J/MNRAS/448/3167 z≳5 AGN in Chandra Deep Field-South (Weigel+, 2015)
The systematic search for z ≳ 5 active galactic nuclei in the
Chandra Deep Field-South.
Weigel A.K., Schawinski K., Treister E., Urry C.M., Koss M.,
Trakhtenbrot B.
<Mon. Not. R. Astron. Soc., 448, 3167-3195 (2015)>
=2015MNRAS.448.3167W 2015MNRAS.448.3167W (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Redshifts ; Photometry, UBV ;
Photometry, infrared ; X-ray sources
Keywords: galaxies: active - galaxies: high-redshift - X-rays: galaxies
Abstract:
We investigate early black hole (BH) growth through the methodical
search for z≳5 active galactic nuclei (AGN) in the Chandra Deep
Field South. We base our search on the Chandra 4-Ms data with flux
limits of 9.1x10-18erg/s/cm2 (soft, 0.5-2keV) and
5.5x10-17erg/s/cm2 (hard, 2-8keV). At z∼5, this corresponds to
luminosities as low as ∼1042erg/s/cm2 (∼1043erg/s) in the soft
(hard) band and should allow us to detect Compton-thin AGN with
MBH>107M☉ and Eddington ratios >0.1. Our field (0.03deg2)
contains over 600 z∼5 Lyman Break Galaxies. Based on lower redshift
relations, we would expect ∼20 of them to host AGN. After combining
the Chandra data with Great Observatories Origins Deep Survey
(GOODS)/Advanced Camera for Surveys (ACS), CANDELS/Wide Field Camera 3
and Spitzer/Infrared Array Camera data, the sample consists of 58
high-redshift candidates. We run a photometric redshift code, stack
the GOODS/ACS data, apply colour criteria and the Lyman Break
Technique and use the X-ray Hardness Ratio. We combine our tests and
using additional data find that all sources are most likely at low
redshift. We also find five X-ray sources without a counterpart in the
optical or infrared which might be spurious detections. We conclude
that our field does not contain any convincing z≳5 AGN. Explanations
for this result include a low BH occupation fraction, a low AGN
fraction, short, super-Eddington growth modes, BH growth through BH-BH
mergers or in optically faint galaxies. By searching for z≳5 AGN, we
are setting the foundation for constraining early BH growth and seed
formation scenarios.
Description:
The Chandra 4-Ms source catalogue by Xue et al. (2011, Cat.
J/ApJS/195/10) is the starting point of this work. It contains 740
sources and provides counts and observed frame fluxes in the soft
(0.5-2keV), hard (2-8keV) and full (0.5-8keV) band. All object IDs
used in this work refer to the source numbers listed in the Xue et al.
(2011, Cat. J/ApJS/195/10) Chandra 4-Ms catalogue. We make use of
Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) data
from the Great Observatories Origins Deep Survey South (GOODS-south)
in the optical wavelength range. We use catalogues and images for
filters F435W (B), F606W (V), F775W (i) and 850LP (z) from the second
GOODS/ACS data release (v2.0; Giavalisco et al., 2004, Cat. II/261).
We use Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
(CANDELS) Wide Field Camera 3 (WFC3)/infrared data from the first data
release (DR1, v1.0) for passbands F105W (Y), F125W (J) and F160W (H)
(Grogin et al., 2011ApJS..197...35G 2011ApJS..197...35G; Koekemoer et al.,
2011ApJS..197...36K 2011ApJS..197...36K). To determine which objects are red, dusty,
low-redshift interlopers, we also include the 3.6 and 4.5 micron
Spitzer Infrared Array Camera (IRAC) channels. We use SIMPLE image
data from the DR1 (van Dokkum et al., 2005, Spitzer Proposal,
2005.20708) and the first version of the extended SIMPLE catalogue by
Damen et al. (2011, Cat. J/ApJ/727/1).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 79 58 Overview over the redshift estimates that we
gained for each object in the course of
this analysis
tablea4.dat 76 58 HR values, X-ray counts, errors on the X-ray
counts and signal-to-noise ratio values for
the main sample
tablea5.dat 125 58 Flux densities for our 58 sample sources,
part 1/2
tablea6.dat 125 58 Flux densities for our 58 sample sources,
part 2/2
tablea7.dat 89 58 Magnitude values for our 58 sample sources,
part 1/2
tablea8.dat 86 58 Magnitude values for our 58 sample sources,
part 2/2
--------------------------------------------------------------------------------
See also:
J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)
J/ApJ/727/1 : IRAC/MUSYC SIMPLE survey (Damen+, 2011)
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ID [*] Note on ID (G1)
3- 5 I3 --- ID Identification number
7- 13 F7.4 deg RAdeg Chandra right ascension (J2000)
15- 22 F8.4 deg DEdeg Chandra declination (J2000)
24- 30 F7.4 deg RAHdeg Chandra right ascension (J2000)
32- 39 F8.4 deg DEHdeg Chandra declination (J2000)
41 A1 --- Vis Visual redshift estimate (1)
43 A1 --- Stack Stacking redshift estimate (1)
45 I1 --- Col Colour criteria redshift estimate (1)
47 A1 --- l_HR [lu] Limit flag on HR
(l for lower limit, u for upper limit)
48- 52 F5.2 --- HR Hardness ratio
54- 57 F4.2 --- e_HR ?=- rms uncertainty on HR
59- 63 F5.2 --- zph Photometric redshift
65- 68 F4.2 --- E_zph Error on zph (upper value)
70- 73 F4.2 --- e_zph Error on zph (lower value)
75- 79 F5.2 --- chi2 χ2 value
--------------------------------------------------------------------------------
Note (1): Note that the stacking procedure only gives a redshift indication.
