude
58- 61 F4.2 mag e_Vmag [0.03/0.5]? Vmag uncertainty
63 A1 --- l_Rmag Limit flag on Rmag
65- 69 F5.2 mag Rmag [9.08/25]? R-band magnitude (2)
71- 74 F4.2 mag e_Rmag [0.03/0.3]? Rmag uncertainty (2)
76 A1 --- l_Imag Limit flag on Imag
78- 82 F5.2 mag Imag [8.85/23.4]? I-band magnitude
84- 87 F4.2 mag e_Imag [0.03/0.3]? Imag uncertainty
89-113 A25 --- Date Date(s) of the MagIC and IMACS observations
--------------------------------------------------------------------------------
Note (1): Catalog or observations from which the counterpart optical
magnitudes were obtained; if 4 ymbols are listed this indicates that
the magnitudes were obtained from different data sets. This order
corresponds to the B, V, R and I magnitude order. The symbols are:
U = USNO B1 Catalog (Monet et al. 2003, Cat. I/284),
A = MagIC Magellan observations,
I = IMACS Magellan observations,
NA = no data for the corresponding magnitude.
Note (2): The USNO-B1.0 B and R band magnitudes listed are the second epoch
B and R magnitudes (Monet et al. 2003, Cat. I/284).
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ChI ChIcAGO identifier
17- 28 A12 --- USNO USNO-B1.0 identifier (Cat. I/284)
30- 33 F4.2 arcsec UOff [0.03/1.2]? ChIcAGO and USNO positional offset
35- 50 A16 --- 2MASS 2MASS identifier; 2MASS J (Cat. II/246)
52- 55 F4.2 arcsec 2Off [0.08/1]? ChIcAGO and 2MASS positional offset
57- 73 A17 --- SSTGLM GLIMPSE identifier (Cat. II/293)
74 A1 --- f_SSTGLM [*] Source from GLIMPSE Archive (1)
76- 79 F4.2 arcsec GOff [0.02/1.2]? ChIcAGO & GLIMPSE positional offset
--------------------------------------------------------------------------------
Note (1): Those GLIMPSE counterpart names marked with a * are from the
archives (more complete, less reliable) rather than the catalogs (more
reliable). In these cases the archival GLIMPSE source's names begins
with "SSTGLMA G".
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- ChI ChIcAGO identifier(s) (1)
21- 30 A10 --- Survey Radio Survey or observations (2)
32- 54 A23 --- Radio Radio source identifier
56- 59 A4 --- Type Radio source type (3)
61 A1 --- Loc [ACKL] Location (4)
63- 67 A5 --- Ref Reference(s) (see refs.dat file) (5)
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Note (1): The names of the ChIcAGO sources with radio counterparts.
If all the ChIcAGO sources in a Chandra observation of an AGPS source
are coincident with the radio counterpart, then the range of suffixes
are listed in parentheses. If only a subset of the ChIcAGO sources
detected in a given Chandra observation are coincident with the radio
counterpart, then only those suffixes are listed.
Note (2): The radio Galactic plane surveys or observations visually
inspected as follows:
MGPS = Molonglo Galactic Plane Survey (VIII/82)
90 = 90cm Multi-configuration Very Large Array survey of the Galactic Plane
MAGPIS = the Multi-Array Galactic Plane Imaging Survey (J/AJ/131/2525)
VGPS = VLA Galactic Plane Survey;
ATCA = Australia Telescope Compact Array observations obtained for radio
follow-up of ChIcAGO sources (see Sections 2.4.2 and 3.4).
Note (3): Type of radio source as follows:
SNR = supernova remnant;
HII = HII region;
MS = massive star;
CWB = colliding wind binary;
IRDC = Infrared Dark Cloud;
AGN = likely active galactic nuclei based on a core-lobe morphology;
D = diffuse;
Arc = diffuse emission with an arc or shell morphology;
Com = compact;
ND = no detection in the case of the ATCA observations.
Note (4): Position of the ChIcAGO source relative to the radio source as
follows:
C = coincident;
A = adjacent;
L = limb (usually the limb or edge of a SNR, arc/shell structured diffuse
emission or HII region);
K = core of a possible AGN given the apparent core-lobe morphology.
Note (5): Many additional references to the SNRs are compiled in Green (2009,
Cat. VII/253).
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Byte-by-byte Description of file: table12.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 - 4 A4 --- --- [AX J]
5- 15 A11 --- AXJ AGPS identifier (AX JHHMMSS+DDMM)
17- 19 A3 --- --- [ChI]
21- 44 A24 --- ChI ChIcAGO identifier (1)
46- 62 A17 --- Type Source type (2)
64-100 A37 --- AName Most commonly used identifier(s)
102-106 A5 --- Ref Reference(s) (see refs.dat file) (3)
107-108 A2 --- f_Ref Source identified in J/ApJS/134/77 (4)
110-115 A6 --- Flag Source type flag (5)
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Note (1): The equivalent ChIcAGO name of the AGPS source. All ChIcAGO
sources with >20 X-ray counts are listed. In a few cases there is more
than one ChIcAGO source listed for a given AGPS source. For a given
identified H II region, all of the ChIcAGO sources contributed to the
X-ray emission originally detected with ASCA in the AGPS. In these
cases the ChIcAGO source name suffixes are listed in parentheses. If a
suffix is listed before the parentheses then this ChIcAGO source
corresponds to an X-ray source whose stellar type is listed in column
"Type", before the H II classification.
Note (2): The source type abbreviations are:
ASC = active stellar corona;
AGN = active galactic nucleus;
CV = cataclysmic variable;
CWB = colliding-wind binary;
H II = young and massive stars in the H II region named in the 4th column;
HMXB = high-mass X-ray binary;
LBV = luminous blue variable;
LMXB = low-mass X-ray binary;
Magnetar = magnetar;
MS = massive star;
MS-O = massive O-type star;
ND = no ChIcAGO sources detected in the Chandra
observation (no detection);
PMS = pre-main sequence star;
PSR = X-ray emission from a rotation-powered pulsar;
PWN = pulsar wind nebula;
SNR = supernova remnant;
SyXB = symbiotic X-ray binary,
U = unknown
WR = Wolf-Rayet star.
The other abbreviations are the spectral type of the stellar
counterpart.
Note (3): Those archival AGPS sources and identified ChIcAGO sources used in
the statistical analysis in Section 4.2 have two references in this
Table, the first being the paper describing an X-ray fit from which
we derived an absorbed X-ray flux, and the second being the paper
from which the NIR counterpart (J, H, Ks magnitudes) information
was obtained. All the longer-wavelength IR counterpart information
(3.6, 4.5, 5.8, and 8.0 micron magnitudes) was gathered from the
GLIMPSE catalogs and archives.
Note (4): The * and ** symbols indicate those AGPS sources that were correctly
and incorrectly identified by Sugizaki et al. (2001,
Cat. J/ApJS/134/77), respectively.
Note (5): Flags that correspond to the identification properties of the AGPS
and ChIcAGO sources. One flag is listed for each of the first three
columns.
I = Identified sources through work in the ChIcAGO survey;
T = Tentatively identified sources using the X-ray and infrared population
statistics in Section 4.2;
F = AGPS sources for which only ChIcAGO sources with ≤20 X-ray counts
were detected. These include AGPS sources where no sources were
detected in the corresponding ChIcAGO Chandra observations but excludes
those AGPS sources that have been identified as H II regions;
R = Figure 8 Region IV sources;
N = Unconfirmed classification type;
n = no flag.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode Bibcode
24- 48 A25 --- Aut Author's name(s)
51- 69 A19 --- Comm Comment
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Jun-2014