J/ApJ/859/38 HST grism obs. of CARLA galaxy cluster candidates (Noirot+, 2018)
HST grism confirmation of 16 structures at 1.4 < z < 2.8 from the Clusters
Around Radio-Loud AGN (CARLA) Survey.
Noirot G., Stern D., Mei S., Wylezalek D., Cooke E.A., De Breuck C.,
Galametz A., Hatch N.A., Vernet J., Brodwin M., Eisenhardt P.,
Gonzalez A.H., Jarvis M., Rettura A., Seymour N., Stanford S.A.
<Astrophys. J., 859, 38 (2018)>
=2018ApJ...859...38N 2018ApJ...859...38N
ADC_Keywords: Clusters, galaxy; Active gal. nuclei; Photometry, HST;
Spectra, infrared; Redshifts; Surveys
Keywords: galaxies: clusters: general ; galaxies: high-redshift
Abstract:
We report spectroscopic results from our 40-orbit Hubble Space
Telescope slitless grism spectroscopy program observing the 20 densest
Clusters Around Radio-Loud AGN (CARLA) candidate galaxy clusters at
1.4<z<2.8. These candidate rich structures, among the richest and most
distant known, were identified on the basis of [3.6]-[4.5] color from
a 408hr multi-cycle Spitzer program targeting 420 distant radio-loud
AGN. We report the spectroscopic confirmation of 16 distant structures
at 1.4<z<2.8 associated with the targeted powerful high-redshift
radio-loud AGN. We also report the serendipitous discovery and
spectroscopic confirmation of seven additional structures at
0.87<z<2.12 not associated with the targeted radio-loud AGN. We find
that 1010-1011M☉ member galaxies of our confirmed CARLA
structures form significantly fewer stars than their field
counterparts at all redshifts within 1.4≤z≤2. We also observe higher
star-forming activity in the structure cores up to z=2, finding
similar trends as cluster surveys at slightly lower redshifts
(1.0<z<1.5). By design, our efficient strategy of obtaining just two
grism orbits per field only obtains spectroscopic confirmation of
emission line galaxies. Deeper spectroscopy will be required to study
the population of evolved, massive galaxies in these (forming)
clusters. Lacking multi-band coverage of the fields, we adopt a very
conservative approach of calling all confirmations "structures,"
although we note that a number of features are consistent with some of
them being bona fide galaxy clusters. Together this survey represents
a unique and large homogenous sample of spectroscopically confirmed
structures at high redshifts, potentially more than doubling the
census of confirmed, massive clusters at z>1.4.
Description:
The Clusters Around Radio-Loud AGN (CARLA) project has used 408hr of
Spitzer time to image 420 high-redshift radio-loud AGN, searching for
associated galaxy clusters (Wylezalek+ 2013, J/ApJ/769/79 and 2014,
J/ApJ/786/17). With IRAC exposures of ∼1hr per field, CARLA reaches
10σ depths of m*+2 out to z≳2.
Our HST program consists of WFC3/F140W imaging and WFC3/G141 grism
spectroscopy of the 20 densest CARLA cluster candidates, selected from
420 radio-loud AGN at z>1.3 observed in our Spitzer program
(Wylezalek+ 2013, J/ApJ/769/79).
A total of 10 fields are associated with high-redshift radio galaxies
(HzRGs, type-2 radio-loud AGN), and the other 10 with radio-loud
quasars (RLQs, type-1 RLAGN). The 20 fields were observed between 2014
October and 2016 April (Program ID: 13740).
The G141 grism covers the wavelength range 1.08-1.70um with a
throughput >10% at low spectral resolution, R=130.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 49 41 HST WFC3 observations
table2.dat 67 27 Clusters Around Radio-Loud AGN (CARLA) HST results
table3.dat 168 707 Spectroscopic catalog content
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
VIII/2 : Molonglo Reference Catalog of Radio Sources (Large+ 1981)
J/AJ/127/2002 : Star Formation Rate of NFGS galaxies (Kewley+, 2004)
J/ApJ/657/738 : SDF galaxies multi-photometry (Ly+, 2007)
J/MNRAS/383/581 : Broad-line Balmer decrements in blue AGN (Dong+, 2008)
J/ApJ/684/905 : IRAC Shallow Survey z>1 galaxy clusters (Eisenhardt+, 2008)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/ApJ/746/85 : THe HST Cluster Supernova Survey. V. (Suzuki+, 2012)
J/A+A/550/A114 : Integrated spectroscopy of HRS galaxies (Boselli+, 2013)
J/A+A/559/A2 : Redshifts in the surroundings of MRC0156-252 (Galametz+, 2013)
