J/ApJ/690/295 Chandra observations of J1604+4314 supercluster (Kocevski+, 2009)
Chandra observations of the CL1604 supercluster at z=0.9: evidence for an
overdensity of active galactic nuclei.
Kocevski D.D., Lubin L.M., Gal R., Lemaux B.C., Fassnacht C.D.,
Squires G.K.
<Astrophys. J., 690, 295-318 (2009)>
=2009ApJ...690..295K 2009ApJ...690..295K
ADC_Keywords: Clusters, galaxy ; X-ray sources ; Redshifts ;
Cross identifications
Keywords: galaxies: clusters: general - large-scale structure of universe -
X-rays: galaxies: clusters
Abstract:
We present the results of Chandra observations of the Cl1604
supercluster at z∼0.9. The system is the largest structure mapped
at redshifts approaching unity, containing at least eight
spectroscopically confirmed galaxy clusters and groups. Using two 50ks
ACIS-I pointings we examine both the X-ray point-source population and
the diffuse emission from individual clusters in the system. Over an
area encompassing the entire supercluster (∼0.154deg2), we find a
2.5σ excess of point sources detected in the hard band (2-10keV)
relative to the number of sources found in blank fields observed by
Chandra. No such excess is observed in the soft band (0.5-2keV). The
hard-band source density is 1.47 times greater than that of a blank
field, in agreement with the previously reported correlation between
overdensity amplitude and cluster redshift. Using a maximum likelihood
technique, we have matched 112 of the 161 detected X-ray point sources
to optical counterparts and found 15 sources that are associated with
the supercluster. All 15 sources have rest-frame luminosities
consistent with emission from active galactic nuclei (AGNs).
Description:
Observations of the Cl1604 supercluster were carried out with
Chandra's Advanced CCD Imaging Spectrometer (ACIS) on 2006 June 23
(obsID 7343), June 25 (obsID 6933), and October 1 (obsID 6932).
Our optical data of the system consist of two pointings of the Large
Format Camera (LFC) on the Palomar 5m telescope and 17 pointings of
the higher-resolution Advanced Camera for Surveys (ACS) on the Hubble
Space Telescope (HST). Details of these observations and subsequent
data reduction are presented in Gal et al. (2005AJ....129.1827G 2005AJ....129.1827G,
2008ApJ...684..933G 2008ApJ...684..933G) and D. D. Kocevski et al. (2009ApJ...700..901K 2009ApJ...700..901K).
The Cl1604 supercluster has been extensively mapped in litterature
using the Low-Resolution Imaging Spectrograph (LRIS) and the Deep
Imaging Multi-Object Spectrograph (DEIMOS) on the Keck 10m telescope.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 118 161 Catalog of the 161 X-ray sources detected in the
field of the Cl1604 supercluster with a 3σ
significance in at least one X-ray band
table4.dat 84 125 Catalog of the 112 X-ray sources matched to
optical counterparts
--------------------------------------------------------------------------------
See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
J/AJ/116/560 : Cl J0023+0423 and Cl J1604+4304 spectroscopy (Postman+ 1998)
J/AJ/116/584 : Cl J0023+0423 and Cl J1604+4304 morphology (Lubin+ 1998)
J/AJ/122/2222 : Superclusters of Abell and X-ray clusters (Einasto+, 2001)
J/ApJS/150/19 : ChaMP. I. First X-ray source catalog (Kim+, 2004)
J/PASJ/58/931 : X-ray sources in A194 and A1060 (Hudaverdi+, 2006)
J/A+A/462/449 : Chandra point-source counts in galaxy cluster (Branchesi+,
2007)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Name Source name (<[KLG2009] JHHMMSS.s+DDMMSS> in
Simbad)
18- 19 I2 h RAh Hour of Right Ascension (J2000)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 27 F4.1 s RAs Second of Right Ascension (J2000)
29 A1 --- DE- Sign of Declination (J2000)
30- 31 I2 deg DEd Degree of Declination (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of Declination (J2000)
41- 45 F5.2 arcsec ePos Positional uncertainty
47- 51 F5.1 ct Scts Aperture corrected net soft (0.5-2keV) counts
53- 57 F5.1 ct Hcts Aperture corrected net hard (2-8keV) counts
59- 63 F5.1 ct Fcts Aperture corrected net full (0.5-8keV) counts
65- 72 E8.2 mW/m2 SFlux Soft (0.5-2keV) flux in units of erg/s/cm2
74- 81 E8.2 mW/m2 HFlux Hard (2-8keV) flux in units of erg/s/cm2
83- 90 E8.2 mW/m2 FFlux Full (0.5-8keV) flux in units of erg/s/cm2
92- 96 F5.1 --- SSig Soft (0.5-2keV) detection significance (1)
98-102 F5.1 --- HSig Soft (2-8keV) detection significance (1)
104-108 F5.1 --- FSig Soft (0.5-8keV) detection significance (1)
110-114 F5.2 --- HR [-1,1] Hardness ratio (2)
116-118 A3 --- Flag [SFH ] Wavdetect band: S(0.5-2keV), H(2-8keV)
and F(0.5-8keV)
--------------------------------------------------------------------------------
Note (1): As determined by aperture photometry. Detection significances
measured as: Sig=Cts(net)/(1.0+(0.75+Cts(bg))0.5)
Note (2): Measured as HR=(H-S)/(H+S) where H and S are the net counts in
the hard and soft bands, respectively.
--------------------------------------------------------------------------------
Byte-by-byte Description of file:table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Name Source name (<[KLG2009] JHHMMSS.s+DDMMSS> in
Simbad) (sometimes several lines for one source)
18- 19 I2 h RAXh X-ray centroid Hour of Right Ascension (J2000)
21- 22 I2 min RAXm X-ray centroid Minute of Right Ascension (J2000)
24- 27 F4.1 s RAXs X-ray centroid Second of Right Ascension (J2000)
29 A1 --- DEX- X-ray centroid Sign of Declination (J2000)
30- 31 I2 deg DEXd X-ray centroid Degree of Declination (J2000)
33- 34 I2 arcmin DEXm X-ray centroid Arcminute of Declination (J2000)
36- 39 F4.1 arcsec DEXs X-ray centroid Arcsecond of Declination (J2000)
41- 42 I2 h RAOh Optical centroid Hour of Right Ascension (J2000)
44- 45 I2 min RAOm Optical centroid Minute of Right Ascension (J2000)
47- 50 F4.1 s RAOs Optical centroid Second of Right Ascension (J2000)
52 A1 --- DEO- Optical centroid Sign of Declination (J2000)
53- 54 I2 deg DEOd Optical centroid Degree of Declination (J2000)
56- 57 I2 arcmin DEOm Optical centroid Arcminute of Declination (J2000)
59- 62 F4.1 arcsec DEOs Optical centroid Arcsecond of Declination (J2000)
64- 68 F5.3 --- Sigma Probability X-ray source has an optical
counterpart
70- 74 F5.3 --- Pgen Probability optical source is a genuine
counterpart
76- 81 F6.3 --- z ? Spectroscopic redshift
83- 84 I2 --- q_z [-1/4]? Spectroscopic redshift quality flag (1)
--------------------------------------------------------------------------------
Note (1): Quality flags as follows:
1 = a secure redshift could not be determined due to poor signal, lack of
features or reduction artifacts
2 = a redshift obtained from either a single feature or two marginally
detected features
3 = a redshift derived from at least one secure and one marginal feature
4 = a redshift obtained from several high signal-to-noise features
-1 = source securely identified as a star
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Feb-2011