J/ApJS/269/9 Opt-IR counterparts of Chandra sources in CygOB2 (Guarcello+, 2023)
Optical and infrared counterparts of the X-ray sources detected in the Chandra
Cygnus OB2 Legacy Survey.
Guarcello M.G., Drake J.J., Wright N.J., Naylor T., Flaccomio E.,
Kashyap V.L., Garcia-Alvarez D.
<Astrophys. J. Suppl. Ser., 269, 9 (2023)>
=2023ApJS..269....9G 2023ApJS..269....9G
ADC_Keywords: X-ray sources; Cross identifications; Photometry, ugriz;
Spectral types; Stars, masses; Stars, ages; Extinction
Keywords: Astronomy databases ; Catalogs
Abstract:
The young massive OB association Cygnus OB2, in the Cygnus X complex,
is the closest (∼1400pc) star-forming region to the Sun hosting
thousands of young low-mass stars and up to 1000 OB stars, among which
are some of the most massive stars known in our Galaxy. This region
holds great importance for several fields of modern astrophysics, such
as the study of the physical properties of massive and young low-mass
stars and the feedback provided by massive stars on star and planet
formation processes. Cyg OB2 has been recently observed with
Chandra/ACIS-I as part of the 1.08Ms Chandra Cygnus OB2 Legacy
Project. This survey detected 7924 X-ray sources in a square degree
area centered on Cyg OB2. Since a proper classification and study of
the observed X-ray sources also requires the analysis of their optical
and infrared counterparts, we combined a large and deep set of optical
and infrared catalogs available for this region with our new X-ray
catalog. In this paper we describe the matching procedure and present
the combined catalog containing 5703 sources. We also briefly discuss
the nature of the X-ray sources with optical and infrared counterparts
using their position in the color-magnitude and color-color diagrams.
Description:
The Chandra Cyg OB2 Legacy survey design employed 36 pointings of 30ks
exposure each. The full survey exposure was 1.08Ms, covering about
1deg2 centered at 20:33:12+41:19:00, and was performed over a
6-week period from 2010 January to March, employing the Advanced CCD
Imaging Spectrometer (ACIS-I). The X-ray catalog contains 7924 sources.
See Section 2.
The optical-infrared (OIR) catalog used in this work contains
photometric data retrieved from several publicly available catalogs:
from observations taken with the Optical System for Imaging and low
Resolution Integrated Spectroscopy (OSIRIS), mounted on the 10.4m Gran
Telescopio CANARIAS (GTC) of the Spanish Observatorio del Roque de los
Muchachos in La Palma compiled by Guarcello+ (2012, J/ApJS/202/19) in
riz bands, the public catalogs SDSS/DR8 (Aihara+ 2011ApJS..193...29A 2011ApJS..193...29A ;
see II/306) in ugriz bands, IPHAS/DR2 (Drew+ 2005MNRAS.362..753D 2005MNRAS.362..753D &
Barentsen+ 2014, II/321) in r',i' and Hα bands, and UKIDSS/GPS
(Hewett+ 2006MNRAS.367..454H 2006MNRAS.367..454H & Lucas+ 2008, II/316) and 2MASS/PSC
(Cutri+ 2003, II/246) in JHK bands, and from the Spitzer Legacy Survey
of the Cygnus X region (Beerer+ 2010, J/ApJ/720/679) in IRAC and MIPS
24um bands. See Section 3.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
20 33 12.00 +41 19 00.0 Ass Cyg OB 2 = NAME VI Cygni
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 454 5590 Main table of the merged optical, infrared, and
X-rays catalog of Cygnus OB2
tablea2.dat 413 5590 Secondary table of the merged optical, infrared,
and X-rays catalog of Cygnus OB2
--------------------------------------------------------------------------------
Description of files:
cygob2legacyprojectmaintable.fits.gz and
cygob2legacyprojectsecondarytable.fits.gz are the original FITS files as
sent by the author.
