J/ApJS/181/548 X-shaped radio sources. II. New redshifts (Cheung+, 2009)
FIRST "Winged" and X-shaped radio source candidates.
II. New redshifts.
Cheung C.C., Healey S.E., Landt H., Kleijn G.V., Jordan A.
<Astrophys. J. Suppl. Ser., 181, 548-556 (2009)>
=2009ApJS..181..548C 2009ApJS..181..548C
ADC_Keywords: Galaxies, radio ; Redshifts ; Spectroscopy ; Spectra, optical
Keywords: galaxies: active - galaxies: distances and redshifts
quasars: general
Abstract:
We reported optical spectroscopic observations of X-shaped radio
sources with the Hobby-Eberly Telescope and Multiple-Mirror Telescope,
focused on the sample of candidates from the FIRST survey presented in
Paper I (Cheung, 2007, Cat. J/AJ/133/2097). A total of 27 redshifts
were successfully obtained, 21 of which are new, including a newly
identified candidate source of this type which is presented here. With
these observations, the sample of candidates from the previous paper
is over 50% spectroscopically identified. Two new broad emission-lined
X-shaped radio sources are revealed, while no emission lines were
detected in about one-third of the observed sources; a detailed study
of the line properties is deferred to a future paper. Finally, to
explore their relation to the Fanaroff-Riley division, the radio
luminosities and host galaxy absolute magnitudes of a
spectroscopically identified sample of 50 X-shaped radio galaxies are
calculated to determine their placement in the Owen-Ledlow plane.
Description:
This paper presents observations with the 9.2m Hobby-Eberly Telescope
(HET) at the McDonald Observatory in 2006 and 2007 under a
queue-observing mode and with the 6.5m Multiple-Mirror Telescope
(MMT) at Mt. Hopkins Observatory in a two-night run in 2007 February.
An observation of one object (J0702+5002) was obtained earlier with
the 2.7m Harlan J. Smith Telescope (HJST) at the McDonald
Observatory.
On the HET, we used the Marcario Low-Resolution Spectrograph (LRS),
with grism G1, a 2" slit, and a Schott GG385 long-pass filter. This
provided broad wavelength coverage (from ∼4000-9200Å) and a
resolution of R∼500. Typically, we obtained 2x300s exposures for the
brightest targets and 2x600s exposures for fainter ones. Eleven total
spectra from the HET are presented here.
The MMT observations utilized the blue-channel spectrograph with a 1"
slit and wavelength range ∼3200-8400Å. The seeing was consistently
at the sub-arcsecond level for all 15 successfully obtained spectra.
The observation of J0702+5002, a candidate X-shaped radio galaxy
identified early on in the work leading up to Paper I
(Cheung 2007, J/AJ/133/2097), was obtained by S. E. Healey in 2005
with the 2.7m HJST, using the Imaging Grism Instrument (IGI) and the
6000Å VPH grism. The redshift was reported in Paper I, and the
spectrum is provided here.
A summary of the observations is presented in Table1.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 52 27 Observation log and measured redshifts
table2.dat 49 50 Parameters of spectroscopically identified
X-shaped radio galaxy sample
sp/* . 27 Individual spectra in FITS format
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See also:
J/AJ/133/2097 : FIRST "Winged" & X-shaped radio source candidates (Cheung 2007)
J/PASP/97/932 : 3CR Source Identifications (Spinrad+, 1985)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Seq Catalog number in Paper I (<[C2007] NNN>
or <[C2007] XNN> in Simbad) (G1)
5- 14 A10 --- [C2007] JHHMM-DDMM (J2000) name
16- 19 F4.1 mag mag Optical magnitude predominantly from
Paper I, see summary in table2.
21- 24 A4 --- Tel Telescope used (2)
26- 35 A10 "Y/M/D" ObsDate Observation date
37- 40 I4 s Exp [600/3300] Total exposure time
42- 46 F5.3 --- z [0.06/0.65] Measured redshift
48- 50 A3 --- n_z Absorption (abs) or emission (em) feature
52 I1 --- f_z [1/5]? Note on redshift (3)
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Note (2): Telescopes as follows:
HET = Hobby-Eberly Telescope (11 occurrences)
HJST = Harlan J. Smith Telescope (1 occurrence)
MMT = Multi-Mirror Telescope (15 occurrences)
Note (3): Note as follows:
1 = redshift previously known, the new spectra tend to be of higher quality
than the previously obtained ones, and the redshifts we measured are
consistent (Δz<0.005) with the published values for all six
sources (see Section 3.1),
2 = redshift reported in Paper I (Cheung, 2007, Cat. J/AJ/133/2097) and
the spectrum is now presented,
3 = new FIRST X-shaped radio source candidate not presented in Paper I and
described in Appendix B: FIRST J1018+2914 (4C+29.38, B2 1015+29)
identified with SDSS J101827.09+291420.3,
4 = tentative redshift due to relatively low S/N(∼5) of the spectrum,
5 = new redshift superseding previous estimate for two objects (see
Section 3.2).
