Optical and Radio Properties of Extragalactic Sources Observed by the FIRST Survey and the Sloan Digital Sky Survey

By Željko Ivezic´, Kristen Menou, G. Knapp, M. Strauss, Robert Lupton, D. V. vanden Berk, Gordon Richards, Christy A. Tremonti, M. Weinstein, S. Anderson and 30 more. 2002

424 citations recorded by the source corpus.

We discuss the optical and radio properties of ∼30,000 FIRST (radio, 20 cm, sensitive to 1 mJy) sources positionally associated within 1.″5 with a Sloan Digital Sky Survey (SDSS) (optical, sensitive to r* ∼ 22.2) source in 1230 deg2 of sky. The matched sample represents ∼30% of the 108,000 FIRST sources and 0.1% of the 2.5 × 107 SDSS sources in the studied region. SDSS spectra are available for 4300 galaxies and 1154 quasars from the matched sample and for a control sample of 140,000 galaxies and 20,000 quasars in 1030 deg2 of sky. Here we analyze only core sources, which dominate the sample; the fraction of SDSS-FIRST sources with complex radio morphology is determined to be less than 10%. This large and unbiased catalog of optical identifications provides much firmer statistical footing for existing results and allows several new findings. The majority (83%) of the FIRST sources identified with an SDSS source brighter than r* = 21 are optically resolved; the fraction of resolved objects among the matched sources is a function of the radio flux, increasing from ∼50% at the bright end to ∼90% at the FIRST faint limit. Nearly all optically unresolved radio sources have nonstellar colors indicative of quasars. We estimate an upper limit of ∼5% for the fraction of quasars with broadband optical colors indistinguishable from those of stars. The distribution of quasars in the radio flux–optical flux plane suggests the existence of the "quasar radio dichotomy"; 8% ± 1% of all quasars with i* < 18.5 are radio-loud, and this fraction seems independent of redshift and optical luminosity. The radio-loud quasars have a redder median color by 0.08 ± 0.02 mag, and show a 3 times larger fraction of objects with extremely red colors. FIRST galaxies represent 5% of all SDSS galaxies with r* < 17.5, and 1% for r* < 20, and are dominated by red (u*-r* > 2.22) galaxies, especially those with r* > 17.5. Magnitude- and redshift-limited samples show that radio galaxies have a different optical luminosity distribution than nonradio galaxies selected by the same criteria; when galaxies are further separated by their colors, this result remains valid for both blue and red galaxies. For a given optical luminosity and redshift, the observed optical colors of radio galaxies are indistinguishable from those of all SDSS galaxies selected by identical criteria. The distributions of radio-to-optical flux ratio are similar for blue and red galaxies in redshift-limited samples; this similarity implies that the difference in their luminosity functions and resulting selection effects are the dominant cause for the preponderance of red radio galaxies in flux-limited samples. The fraction of radio galaxies whose emission-line ratios indicate an AGN (30%), rather than starburst, origin is 6 times larger than the corresponding fraction for all SDSS galaxies (r* < 17.5). We confirm that the AGN-to-starburst galaxy number ratio increases with radio flux and find that radio emission from AGNs is more concentrated than radio emission from starburst galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/9ca9978732aab959f35e75982fb9c7375ea99259