Hence, if '4' is given as the stacking result this corresponds to z≲4,
'7' indicates z≳7.
'0' indicates that a source could not be classified by the corresponding
redshift test.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID Identification number
5 A1 --- l_HR [lu] Limit flag on HD
(l for lower limit, u for upper limit)
6- 10 F5.2 --- HR Hardness ratio (1)
12- 15 F4.2 --- e_HR ? rms uncertainty on HR
17 A1 --- l_Hct [u] u for upper limit
18- 23 F6.2 ct Hct Hard counts (2)
25- 29 F5.2 ct e_Hct ?=-1 rms uncertainty on Hct
31- 35 F5.2 --- HSNR ?=- Hard S/N
37 A1 --- l_Sct [u] u for upper limit
38- 43 F6.2 ct Sct Soft counts (2)
45- 49 F5.2 ct e_Sct ?=-1 rms uncertainty on Sct
51- 55 F5.2 --- SSNR ?=- Soft S/N
57 A1 --- l_Fct [u] u for upper limit
58- 64 F7.2 ct Fct Full counts (2)
66- 70 F5.2 ct e_Fct ?=-1 rms uncertainty on Fct
72- 76 F5.2 --- FSNR ?=- Full S/N
--------------------------------------------------------------------------------
Note (1): The HR values were calculated using equation (4).
Objects for which the HR could not be determined due to an upper limit in
both the Hard and the Soft band, are marked with '---'.
Note (2): The X-ray count values were directly extracted from the Xue et al.
(2011ApJS..195...10, Cat. J/ApJS/195/10) catalogue.
For the errors on the X-ray counts, we give the upper errors given
in the 4-Ms catalogue.
For objects that are not detected, we give an upper limit on the X-ray counts,
set error to -1.00 and mark the signal-to-noise ratio with a dash.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ID [*] Note on ID (G1)
3- 5 I3 --- ID Identification number
7- 15 E9.4 uJy F(B) ?=0 Flux in B band (1)
17- 25 E9.4 uJy e_F(B) ? rms uncertainty on F(B)
27- 35 E9.4 uJy limF(B) ? Sensitivity limit in B when no detection
37- 45 E9.4 uJy F(V) ?=0 Flux in V band (1)
47- 55 E9.4 uJy e_F(V) ? rms uncertainty on F(V)
57- 65 E9.4 uJy limF(v) ? Sensitivity limit in V when no detection
67- 75 E9.4 uJy F(i) ?=0 Flux in i band (1)
77- 85 E9.4 uJy e_F(i) ? rms uncertainty on F(i)
87- 95 E9.4 uJy limF(i) ? Sensitivity limit in i when no detection
97-105 E9.4 uJy F(z) ?=0 Flux in z band (1)
107-115 E9.4 uJy e_F(z) ? rms uncertainty on F(z)
117-125 E9.4 uJy limF(z) ? Sensitivity limit in z when no detection
--------------------------------------------------------------------------------
Note (1): The values given for the 3.6 and 4.5 micron channels correspond to the
1-arcsec aperture radius flux values given in the Damen et al.
(2011ApJ...727....1D 2011ApJ...727....1D, Cat. J/ApJ/727/1) Spitzer catalogue.
For the remaining sources, the Spitzer values could not be included due to
source confusion.
We performed our own aperture photometry for the GOODS/ACS (B, V, i, z) and
CANDELS (Y, J, H) filters.
If an object is not detected in an image (flux < detection threshold), we set
F=0 and limF to the sensitivity limit of the corresponding filter.
If an object's position is not covered by the Y band or we are not using the
Spitzer IRAC data, we mark this with a dash.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ID [*] Note on ID (G1)
3- 5 I3 --- ID Identification number
7- 15 E9.4 uJy F(Y) ? Flux in Y band (2)
17- 25 E9.4 uJy e_F(Y) ? rms uncertainty on F(Y)
27- 35 E9.4 uJy limF(Y) ? Sensitivity limit in Y when no detection
37- 45 E9.4 uJy F(J) ? Flux in J band (2)
47- 55 E9.4 uJy e_F(J) ? rms uncertainty on F(J)
57- 65 E9.4 uJy limF(J) ? Sensitivity limit in J when no detection
67- 75 E9.4 uJy F(H) Flux in H band (2)
77- 85 E9.4 uJy e_F(H) rms uncertainty on F(H)
87- 95 E9.4 uJy F(3.6um) ? Flux in 3.6um band (2)
97-105 E9.4 uJy e_F(3.6um) ? rms uncertainty on F(3.6um)
107-115 E9.4 uJy F(4.5um) ? Flux in 4.5um band (2)
117-125 E9.4 uJy e_F(4.5um) ? rms uncertainty on F(4.5um)
--------------------------------------------------------------------------------
Note (2): The values given for the 3.6 and 4.5 micron channels correspond to the
1.5-arcsec aperture radius flux values given in the Damen et al.