J/ApJ/763/127 : Galaxy clusters discovered in SPT survey (Reichardt+, 2013)
J/ApJ/769/79 : Spitzer obs. of radio-loud AGNs (CARLA) (Wylezalek+, 2013)
J/ApJS/213/25 : WISE Massive & Distant Clusters. II. (Stanford+, 2014)
J/ApJ/786/17 : Luminosity functions for 1.3<z<3.2 galaxies (Wylezalek+, 2014)
J/ApJS/216/27 : Galaxy clusters discovered in the SPT-SZ survey (Bleem+, 2015)
J/ApJS/225/27 : 3D-HST Survey: grism spectra master catalog (Momcheva+, 2016)
J/ApJ/844/78 : High-redshift COBRA survey: IRAC obs. (Paterno-Mahler+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 A20 --- Field Field identifier
22- 32 A11 "Y/M/D" Date UT date of observation
34 A1 --- f_Date Flag on Date (1)
37- 40 I4 deg PA [-160/173] Position angle; east of north
42- 44 I3 s Exp1 [462/537] HST/WFC3 F140W exposure time
45 A1 --- --- [/]
46- 49 I4 s Exp2 [2012/2262] HST/WFC3 G141 grism exposure time
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Note (1):
b = Failed. Re-observed on UT 2015 November 22.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- f_Field [csu] Flag on Field (1)
3- 23 A21 --- Field Field identifier
25- 28 F4.2 --- sigIRAC [4/8]? Overdensity significance of color-selected
sources above the field value
(Wylezalek+ 2014, J/ApJ/786/17) σIRAC
30- 34 F5.3 --- zRLAGN [1.3/2.8]? Radio loud AGN redshift
36- 40 F5.3 --- zClavg [0.8/2.9] Mean redshift of structure members
41 A1 --- u_zClavg [)] Uncertainty flag on zClavg (2)
43- 47 F5.3 --- zClmed [0.8/2.9] Median redshift of structure members
48 A1 --- u_zClmed [)] Uncertainty flag on zClmed (2)
50 A1 --- u_HSTcl [(] Uncertainty flag on HSTcl (2)
51- 52 I2 --- HSTcl [2/14] Number of HST/F140W confirmed structure
members
53 A1 --- --- [/]
54- 55 I2 --- HSTtot [23/51] Total number of HST sources for which we
measure a redshift
57 A1 --- u_IRACcl [(] Uncertainty flag on IRACcl (2)
58- 58 I1 --- IRACcl [0/9] Number of Spitzer/IRAC confirmed structure
members
59 A1 --- --- [/]
60- 61 I2 --- IRACtot [8/28] Total number of Spitzer/IRAC sources for
which we measure a redshift
63 A1 --- u_Colcl [(] Uncertainty flag on Colcl (2)
64- 64 I1 --- Colcl [0/8] Number of Spitzer/IRAC [3.6]-[4.5]>-0.1
color-selected confirmed structure members
65 A1 --- --- [/]
66- 67 I2 --- Coltot [7/18] Total number of Spitzer/IRAC color-selected
sources for which we measure a redshift
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Note (1): Code as follows:
c = Confirmed CARLA structures
u = Unconfirmed CARLA structures
s = Serendipitous discoveries
Note (2): For unconfirmed structures, mean and median redshifts and source
numbers are based on the few confirmed sources at the RLAGN redshifts.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Field Field identifier (1)
22- 26 I5 --- ID [2/90000] Unique source identifier from Field
28- 40 F13.9 deg RAdeg [19.2/359] Right Ascension (J2000)
42- 57 F16.12 deg DEdeg [-29.1/63.2] Declination (J2000)
59- 64 F6.3 mag F140Wmag [17.1/26.5] HST/WFC3 F140W filter
AB magnitude
67- 71 F5.3 mag e_F140Wmag [0.001/0.3] Uncertainty in F140Wmag
74- 78 F5.3 --- z [0.3/2.9] Redshift
80- 84 F5.3 --- e_z [0.002/0.02]? Uncertainty in z
86- 87 A2 --- q_z Quality of z (A=very secure) (see section 4.1)
89- 97 E9.4 mW/m2 FHa [1e-17/7e-14]? Hα flux; erg/s/cm2 (2)
99-107 E9.4 mW/m2 e_FHa [7e-18/3e-15]? Uncertainty in FHa
110-118 E9.4 mW/m2 FHb [1e-17/2e-14]? Hβ flux; erg/s/cm2
120-128 E9.4 mW/m2 e_FHb [1e-17/4e-15]? Uncertainty in FHb
130-138 E9.4 mW/m2 FO3 [7e-18/2e-14]? The [OIII]5007Å flux;
erg/s/cm2
140-148 E9.4 mW/m2 e_FO3 [3e-18/3e-15]? Uncertainty in FO3
150-158 E9.4 mW/m2 FO2 [1e-17/4e-16]? The [OII]3727+3729Å flux;
erg/s/cm2
160-168 E9.4 mW/m2 e_FO2 [1e-17/10e-17]? Uncertainty in FO2
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Note (1): CARLA names for all fields where a CARLA confirmed structure is
present. Target RLAGN name otherwise, except for CARLA-Ser J1317+3925
(only serendipitous structure within a field with no confirmed
CARLA structure).
Note (2): Fluxes include [N II] contributions.
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Nomenclature note:
Sources in Table 3 are <[NSM2018] {Field} {ID}> in Simbad.
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Apr-2019