See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/306 : The SDSS Photometric Catalog, Release 8 (Adelman-McCarthy+, 2011)
II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)
II/321 : IPHAS DR2 Source Catalogue (Barentsen+, 2014)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
J/AJ/101/1408 : Massive stars in Cyg OB2. (Massey+ 1991)
J/A+A/464/211 : Chandra and NIR obs. of Cyg OB2 (Albacete Colombo+, 2007)
J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)
J/MNRAS/380/1467 : AGN in supercluster A901/2 (Gilmour+, 2007)
J/ApJS/169/401 : ChaMP X-ray point source catalog (Kim+, 2007)
J/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)
J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)
J/A+A/521/A18 : Blue stars with disk phot. in NGC 6611 (Guarcello+, 2010)
J/ApJ/713/871 : Star-forming region Cyg-OB2 from X-ray (Wright+, 2010)
J/ApJS/202/19 : riz photometry in Cyg OB2 (Guarcello+, 2012)
J/ApJ/773/135 : Disk-bearing stars in Cygnus OB2 (Guarcello+, 2013)
J/ApJS/209/28 : MYStIX Wide-Field NIR data: crowded fields (King+, 2013)
J/ApJS/209/30 : MYStIX project: Bayesian matching (Naylor+, 2013)
J/MNRAS/443/2907 : 3D extinction map of northern Galactic plane (Sale+, 2014)
J/MNRAS/449/741 : The massive star population of Cygnus OB2 (Wright+, 2015)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID [1/5712] Progressive number ID (ID)
6- 9 I4 --- [WDG2023] [1/7922] X-ray source ID in Wright+ 2023,
J/ApJS/269/7 catalog (CXO_ID)
11- 19 F9.5 deg RAdeg [307.5/310] Source right ascension (J2000)
(RA)
21- 28 F8.5 deg DEdeg [40.6/42] Source declination (J2000) (DEC)
30- 39 A10 --- Class Source classification according to
Kashyap+ 2023, J/ApJS/269/10 Bayesian
method ("member", "background" or
"foreground") (CLASSIFICATION)
41- 47 F7.4 mag Av [0.05/29.5]? Individual extinction in the V
band for members calculated adopting the
Fukugita+ 1996AJ....111.1748F 1996AJ....111.1748F extinction
law in SDSS bands (AV)
49- 56 F8.5 mag e_Av [0.01/91]? Av uncertainty (AV_ERR)
58- 69 A12 --- f_Av Tag explaining how AV is calculated
(AV_TAG) (1)
71- 80 F10.6 Msun Mass [0.1/110]? Source mass calculated adopting
the Fukugita+ 1996AJ....111.1748F 1996AJ....111.1748F
extinction law in SDSS bands (MASS)
82- 91 F10.5 [Myr] logAge [0.1/9.1]? Log of source age calculated
adopting the Fukugita+ 1996AJ....111.1748F 1996AJ....111.1748F
extinction law in SDSS bands (AGE)
93- 101 F9.6 [Lsun] logLum [-1.7/6.2]? Log of luminosity (LOGL)
103- 140 A38 --- Disk Tag indicating whether the source has a
disk (DISK) (2)
142- 155 A14 --- SpT Source spectral type based on spectroscopic
studies (SPT)
157- 164 A8 --- r_SpT Reference for spectral classification
(SPT_TAG) (3)
166- 172 F7.4 mag AvF07 [0.07/29]? Individual extinction in the V
band for members calculated adopting the
Fitzpatrick & Massa 2007, J/ApJ/663/320
extinction law in SDSS bands (AV_FITZ)
174- 181 F8.5 mag e_AvF07 [0.02/39]? AvF07 uncertainty (AVERRFITZ)
183- 192 F10.6 Msun MassF07 [0.1/110]? Source mass calculated adopting
the Fitzpatrick & Massa 2007, J/ApJ/663/320
extinction law in SDSS bands (MASS_FITZ)
194- 203 F10.5 [Myr] logAgeF07 [0.1/9.1]? Log of source age calculated
adopting the Fitzpatrick & Massa
