The ultraluminous and hyperluminous infrared galaxies in the Sloan Digital Sky Survey, 2dF Galaxy Redshift Survey and 6dF Galaxy Survey

Abstract

We present a result of cross‐correlating the Infrared Astronomical Satellite Faint Source Catalogue with the spectroscopic catalogues of galaxies in the Fourth Data Release of the Sloan Digital Sky Survey, the Final Data Release of the 2dF Galaxy Redshift Survey (2dFGRS) and the Second Data Release of the 6dF Galaxy Survey. We have identified 324 ultraluminous infrared galaxies (ULIRGs) including 190 newly discovered ULIRGs, and two hyperluminous infrared galaxies. Adding these new ULIRGs, we increase the number of known ULIRGs by about 30 per cent. The reliability of the cross‐correlation is estimated using the likelihood ratio method. The incompleteness of our sample introduced by the identification procedure in this study is estimated to be about 5 per cent. Our sample covers the redshift range of z= 0.037–0.517 with a median redshift of , which is larger than that of the sample of previously known ULIRGs.

The candidate Seyfert 1-like objects found from ULIRGs in the Sloan Digital Sky Survey, 2dF Galaxy Redshift Survey and 6dF Galaxy Survey

“…Therefore we used the IRAS positional error ellipse to restrict the cross-identifications because the IRAS error ellipse has a 95% confidence level (IRAS Explanatory Supplement 1988, hereafter IRAS ES). Hwang et al (2007) also gave SDSS identifications for some sources in their Table 1, but over half of their sources have no SDSS counterparts. SDSS identifications and positions for some sources can be found in their Table 1.…”

“…In Hwang et al (2007 gave the largest sample so far of ULIRGs, containing 324 sources, in the SDSS-2dF-6dF Survey. In this sample 190 ULIRGs are newly discovered.…”

“…The best known samples of IRAS luminous and ultraluminous galaxies are the Bright Galaxy Sample (Soifer et al 1987), recently significantly updated into the Revised Bright Galaxy Sample (Sanders et al 2003), the IRAS 2 Jy sample (Strauss et al 1990), the IRAS 1 Jy sample (Kim et al 1998a), the FIRST/IRAS sample (Stanford et al 2000) and the sample of the Sloan Digital Sky Survey, 2dF Galaxy Redshift Survey and 6dF Galaxy Survey (Hwang et al 2007, hereafter the SDSS-2dF-6dF sample). Of these the IRAS 1 Jy sample and the SDSS-2dF-6dF sample are special surveys for pure ULIRGs.…”

“…First of all, crossidentifications are made between the sample from the SDSS2dF-6dF Survey and the 2MASS Point Source Catalog (hereafter 2MASS PSC). Hwang et al (2007) gave all source positions from the IRAS Faint Source Catalog (hereafter IRAS FSC) where the positional accuracy is typically 10 -30 , while in the 2MASS PSC the positional accuracy is typically less than 2 arc-second, which is much smaller than the positional accuracy of IRAS. Therefore we used the IRAS positional error ellipse to restrict the cross-identifications because the IRAS error ellipse has a 95% confidence level (IRAS Explanatory Supplement 1988, hereafter IRAS ES).…”

“…All identified 2MASS associations of the sample from SDSS-2dF-6dF Survey are listed in Table 1. The items in the columns of Table 1 are listed as follows: (1) IRAS FSC name; (2) redshift from Hwang et al (2007); (3) and (4) the R.A. and Dec. in 2MASS PSC at the epoch of 2000 respectively; (5)-(7) the JHK magnitudes and their uncertainties in the bracket from 2MASS PSC respectively; (8)-(11) the IRAS flux densities (in Jy) and their uncertainties in the bracket from IRAS FSC at 12, 25, 60 and 100 μm respectively; (12) the flux quality in IRAS observations (note that "1" indicates the upper-limited value and will not be used in following discussions); (13) the spectral type given by Kim et al (1998b) and Veilleux et al (1999a) for the IRAS 1 Jy sample in the working sample. It should be noted that if there is a blank in the JHK magnitude uncertainty, it means the upper-limited observation from 2MASS PSC.…”