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Seq Catalog number in Paper I (<[C2007] NNN> or
<[C2007] XNN> in Simbad) (G1)
5- 14 A10 --- [C2007] JHHMM+DDMM (J2000) name
16- 19 F4.1 mag mag [13.2/21] Observed optical magnitude (1)
20 A1 --- n_mag [a-g] Magnitude band (2)
22- 27 F6.4 --- z [0.037/0.65] Redshift (3)
29- 32 F4.2 --- Kcor [0.04/1.34] K-corrections (4)
34- 37 F4.2 --- Av [0.03/2.6] Extinction corrections adopting
R- and V-band values based on
Schlegel+ 1998ApJ...500..525S 1998ApJ...500..525S maps
39- 43 F5.2 [W/Hz] [L1.4GHz] [24.4/27.3] Logarithm of the total source
radio luminosity at 1.4GHz (5)
45- 49 F5.1 mag RMAG [-25/-21.6] Absolute R-band magnitude (6)
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Note (1): The observed optical magnitudes are predominantly SDSS r-band values
unless otherwise indicated with a flag (See n_mag column).
Note (2): Flags for less accurate (by as much as ∼0.5-1mag) known X-shaped
radio objects as follows:
a = Cousins R-band magnitude (Wold et al., 2007A&A...470..531W 2007A&A...470..531W)
b = Cousins R-band magnitude (Govoni et al., 2000A&AS..143..369G 2000A&AS..143..369G)
c = Cousins R-band magnitude (USNO-B1 catalog, Cat. I/284,
Monet et al., 2003)
d = V-band magnitude (de Vaucouleurs et al., 1991RC3v9.C......0D 1991RC3v9.C......0D)
e = V-band magnitude (Smith & Heckman, 1989ApJS...69..365S 1989ApJS...69..365S)
f = V-band magnitude (Spinrad et al., 1985, Cat. J/PASP/97/932)
g = R-band value from the USNO-B1 catalog (for candidate sources)
Note (3): Redshifts are gathered from Paper I (Tables 1 and 2 therein;
Cheung, 2007, Cat. J/AJ/133/2097) and Table 1 of this paper and are
listed here for convenience.
Note (4): K-corrections adopted based on R-band values from Fukugita et
al., 1995PASP..107..945F 1995PASP..107..945F as tabulated in Urry et al.,
2000ApJ...532..816U 2000ApJ...532..816U. In the few cases where V-band measurements were
used (all z<0.2), the additional uncertainty due to utilizing the
K-correction at R-band is negligible in comparison to the uncertainty
in the published magnitudes.
Note (5): The radio fluxes used were tabulated in Paper I (Tables 1 and 2
therein; Cheung, 2007, Cat. J/AJ/133/2097).
Note (6): Absolute R-band magnitude with K- and extinction corrections
applied. Transformations assumed colors of r-R=0.25 and V-R=0.61,
appropriate for giant ellipticals (Fukugita et al.,
1995PASP..107..945F 1995PASP..107..945F).
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Global Notes:
Note (G1): Catalog number based on entry order in Table 1 (prepended
with X) and Table 2 of Paper I (Cheung, 2007, Cat. J/AJ/133/2097,
<[C2007] NNN> in Simbad) containing the lists of the known (XNN) and
candidate (NN) X-shaped radio sources, respectively.
Acknowledgements:
Cheung, Chi C (Teddy) [chi.c.cheung2.civ at us.navy.mil]
History:
From electronic version of the journal
* 17-Jan-2010: Insert into VizieR
* 25-Sep-2024: spectra added -- sent by the author
References:
Cheung C.C. Paper I. 2007AJ....133.2097C 2007AJ....133.2097C Cat. J/AJ/133/2097
(End) Emmanuelle Perret [CDS] 02-Nov-2009