J/MNRAS/436/997 Luminous radio galaxies & type-2 quasars (Ramos Almeida+, 2013)
The environments of luminous radio galaxies and type-2 quasars.
Ramos Almeida C., Bessiere P.S., Tadhunter C.N., Inskip K.J., Morganti R.,
Dicken D., Gonzalez-Serrano J.I., Holt J.
<Mon. Not. R. Astron. Soc., 436, 997-1016 (2013)>
=2013MNRAS.436..997R 2013MNRAS.436..997R (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Active gal. nuclei
Keywords: galaxies: active - galaxies: elliptical and lenticular, cD -
galaxies: evolution - galaxies: interactions - galaxies: nuclei
Abstract:
We present the results of a comparison between the environments of (1)
a complete sample of 46 southern 2-Jy radio galaxies at intermediate
redshifts (0.05<z<0.7), (2) a complete sample of 20 radio-quiet type-2
quasars (0.3≤z≤0.41), and (3) a control sample of 107 quiescent
early-type galaxies at 0.2≤z<0.7 in the Extended Groth Strip. The
environments have been quantified using angular clustering amplitudes
(Bgq) derived from deep optical imaging data. Based on these
comparisons, we discuss the role of the environment in the triggering
of powerful radio-loud and radio-quiet quasars. When we compare the
Bgq distributions of the type-2 quasars and quiescent early-type
galaxies, we find no significant difference between them. This is
consistent with the radio-quiet quasar phase being a short-lived but
ubiquitous stage in the formation of all massive early-type galaxies.
On the other hand, powerful radio galaxies are in denser environments
than the quiescent population, and this difference between
distributions of Bgq is significant at the 3σ level. This result
supports a physical origin of radio loudness, with high-density gas
environments favouring the transformation of active galactic nucleus
(AGN) power into radio luminosity, or alternatively, affecting the
properties of the supermassive black holes themselves. Finally,
focusing on the radio-loud sources only, we find that the clustering
of weak-line radio galaxies (WLRGs) is higher than the strong-line
radio galaxies (SLRGs), constituting a 3σ result. 82 percent of
the 2-Jy WLRGs are in clusters, according to our definition
(Bgq≳400), versus only 31 percent of the SLRGs.
Description:
Our sample of 46 PRGs was imaged with the Gemini Multi-Object
Spectrograph-South (GMOS-S) on the 8.1-m Gemini South telescope at
Cerro Pachon under good seeing conditions [median seeing full width
at half-maximum (FWHM) of 0.8-arcsec, ranging from 0.4 to
1.1-arcsec.
Deep optical imaging data for the 20 objects were obtained using
GMOS-S and exactly the same instrumental configuration as for the 2-Jy
sample. The observations were carried out in queue mode between 2009
August and 2011 September in good seeing conditions, with a median
value of FWHM=0.8-arcsec, ranging between 0.5 and 1.1-arcsec.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 82 46 Individual spatial clustering amplitudes of the
2-Jy PRGs sample
table5.dat 70 20 Individual spatial clustering amplitudes of the
the type-2 quasars studied in
Bessiere et al. (2012MNRAS.426..276B 2012MNRAS.426..276B)
tablec1.dat 70 107 Individual spatial clustering amplitudes of the
107 early-type galaxies in the EGS sample
tablec2.dat 70 51 Individual spatial clustering amplitudes of the
51 early-type galaxies in the EGS* sample
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See also:
J/MNRAS/419/687 : Morphology of luminous radio-loud AGN (Ramos Almeida+, 2012)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- PKS PKS name (HHMM+DD)
9- 13 F5.3 --- z Redshift
15- 18 A4 --- Opt Optical classification of the galaxies from
Dicken et al. (2008ApJ...678..712D 2008ApJ...678..712D)
20- 23 A4 --- Rad Radio morphology of the galaxies from
Dicken et al. (2008ApJ...678..712D 2008ApJ...678..712D)
25- 26 I2 --- Nt Total number of galaxies within a r170kpc
radius, excluding the target
28- 31 F4.2 --- Nb Number of background galaxies within the same radius
33- 36 I4 --- Bgq ?=- Angular clustering amplitude
38- 41 F4.2 --- Nbav Average number of background galaxies
43- 46 F4.2 --- sigma Standard deviation of the number of background
galaxies calculated using all the dedicated
offset fields in a given filter (Nbav and Nbmed)
48- 51 I4 --- Bgqav Average angular clustering amplitude
53- 55 I3 --- e_Bgqav rms uncertainty on Bgqav
57- 60 F4.2 --- Nbmed Median number of background galaxies
62- 65 I4 --- Bgqmed ?=- Median angular clustering amplitude
67- 82 A16 --- Morph Morphology (G1)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Name (JHHMM+DD)
10- 14 F5.3 --- z Redshift
16- 17 I2 --- Nt Total number of galaxies within a r170kpc
radius, excluding the target
19- 22 F4.2 --- Nb ?=- Number of background galaxies within the
same radius
24- 27 I4 --- Bgq ?=- Angular clustering amplitude
29- 32 F4.2 --- Nbav Average number of background galaxies
34- 37 F4.2 --- sigma Standard deviation of the number of background
galaxies calculated using all the dedicated
offset fields in a given filter (Nbav and Nbmed)
39- 42 I4 --- Bgqav Average angular clustering amplitude
44- 46 I3 --- e_Bgqav rms uncertainty on Bgqav
48- 51 F4.2 --- Nbmed Median number of background galaxies
53- 56 I4 --- Bgqmed Median angular clustering amplitude
58- 77 A20 --- Morph Morphology (G1)
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Byte-by-byte Description of file: tablec1.dat tablec2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IRAC IRAC ID
10- 13 F4.2 --- zph Photometric redshift
16 I1 --- Nt Total number of galaxies within a r170kpc
radius, excluding the target
18- 21 F4.2 --- Nb Number of background galaxies within the same radius
23- 26 I4 --- Bgq Angular clustering amplitude
28- 31 F4.2 --- Nbav Average number of background galaxies
33- 36 F4.2 --- sigma Standard deviation of the number of background
galaxies calculated using all the dedicated
offset fields in a given filter (Nbav and Nbmed)
38- 41 I4 --- Bgqav Average angular clustering amplitude
43- 45 I3 --- e_Bgqav rms uncertainty on Bgqav
47- 50 F4.2 --- Nbmed Median number of background galaxies
52- 55 I4 --- Bgqmed Median angular clustering amplitude
57- 76 A20 --- Morph Morphology (G1)
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Global notes:
Note (G1): Morphological classification in Ramos Almeida et al.
(2011MNRAS.410.1550R 2011MNRAS.410.1550R, 2Jy sample), 2012, Cat. J/MNRAS/419/687 (EGS sample) and
Bessiere et al. (2012MNRAS.426..276B 2012MNRAS.426..276B, type-2 quasars) as follows:
T = tail
F = fan
B = bridge
S = shell
D = dust feature
2N = double nucleus
3N = triple nucleus
A = amorphous halo
I = irregular feature
J = jet
Brackets indicate uncertain identification of the feature.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-Apr-2016