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
ADC_Keywords: Galaxies, radio ; Redshifts ; Spectroscopy 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. A summary of the observations is presented in Table1. File Summary:
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
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 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 "YYYY/MM/DD" ObsDate Observation date 37- 40 I4 s Exp Total exposure time 42- 46 F5.3 --- z Measured redshift 48- 50 A3 --- n_z Absorption (abs) or emission (em) feature 52 A1 --- f_z Note on redshift (3)
Note (2): Telescopes as follows: HET = Hobby-Eberly Telescope; HJST = Harlan J. Smith Telescope; MMT = Multi-Mirror Telescope. 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).
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 XNN in Simbad) (G1) 5- 14 A10 --- [C2007] JHHMM+DDMM (J2000) name 16- 19 F4.1 mag mag Observed optical magnitude (1) 20 A1 --- n_mag [a-g] Magnitude band (2) 22- 27 F6.4 --- z Redshift (3) 29- 32 F4.2 --- Kcor K-corrections (4) 34- 37 F4.2 --- Av Extinction corrections adopting R- and V-band values based on Schlegel et al. (1998ApJ...500..525S) maps 39- 43 F5.2 [W/Hz] [L1.4GHz] Logarithm of the total source radio luminosity at 1.4GHz. (5) 45- 49 F5.1 mag RMAG Absolute R-band magnitude (6)
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) b = Cousins R-band magnitude (Govoni et al., 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) e = V-band magnitude (Smith & Heckman, 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 as tabulated in Urry et al., 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).
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.
History: From electronic version of the journal References: Cheung C.C. Paper I. 2007AJ....133.2097C; Cat. J/AJ/133/2097
(End) Emmanuelle Perret [CDS] 02-Nov-2009
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