2007, J/ApJ/663/320 extinction law in
SDSS bands (AGE_FITZ)
205- 213 F9.6 [Lsun] logLF07 [-1.7/7]? log of luminosity with F07
extinction law (LOGL_FITZ)
215- 221 F7.4 mag umag [15.9/26.8]? Magnitude in SDSS u band (MAGU)
223- 231 F9.6 mag e_umag [0.01/14]? Uncertainty on umag (ERRMAGU)
233- 239 F7.4 mag gmag [14.5/26.4]? Magnitude in SDSS g-band (MAGG)
241- 248 F8.6 mag e_gmag [0.009/10]? Uncertainty on gmag (ERRMAGG)
250- 256 F7.4 mag rmag [12/25.8]? Magnitude in SDSS r-band (MAGR)
258- 265 F8.6 mag e_rmag [0.0008/3]? Uncertainty on rmag (ERRMAGR)
267- 273 F7.4 mag imag [11.9/24]? Magnitude in SDSS i-band (MAGI)
275- 282 F8.6 mag e_imag [0.0007/3]? Uncertainty on imag (ERRMAGI)
284- 290 F7.4 mag zmag [12/22.3]? Magnitude in SDSS z-band (MAGZ)
292- 299 F8.6 mag e_zmag [0.0009/1]? Uncertainty on zmag (ERRMAGZ)
301- 307 F7.4 mag Jmag [4.6/20.1]? J-band magnitude from the best
NIR catalog (MAGJ)
309- 316 F8.6 mag e_Jmag [0.005/10]? Uncertainty on Jmag (ERRMAGJ)
318- 324 F7.4 mag Hmag [3.5/20]? H-band magnitude from the best
NIR catalog (MAGH)
326- 333 F8.6 mag e_Hmag [0.004/10]? Uncertainty on Hmag (ERRMAGH)
335- 341 F7.4 mag Kmag [2.7/18]? K band magnitude from the best
NIR catalog (MAGK)
343- 350 F8.6 mag e_Kmag [0.004/10]? Uncertainty on Kmag (ERRMAGK)
352- 358 F7.4 mag 3.6mag [5/17]? Spitzer/IRAC 3.6um band magnitude
(MAG1)
360- 367 F8.6 mag e_3.6mag [0.002/2]? Uncertainty on 3.6mag (ERRMAG1)
369- 375 F7.4 mag 4.5mag [4.3/17]? Spitzer/IRAC 4.5um band magnitude
(MAG2)
377- 384 F8.6 mag e_4.5mag [0.002/3]? Uncertainty on 4.5mag (ERRMAG2)
386- 392 F7.4 mag 5.8mag [2/16.2]? Spitzer/IRAC 5.8um band magnitude
(MAG3)
394- 401 F8.6 mag e_5.8mag [0.001/7]? Uncertainty on 5.8mag (ERRMAG3)
403- 409 F7.4 mag 8.0mag [2.2/17.1]? Spitzer/IRAC 8um band magnitude
(MAG4)
411- 418 F8.6 mag e_8.0mag [0.001/8]? Uncertainty on 8.0mag (ERRMAG4)
420- 426 F7.4 mag 24mag [0.8/13]? Spitzer/MIPS 24um band magnitude
(MAGMIPS)
428- 435 F8.6 mag e_24mag [0.003/8.2]? Uncertainty on 24mag
(ERRMAGMIPS)
437- 448 E12.6 mW/m2 FXfull [7.5e-17/4e-12] Energy flux in erg/cm2/s
in the X-ray full energy band
(Wright+ 2023, J/ApJS/269/7 and
Flaccomio+ 2023ApJS..269...12F 2023ApJS..269...12F)
(FLUXXRAYFULL)
450- 454 F5.2 --- Prob [-6/-2] Probability associated with the
null hypothesis for the X-ray source of
being a background fluctuation, calculated
using ACIS extract software
(Wright+ 2023, J/ApJS/269/7)
(PROBNOSOURCE)
--------------------------------------------------------------------------------
Note (1): Possible values as follows:
rri = from the r-i vs. i-z diagram (3379 occurrences)
NICER = Lombardi & Alves (2001A&A...377.1023L 2001A&A...377.1023L), applied on
2MASS photometry (716 occurrences)
NICER_UK = Lombardi & Alves (2001A&A...377.1023L 2001A&A...377.1023L), applied on
UKIDSS photometry (448 occurrences)
Spectroscopy = sources with known spectral type (107 occurrences)
Note (2): As in Guarcello+ 2013, J/ApJ/773/135 ; abbreviations are:
BWE = blue stars with excesses;
TD = transition disk;
PTD = pre-transition disk
Note (3): References as follows:
S58 = Schulte, D.H. 1958ApJ...128...41S 1958ApJ...128...41S (3+36 occurrences)
MT91 = Massey & Thompson 1991, J/AJ/101/1408 (57+36 occurrences)
