J/ApJ/786/17 Luminosity functions for 1.3<z<3.2 galaxies (Wylezalek+, 2014)
The galaxy cluster mid-infrared luminosity function at 1.3<z<3.2.
Wylezalek D., Vernet J., De Breuck C., Stern D., Brodwin M., Galametz A.,
Gonzalez A.H., Jarvis M., Hatch N., Seymour N., Stanford S.A.
<Astrophys. J., 786, 17 (2014)>
=2014ApJ...786...17W 2014ApJ...786...17W (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; Galaxies, radio
Keywords: galaxies: active - galaxies: clusters: general - galaxies: evolution -
galaxies: formation - galaxies: high-redshift -
galaxies: luminosity function, mass function - techniques: photometric
Abstract:
We present 4.5 µm luminosity functions for galaxies identified in
178 candidate galaxy clusters at 1.3<z<3.2. The clusters were
identified as Spitzer/Infrared Array Camera (IRAC) color-selected
overdensities in the Clusters Around Radio-Loud AGN project, which
imaged 420 powerful radio-loud active galactic nuclei (RLAGNs) at z>1.3.
The luminosity functions are derived for different redshift and
richness bins, and the IRAC imaging reaches depths of m*+2, allowing
us to measure the faint end slopes of the luminosity functions. We
find that α=-1 describes the luminosity function very well in
all redshift bins and does not evolve significantly. This provides
evidence that the rate at which the low mass galaxy population grows
through star formation gets quenched and is replenished by in-falling
field galaxies does not have a major net effect on the shape of the
luminosity function. Our measurements for m* are consistent with
passive evolution models and high formation redshifts (zf∼3). We
find a slight trend toward fainter m* for the richest clusters,
implying that the most massive clusters in our sample could contain
older stellar populations, yet another example of cosmic downsizing.
Modeling shows that a contribution of a star-forming population of up
to 40% cannot be ruled out. This value, found from our targeted
survey, is significantly lower than the values found for slightly
lower redshift, z∼1, clusters found in wide-field surveys. The
results are consistent with cosmic downsizing, as the clusters studied
here were all found in the vicinity of RLAGNs - which have proven to be
preferentially located in massive dark matter halos in the richest
environments at high redshift - and they may therefore be older and
more evolved systems than the general protocluster population.
Description:
The cluster candidates studied in this paper were identified as IRAC
color-selected galaxy overdensities in the fields of CARLA RLAGN. In
order to isolate galaxy cluster candidates, we first identify
high-redshift sources (z>1.3) by applying the color cut [3.6]-[4.5]≥-0.1
(e.g., Papovich 2008ApJ...676..206P 2008ApJ...676..206P). This color selection has proven
to be very efficient at identifying high-redshift galaxies independent
of their evolutionary stage. A negative k-correction, caused by the
1.6 um bump that enters the IRAC bands at z∼1, leads to an almost
constant IRAC2 apparent magnitude at z>1.3 and a red [3.6]-[4.5] color
(Stern et al. 2005ApJ...631..163S 2005ApJ...631..163S; Eisenhardt et al. 2008, J/ApJ/684/905;
Wylezalek et al. 2013, J/ApJ/769/79). We apply a counts-in-cells
analysis to such color-selected IRAC sources, which we simply refer to
as IRAC-selected sources, to identify overdense fields.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 66 420 The CARLA sample (in RA order)
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See also:
J/A+A/343/93 : Local radio luminosity function of galaxies. II.
(Gavazzi+ 1999)
J/ApJ/684/905 : z>1 galaxy clusters from IRAC Shallow Survey
(Eisenhardt+, 2008)
J/ApJ/686/966 : Spitzer-FLS catalog of clusters of galaxies (Muzzin+, 2008)
J/ApJ/769/79 : Spitzer observations of radio-loud AGNs (CARLA)
(Wylezalek+, 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Source identifier
21- 22 I2 h RAh Hour of Right Ascension (J2000)
24- 25 I2 min RAm Minute of Right Ascension (J2000)
27- 31 F5.2 s RAs Second of Right Ascension (J2000)
33 A1 --- DE- Sign of the Declination (J2000)
34- 35 I2 deg DEd Degree of Declination (J2000)
37- 38 I2 arcmin DEm Arcminute of Declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of Declination (J2000)
45- 48 F4.2 --- z Redshift
50- 54 F5.2 [W/Hz] logL500 Log luminosity at 500 MHz
56- 59 F4.1 arcmin-2 Sigma ? Surface density
61 A1 --- f_Sigma [N] Flag on Sigma (1)
63- 66 A4 --- Type Source type (2)
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Note (1): Flag as follows:
N = No surface density available due to field contaminated, e.g. bright stars.
Note (2): Type as follows:
HzRG = High-redshift radio galaxy;
RLQ = Radio-loud quasar.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 16-Jun-2017