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FIRST Radio Sources (first + radio_source)
Selected AbstractsThe redshift distribution of FIRST radio sources at 1 mJyMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2000M. Magliocchetti We present spectra for a sample of radio sources from the FIRST survey, and use them to define the form of the redshift distribution of radio sources at mJy levels. We targeted 365 sources and obtained 46 redshifts (13 per cent of the sample). We find that our sample is complete in redshift measurement to R,18.6, corresponding to z,0.2. Galaxies were assigned spectral types based on emission-line strengths. Early-type galaxies represent the largest subset (45 per cent) of the sample and have redshifts 0.15,z,0.5; late-type galaxies make up 15 per cent of the sample and have redshifts 0.05,z,0.2; starbursting galaxies are a small fraction (,6 per cent), and are very nearby (z,0.05). Some 9 per cent of the population have Seyfert 1/quasar-type spectra, all at z,0.8, and 4 per cent are Seyfert 2 type galaxies at intermediate redshifts (z,0.2). Using our measurements and data from the Phoenix survey (Hopkins et al.), we obtain an estimate for N(z) at S1.4 GHz,1 mJy and compare this with model predictions. At variance with previous conclusions, we find that the population of starbursting objects makes up ,5 per cent of the radio population at S,1 mJy. [source] The K - z diagram of FIRST radio sources identified in the Boötes and Cetus fieldsASTRONOMISCHE NACHRICHTEN, Issue 8 2009K. El Bouchefry Abstract This paper presents the Hubble diagram (K - z relation) for FIRST (Faint Images of the Radio Sky at 20 cm) radio sources identified in the Boötes and Cetus fields. The correlation between the K magnitude of the FIRST-NDWFS sample and the photometric redshifts found to be linear. The dispersion about the best fit line is given by 1.53 for the whole sample and 0.75 at z > 1. The paper also presents a composite K - z diagram of FIRST radio sources and low-frequency selected radio samples with progressively fainter flux-density limits (3CRR, 6C, 7CRS and the EIS-NVSS sample). The majority of FIRST radio sources lie fainter than the no evolution curve (3 L* galaxies) probably highlighting the fact that the galaxy luminosity is correlated with the radio power (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The FIRST radio survey: Panchromatic properties of FIRST radio sources identified in the Boötes and Cetus fieldsASTRONOMISCHE NACHRICHTEN, Issue 1 2009K. El Bouchefry Abstract In this paper the availability of multi-wavelength optical/infrared information of FIRST (Faint Images of the Radio Sky at 20 cm) radio sources counterparts over ,9.2 deg2 in the Boötes field and ,2.4 deg2 in the Cetus field is exploited to infer the physical properties of the faint radio population. The radio sources optically identified have been divided into resolved galaxies and stellar-like objects finding that the faint radio population is mainly composed of early-type galaxies with very red colour (Bw , R , 4.6). A total number of 57 counterparts of FIRST radio sources have extremely red colour (R , K , 5). Photometric redshift from Hyperz implies that the Extremely Red Objects (EROs) counterparts to FIRST radio sources are mostly located in the range z = 0.7,2, with the bulk of the population at z , 1. Taking advantage of the near infrared imaging with FLAMEX (FLAMINGOS Extragalactic Infrared Survey), the EROs counterparts to FIRST radio sources are separated into passively-evolving and dusty star-forming galaxies using their RJK colours; the relatively blue J , K of these galaxies suggest that most are old elliptical galaxies (18/25) rather than dusty starburst galaxies (7/25). A total of 15 Distant Red Galaxy (DRGs) have been identified as counterparts to FIRST radio sources in the Cetus field and 3 DRGs in the Boötes field with J , K > 2.3 (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Identifications of FIRST radio sources in the NOAO Deep Wide-Field SurveyASTRONOMISCHE NACHRICHTEN, Issue 6 2007K. El Bouchefry Abstract In this paper we present the results of an optical and near infrared identification of 514 radio sources from the FIRST survey (Faint Images of the Radio Sky Survey at Twenty centimetres) with a flux-density limit of 1 mJy in the NOAO Deep Wide-Field Survey (NDWFS) Boötes field. Using optical (Bw, R, I) and K band data with approximate limits of Bw , 25.5 mag, R , 25.8 mag, I , 25.5 mag and K , 19.4 mag, optical counterparts have been identified for 378 of 514 FIRST radio sources. This corresponds to an identification rate of 34% in four bands (BwRIK), 60% in optical bands (BwRI) and 74% in the I band. Photometric redshifts for these sources have been computed using the hyperz code. The inclusion of quasar template spectra in hyperz is investigated. We note that the photometric data are, in many cases, best matched to templates with very short star-formation timescales and the inferred ages of identified galaxies depend strongly on the assumptions about the star-formation timescale. The redshifts obtained are fairly consistent with those expected from the K - z relation for brighter radio sources but there is more scatter in the K - z diagram at z < 1. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||