C02 = Comeron+ 2002A&A...389..874C 2002A&A...389..874C (14 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID [1/5712] Identifier (ID)
6- 9 I4 [-] [WDG2023] [1/7922] X-ray source ID in Wright+
2023, J/ApJS/269/7 catalog (CXO_ID)
11- 17 F7.4 mag rmagOS [11.7/25.8]? Magnitude in OSIRIS r band
(MAGR_OS)
19- 26 F8.6 mag e_rmagOS [0.0008/1.3]? rmagOS uncertainty
(ERRMAGR_OS)
28- 34 F7.4 mag imagOS [11.3/24]? Magnitude in OSIRIS i band
(MAGI_OS)
36- 43 F8.6 mag e_imagOS [0.0009/1]? imagOS uncertainty
(ERRMAGI_OS)
45- 51 F7.4 mag zmagOS [10.7/22.3]? Magnitude in OSIRIS z band
(MAGZ_OS)
53- 60 F8.6 mag e_zmagOS [0.0009/1]? zmagOS uncertainty
(ERRMAGZ_OS)
62- 67 F6.3 --- Chi2 [1/35]? Combined chi2 parameter
describing the goodness of the PSF fit
on OSIRIS images
(Guarcello+ 2012, J/ApJS/202/19) (CHI)
69- 74 F6.3 --- Sharp [-8.5/31]? Sharp parameter from the
OSIRIS images
(Guarcello+ 2012, J/ApJS/202/19) (SHARP)
76- 82 F7.4 mag RmagIP [12/23.3]? Magnitude in IPHAS R band,
from DR2 if available otherwise DR1
(MAGR_IP)
84- 91 F8.6 mag e_RmagIP [0.0008/0.6]? RmagIP uncertainty
(ERRMAGR_IP)
93- 99 F7.4 mag ImagIP [0.001/20.7]? Magnitude in IPHAS I band,
from DR2 if available otherwise DR1
(MAGI_IP)
101- 108 F8.6 mag e_ImagIP [0.001/0.3]? ImagIP uncertainty
(ERRMAGI_IP)
110- 116 F7.4 mag HamagIP [11.8/22.3]? Magnitude in IPHAS Halpha
band, from DR2 if available otherwise
DR1 (MAGHA)
118- 125 F8.6 mag e_HamagIP [0.001/0.8]? HamagIP uncertainty
(ERRMAGHA)
127- 135 F9.6 mag umag [15.9/26.8]? Magnitude in SDSS/DR9 u
band (MAGU)
137- 145 F9.6 mag e_umag [0.01/13.1]? Uncertainty on umag
(ERRMAGU)
147- 155 F9.6 mag gmag [14.5/26.4]? Magnitude in SDSS/DR9 g
band (MAGG)
157- 164 F8.6 mag e_gmag [0.009/10]? Uncertainty on gmag
(ERRMAGG)
166- 174 F9.6 mag rmag [13.9/23.3]? Magnitude in SDSS/DR9 r
band (MAGR_SD)
176- 183 F8.6 mag e_rmag [0.005/9]? Uncertainty on rmag
(ERRMAGR_SD)
185- 191 F7.4 mag imag [12.5/23]? Magnitude in SDSS/DR9 i band
(MAGI_SD)
193- 200 F8.6 mag e_imag [0.0007/4.1]? Uncertainty on imag
(ERRMAGI_SD)
202- 208 F7.4 mag zmag [12.2/20.8]? Magnitude in SDSS/DR9 z
band (MAGZ_SD)
210- 217 F8.6 mag e_zmag [0.008/2]? Uncertainty on zmag
(ERRMAGZ_SD)
219- 222 I4 --- SDSSCl [-999/6] Classification based on SDSS
photometry (6=star, 1903 occurrences or
3=galaxy, 64 occurrences or
0=unknown, 10 occurrences) (SDSS_CLASS)
224- 230 F7.4 mag Jmag [4.6/18.7]? Magnitude in 2MASS J band
(MAGJ_2M)
232- 239 F8.6 mag e_Jmag [0.018/10]? Uncertainty on Jmag
(ERRMAGJ_2M)
241- 247 F7.4 mag Hmag [3.5/16.8]? 2MASS H-band magnitude
(MAGH_2M)
249- 256 F8.6 mag e_Hmag [0.01/10]? Uncertainty on Hmag
(ERRMAGH_2M)
258- 264 F7.4 mag Ksmag [2.7/16.7]? 2MASS Ks-band magnitude
(MAGK_2M)
266- 273 F8.6 mag e_Ksmag [0.01/10]? Uncertainty on Ksmag
(ERRMAGK_2M)
275- 277 A3 --- Qflg 2MASS JHK photometric quality flag;
see II/246 (PHQUAL)
279- 281 A3 --- Rflg Source of JHK default mag;
see II/246 (RDFLAG)
283- 285 A3 --- Bflg JHK components fit to source;
see II/246 (BLFLAG)
287- 289 A3 --- Cflg 2MASS artifact contamination, confusion;
see II/246 (CCFLAG)
291- 297 F7.4 mag JmagUK [12/20.1]? Magnitude in UKIDSS J band
(MAGJ_UK)
299- 306 F8.6 mag e_JmagUK [0.005/0.2]? JmagUK uncertainty