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

A UNIFIED CATALOG OF RADIO OBJECTS DETECTED BY NVSS, FIRST, WENSS, GB6, AND SDSS (2008, methodology): “(8) This spectral index relates the 92 cm flux to the SDSS i band flux6, and can be converted to the often used radio loudness measure, Ri = 0.4(i − tFIRST) (e.g. Ivezić et al. 2002) via α92i = 0.11α 92 20 − 0.16 Ri.”
Star Formation Rate Indicators in the Sloan Digital Sky Survey (2003, background): “This point is relevant since LRGs were noted by Ivezić et al. (2002) to have a relatively high fraction of radio counterparts.”
THE LAST OF FIRST: THE FINAL CATALOG AND SOURCE IDENTIFICATIONS (2015, background): “Ivezić et al. (2002) reported that roughly 30% of the initial batch of 105 FIRST sources had optical counterparts in SDSS, the large majority of which (83”
The quest for dual and binary supermassive black holes: A multi-messenger view (2019, background): “However, a severe limitation of its applicability is that only a minority of AGN, less than 10 per cent of the population, are strong (i.e. at least mJy-level) radio emitters (e.g. Ivezić et al., 2002).”
X-Ray Emission from Radio-Quiet Quasars in the Sloan Digital Sky Survey Early Data Release: The αox Dependence upon Ultraviolet Luminosity (2002, methodology): “We have focused on the RQQs, since they make up the bulk of the quasar population ( 85%–90%; e.g., Stern et al. 2000; Ivezić et al. 2002) and are not strongly affected by jet emission or boosting effects.”
EFFICIENT PHOTOMETRIC SELECTION OF QUASARS FROM THE SLOAN DIGITAL SKY SURVEY. II. ∼1, 000, 000 QUASARS FROM DATA RELEASE 6 (2004, background): “The apparent low fraction of radio-detected sources should not be taken as an indication that the fraction of quasars that are radio loud is lower than the nominal 8%–10% (e.g., Ivezić et al. 2002).”
UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C iv EMISSION (2010, background): “Radio selection, while contributing less than 1% to the colorselected sample (Ivezić et al. 2002), is important for our consideration of the differences between RL and radio-quiet (RQ) quasars.”
MODELING THE TIME VARIABILITY OF SDSS STRIPE 82 QUASARS AS A DAMPED RANDOM WALK (2010, methodology): “%) is considerably lower than that in the Northern galactic cap footprint of the SDSS for the magnitude range 19 < i < 20 (White et al. 1997; Ivezić et al. 2002).”
Accretion states and radio loudness in active galactic nuclei: analogies with X-ray binaries (2006, methodology): “…the expressions for our Kcorrection terms from Section 2.2.1, R is related to fluxes from the catalogues by the expression log R = 0.4(B − t) (5) (Ivezić et al. 2002), where t is the K-corrected 1.4-GHz radio AB magnitude given by t = −2.5[log (f FIRST/3631 Jy) + 0.5 log (1 + z)] and B is the…”
Supermassive black holes in elliptical galaxies: switching from very bright to very dim (2005, background): “To provide further support to Fig.1, we note that ∼90% of QSOs do not show strong radio emission (e.g. Ivezić et al. 2002), indicating that powerful outflows are not a necessary property of rapidly accreting SMBHs.”
Quasars: the characteristic spectrum and the induced radiative heating (2003, background): “…of radio-quiet and radioloud quasars are quite similar up to ∼ 100 eV (Elvis et al. 1994), with ≈ 90% of all quasars being radio quiet and this fraction being seemingly independent of redshift and bolometric luminosity (Stern et al. 2000; Ivezić et al. 2002; see however Cirasuolo et al. 2003).”
A sample of radio-loud active galactic nuclei in the Sloan Digital Sky Survey (2005, methodology): “Ivezić et al. (2002) cross-correlated the FIRST survey with the SDSS imaging sample.”
The Sloan Digital Sky Survey Quasar Survey: Quasar Luminosity Function from Data Release 3 (2006, background): “Radio selection, while adding less than 1% to the color-selected sample (as most radio-selected quasars are also color selected; Ivezić et al. 2002), helps to improve our selection completeness at these redshifts.”
Active galactic nuclei: what’s in a name? (2017, background): “…in the logarithm of the ratio of flux density or luminosity in the radio band and that within a wavelength range Δλ, which can either be in the optical (e.g. B-band; Kellermann et al. 1989; r-, i-, or z-band; Ivezić et al. 2002) or IR (e.g. 24 µm; Padovani et al. 2011; Bonzini et al. 2013).”
Quasar feedback and the origin of radio emission in radio-quiet quasars (2014, background): “…function of active nuclei remains a topic of much debate, including whether there is a very broad distribution of intrinsic luminosities or whether there is a true dichotomy in this property (Kellermann et al. 1989; Xu et al. 1999; Ivezić et al. 2002; Jiang et al. 2007; Condon et al. 2013).”
Candidate Type II Quasars from the Sloan Digital Sky Survey. I. Selection and Optical Properties of a Sample at 0.3 < Z < 0.83 (2003, methodology): “The column titled ‘‘ FIRST ’’ gives the integrated flux density in mJy at 20 cm (Ivezić et al. 2002) from the FIRST survey for objects with FIRST matches within 300.”
The host galaxies of active galactic nuclei (2003, neutral): “Further clues to the connection between type 2 AGN, QSOs, ULIRGs and radio galaxies will come from direct cross-correlation of our sample with infrared and radio surveys such as IRAS and FIRST (e.g. Ivezić et al. 2002).”
The Radio-Loud Fraction of Quasars is a Strong Function of Redshift and Optical Luminosity (2006, methodology): “This result is in quantitative agreement with the marginal RLF derived by Ivezić et al. (2002).”