J/MNRAS/348/857 Radio-loud QSOs at z∼4 (Holt+, 2004)
A sample of radio-loud QSOs at redshift ∼4.
Holt J., Benn C.R., Vigotti M., Pedani M., Carballo R.,
Gonzalez-serrano J.I., Mack K.-H., Garcia B.
<Mon. Not. R. Astron. Soc., 348, 857-865 (2004)>
=2004MNRAS.348..857H 2004MNRAS.348..857H
ADC_Keywords: QSOs ; Redshifts ; Photometry ; Radio lines ; Spectroscopy
Keywords: quasars: emission lines - quasars: general - early Universe -
radio continuum: galaxies
Abstract:
We obtained spectra of 60 red, star-like objects (mE<18.8) identified
with FIRST radio sources, S1.4GHz>1mJy. Eight are quasi-stellar
objects (QSOs) with redshift z>3.6. Combined with our earlier pilot
search, our sample of 121 candidates yields a total of 18 z>3.6 QSOs
(10 of these with z>4.0). 8 per cent of candidates with
S1.4GHz<10mJy and 37 per cent of candidates with S1.4GHz>10mJy are
QSOs with z>3.6. The surface density of mE<18.8, S1.4GHz>1mJy, z>4
QSOs is 0.003deg-2. This is currently the only well-defined sample
of radio-loud QSOs at z∼4 selected independently of radio spectral
index. The QSOs are highly luminous in the optical (eight have
MB<28, q0=0.5, H0=50km/s/Mpc). The SEDs are as varied as those
seen in optical searches for high-redshift QSOs, but the fraction of
objects with weak (strongly self-absorbed) Ly emission is marginally
higher (3 out of 18) than for high-redshift QSOs from SDSS (5 out of
96).
Description:
Observations of 54 of the 194 candidates were reported in Paper I,
Benn et al., 2002MNRAS.329..221B 2002MNRAS.329..221B. The 55th object reported there,
1349+38, is actually detected on the Minnesota APS scan of the POSS-I
blue plate (i.e. it is not red), and thus does not meet selection
criterion (red also in the Minnesota APS (Pennington et al. catalogue
of the POSS-I plates, 1993PASP..105..521P 1993PASP..105..521P). Spectra were obtained of
60 more candidates using the IDS spectrograph on the Isaac Newton
Telescope during near-photometric nights (occasional light cirrus) in
2001 May. Some of the 194 candidates were imaged through a Harris R
filter with the 1.0-m Jacobus Kapteyn Telescope (JKT) in service time,
in order to identify extended objects. Spectra were later obtained of
most of these candidates at the Isaac Newton Telescope (INT), but the
'G' (galaxy) classifications of four objects in Table 2 are based on
JKT imaging alone. The 13 z>3.6 QSOs with S1.4GHz>3mJy were observed
at 4.85 and 10GHz, with the Effelsberg radio telescope, during the
night of 2002 January 13.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 174 20 High-redshift radio QSOs in FIRST (VIII/71)
table2.dat 116 59 Candidates which are not z>3.6 QSOs
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See also:
VIII/71 : The FIRST Survey Catalog, Version 03Apr11 (Becker+ 2003)
J/ApJS/143/1 : FIRST-APM Source Catalog (McMahon+, 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Sample [ABC] Sample designation (1)
3- 4 I2 h RAh Optical right ascension (J2000.0)
6- 7 I2 min RAm Optical right ascension (J2000.0)
9- 13 F5.2 s RAs Optical right ascension (J2000.0)
15 A1 --- DE- Declination sign (J2000.0)
16- 17 I2 deg DEd Declination (J2000.0)
19- 20 I2 arcmin DEm Declination (J2000.0)
22- 25 F4.1 arcsec DEs Declination (J2000.0)
27- 30 F4.1 mJy S1.4GHz ? FIRST 1.4GHz flux density (integrated for
S1.4GHz>10mJy, otherwise peak)
32- 35 F4.1 mJy S4.85GHz ? Integrated Effelsberg 4.85GHz flux density
37- 40 F4.1 mJy S10.6GHz ? Integrated Effelsberg 10.6GHz flux density
42- 46 F5.2 --- Sp+Index ? Radio spectral index alpha
48- 52 F5.2 [W/Hz] logLR Radio luminosity (2)
54- 56 F3.1 arcsec dR-O Radio-optical position difference
58- 61 F4.1 mag Emag APM POSS-I E magnitude
63 A1 --- l_O-E Limit flag on O-E
64- 66 F3.1 mag O-E APM POSS-I O-E colour
68- 71 F4.1 mag Rmag ? JKT (Jacobus Kapteyn Telescope) R magnitude
73- 76 F4.1 mag Imag ? JKT (Jacobus Kapteyn Telescope) I magnitude
78- 82 F5.3 --- z Redshift
84- 88 F5.3 --- e_z rms error on redshift
90 A1 --- l_EWLya+NV Limit flag on EWLya+NV
91- 93 I3 0.1nm EWLya+NV ? Approximate rest-frame Lyα+NV
equivalent width, ±30%
94 A1 --- u_EWLya+NV [?] Uncertainty flag on EWLya+NV
96- 99 F4.2 --- DA Continuum decrement across Lyα line
(Section 4.1.2 of the paper)
101-174 A74 --- Notes Notes
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Note (1): Samples:
A: z>3.6 QSOs with O-E>3, reported in this paper
B: z>3.6 QSOs with O-E>3, reported by Benn et al. (2002MNRAS.329..221B 2002MNRAS.329..221B)
C: z>3 QSOs with O-E<3 (i.e. not included in the sample of 121
candidates) discovered during the INT observations.
Note (2): Assuming H0=50km/s/Mpc, q0=0.5, as used throughout
in this paper, and assuming radio spectral index α=-0.3,
as used by Vigotti et al., 2003ApJ...591...43V 2003ApJ...591...43V).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1 A1 --- Sample [QS] Samples (1)
3- 4 I2 h RAh Optical right ascension (J2000.0)
6- 7 I2 min RAm Optical right ascension (J2000.0)
9- 13 F5.2 s RAs Optical right ascension (J2000.0)
15 A1 --- DE- Declination sign (J2000.0)
16- 17 I2 deg DEd Declination (J2000.0)
19- 20 I2 arcmin DEm Declination (J2000.0)
22- 25 F4.1 arcsec DEs Declination (J2000.0)
27- 31 F5.1 mJy S1.4GHz ? FIRST 1.4GHz flux density (integrated, for
S1.4GHz>10mJy, otherwise peak)
33- 35 F3.1 arcsec dR-O Radio-optical position difference
37- 40 F4.1 mag Emag APM POSS-I E magnitude
42 A1 --- l_O-E Limit flag on O-E
43- 45 F3.1 mag O-E APM POSS-I O-E colour
47 A1 --- Type [QGS?*] Type of object
(Q = QSO, G = Galaxy, ? = probable galaxy,
* = star, S not explained)
49- 54 F6.4 --- z ? Redshift
56- 61 F6.4 --- e_z ? rms error on redshift
63-136 A74 --- Notes Notes
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Note (1): Samples:
Q: Low-redshift QSOs and galaxies ('?'= probable galaxy)
S: Stars
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History:
From electronic version of the journal
References:
Benn et al., Paper I 2002MNRAS.329..221B 2002MNRAS.329..221B
(End) James Marcout, Patricia Bauer [CDS] 30-Mar-2004