(ERRMAGJ_UK)
308- 314 F7.4 mag HmagUK [11.8/19]? Magnitude in UKIDSS H band
(MAGH_UK)
316- 323 F8.6 mag e_HmagUK [0.004/0.2]? HmagUK uncertainty
(ERRMAGH_UK)
325- 331 F7.4 mag KmagUK [10.7/18]? Magnitude in UKIDSS K band
(MAGK_UK)
333- 340 F8.6 mag e_KmagUK [0.004/0.2]? KmagUK uncertainty
(ERRMAGK_UK)
342- 348 F7.4 mag J-K [-0.13/6.4]? UKIDSS J-K color index
(COLJK_UK)
350- 357 F8.6 mag e_J-K [0.007/0.2]? J-K uncertainty
(ERRCOLJK_UK)
359- 365 F7.4 mag H-K [-0.02/2.7]? UKIDSS H-K color index
(COLHK_UK)
367- 374 F8.6 mag e_H-K [0.007/0.2]? H-K uncertainty
(ERRCOLHK_UK)
376 I1 --- MultOpt [0/2] The number of multiple
coincidences between the OSIRIS, IPHAS,
or SDSS counterparts of this source
(MULTI_OPT) (1)
378 I1 --- MultIR [0/2] The number of multiple
coincidences between the UKIDSS and
2MASS counterparts of this source
(MULTIUK2M) (1)
380- 381 I2 --- MultIROpt [-1/2] The number of multiple
coincidences between the optical and
infrared counterparts of this source
(MULTINIROPT) (1)
383- 384 I2 --- MultOIR-IRAC [-1/3] The number of multiple
coincidences between the optical+JHK and
IRAC counterparts of this source
(MULTIOIRIRAC) (1)
386- 387 I2 --- MultOIR-X [-4/4] The number of multiple
coincidences involving the OIR and X-ray
counterparts of this source
(MULTIOIRX) (1)
389- 395 F7.5 arcsec SepOIR-X [0.005/6.1]? Distance between the OIR
and the X-ray counterparts (DISTOIRX)
397- 399 F3.1 --- RelOIR-X [0/1] Reliability of the OIR vs. X-ray
coincidence as defined with the modified
Smith+ 2011MNRAS.416..857S 2011MNRAS.416..857S method
(RELOIRX)
401 I1 --- PMflg [0/1] Equal to 1 if the OIR and X-ray
counterparts have been matched by the PM
matching method (TAG_PM)
403 I1 --- Sflg [0/1] Equal to 1 if the OIR and X-ray
counterparts have been matched by the
modified Smith+ 2011MNRAS.416..857S 2011MNRAS.416..857S
method (TAG_SM)
405 I1 --- BIflg [0/1] Equal to 1 if the OIR and X-ray
counterparts have been matched by the
Bayesian matching procedure defined by
Naylor+ 2013, J/ApJS/209/30 applied
using the MAGI values (TAGNBI)
407 I1 --- BKflg [0/1] Equal to 1 if the OIR and X-ray
counterparts have been matched by the
Bayesian matching procedure defined by
Naylor+ 2013, J/ApJS/209/30 applied
using the MAGK values (TAGNBK)
409 I1 --- B1flg [0/1] Equal to 1 if the OIR and X-ray
counterparts have been matched by the
Bayesian matching procedure defined by
Naylor+ 2013, J/ApJS/209/30 applied
using the MAG1 values (TAGNBIRAC)
411 I1 --- Rel [0/1] Equal to 1 if the OIR-X-ray match
is "reliable" (RELIABLE_MATCH)
413 I1 --- XID [0/1] Equal to 1 if the source is a
multiple OIR vs. X-ray identification
(MULTIOIRX>1) and this coincidence
has been set as the most reliable by
visual inspection of positions and OIR
diagrams. Single matches always have
SUGGESTED_COUNTERPART=1
(SUGGESTED_COUNTERPART)
--------------------------------------------------------------------------------
Note (1): For single matches it is equal to 0
--------------------------------------------------------------------------------
Acknowledgements:
Mario Giuseppe Guarcello [mario.guarcello at inaf.it]
(End) Mario Giuseppe Guarcello [INAF-OAPA], E. Perret [CDS] 29-Jan-2024