(2011ApJ...727....1D 2011ApJ...727....1D, Cat. J/ApJ/727/1) Spitzer catalogue.
For the remaining sources, the Spitzer values could not be included due to
source confusion.
We performed our own aperture photometry for the GOODS/ACS (B, V, i, z) and
CANDELS (Y, J, H) filters.
If an object is not detected in an image (flux < detection threshold), we set
F=0 and limF to the sensitivity limit of the corresponding filter.
If an object's position is not covered by the Y band or we are not using the
Spitzer IRAC data, we mark this with a dash.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ID [*] Note on ID (G1)
3- 5 I3 --- ID Identification number
8- 13 F6.3 mag Bmag ? B magnitude (AB) (2)
15- 19 F5.3 mag e_Bmag ? rms uncertainty on Bmag
21- 26 F6.3 mag limBmag ? Sensitivity limit in B when no detection
29- 34 F6.3 mag Vmag ? V magnitude (AB) (2)
36- 40 F5.3 mag e_Vmag ? rms uncertainty on Vmag
42- 47 F6.3 mag limVmag ? Sensitivity limit in V when no detection
50- 55 F6.3 mag imag ? i magnitude (AB) (2)
57- 61 F5.3 mag e_imag ? rms uncertainty on imag
63- 68 F6.3 mag limimag ? Sensitivity limit in i when no detection
71- 76 F6.3 mag zmag ? z magnitude (AB) (2)
78- 82 F5.3 mag e_zmag ? rms uncertainty on zmag
84- 89 F6.3 mag limzmag ? Sensitivity limit in z when no detection
--------------------------------------------------------------------------------
Note (2): The values given for the 3.6 and 4.5 micron channels correspond to the
1.5-arcsec aperture radius flux values given in the Damen et al.
(2011ApJ...727....1D 2011ApJ...727....1D, Cat. J/ApJ/727/1) Spitzer catalogue.
For the remaining sources, the Spitzer values could not be included due to
source confusion.
We performed our own aperture photometry for the GOODS/ACS (B, V, i, z) and
CANDELS (Y, J, H) filters.
If an object is not detected in an image (flux < detection threshold), we set
mAB = 0 and limmAB to the sensitivity limit of the corresponding filter.
If an object's position is not covered by the Y band or we are not using the
Spitzer IRAC data, we mark this with a dash.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- n_ID [*] Note on ID (G1)
3- 5 I3 --- ID Identification number
8- 13 F6.3 mag Ymag ? Y magnitude (AB) (2)
15- 19 F5.3 mag e_Ymag ? rms uncertainty on Ymag
21- 26 F6.3 mag limYmag ? Sensitivity limit in Y when no detection
29- 34 F6.3 mag Jmag ? J magnitude (AB) (2)
36- 40 F5.3 mag e_Jmag ? rms uncertainty on Jmag
42- 47 F6.3 mag limJmag ? Sensitivity limit in J when no detection
49- 54 F6.3 mag Hmag ? H magnitude (AB) (2)
56- 60 F5.3 mag e_Hmag ? rms uncertainty on Hmag
62- 67 F6.3 mag [3.6] ? 3.6um magnitude (AB) (2)
69- 73 F5.3 mag e_[3.6] ? rms uncertainty on [3.6]
75- 80 F6.3 mag [4.5] ? 4.5um magnitude (AB) (2)
82- 86 F5.3 mag e_[4.5] ? rms uncertainty on [4.5]
--------------------------------------------------------------------------------
Note (2): The values given for the 3.6 and 4.5 micron channels correspond to the
1.5-arcsec aperture radius flux values given in the Damen et al.
(2011ApJ...727....1D 2011ApJ...727....1D, Cat. J/ApJ/727/1) Spitzer catalogue.
For the remaining sources, the Spitzer values could not be included due to
source confusion.
We performed our own aperture photometry for the GOODS/ACS (B, V, i, z) and
CANDELS (Y, J, H) filters. If an object is not detected in an image
(flux < detection threshold), we set mAB=0 and limmAB to the sensitivity
limit of the corresponding filter.
If an object's position is not covered by the Y band or we are not using the
Spitzer IRAC data, we mark this with a dash.
--------------------------------------------------------------------------------
Global notes:
Note (G1): All photometric redshifts were gained by using GOODS/ACS,
CANDELS and in some cases also Spitzer data (marked with an asterisk).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Sep-2015