The Deep X-Ray Radio Blazar Survey (DXRBS) -- II. New identifications

Landt, Hermine; Padovani, P.; Perlman, Eric S.; Giommi, P.; Bignall, H. E.; Tzioumis, A. K.

doi:10.1046/j.1365-8711.2001.04269.x

Cited by 95 publications

(123 citation statements)

References 42 publications

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“…The measurements of both flux density and size of the core at mas scale, together with the available red shift (Perlman et al 1998;Landt et al 2001) allowed us to calculate lower limits of the brightness temperature T b . T b ranges between 10 7 K and 10 12 K. The mean value is 6 ± 16 × 10 10 K and the median T b = 0.9 +0.1 −0.6 × 10 10 K. There are 19 sources that are unresolved when deconvolved by the beam.…”

Section: Brightness Temperaturementioning

confidence: 99%

“…For the 87 DXRBS objects observed in the northern sky, we improved their positional accuracy by deriving the positions from the FIRST (Becker et al 1994) and from the NVSS (Condon et al 1998; see Mantovani et al 2011). For 91 DXRBS objects in the southern sky with declination <−10 deg, the NVSS or ATCA positions are taken from Landt et al (2001) and Perlman et al (1998). Nine of the sources observed with the EVN show a good positional overlapping, which holds for an association between these radio sources and γ objects.…”

Section: Association To a γ-Ray Objectmentioning

confidence: 99%

“…J0204.8+1514 was included in the MOJAVE programme selected because it was classified flat spectrum source, which does not seem to be Notes. Column 1: source name; 2: source class; 3−5: major axis, minor axis in arcseconds and position angle of the major axis in degrees; 6: source angular size extracted from FIRST (F) or NVSS (N) catalogues; 7: linear size computed using H 0 = 100 km s −1 Mpc −1 , q 0 = 1) 8: EVN structure; 9: ROSAT X-ray flux (Perlman et al 1998;Landt et al 2001); 10: X-ray luminosity computed using www.astro.soton.ac.uk/~td/ flux_convert.html with cosmological parameters H 0 = 70 km s −1 Mpc −1 , Ω m = 0.27, Ω vac = 0.73 11: nH column density (computed for cone radius of 0.5 deg from input position using heasarc.gsfc.nasa.gov/cgi-bin/Tools/; numbers are (LAB Average + DL Average nH) / 2); 12−13: polarisation percentage at 8.35 GHz and 10.45 GHz (Mantovani et al 2011). The median value of m for CSS at 8.35 GHz is <1% (Mantovani et al 2009); 14: rotation measure (Mantovani et al 2009).…”

Section: Association To a γ-Ray Objectmentioning

confidence: 99%

“…Keeping that in mind, we updated the Pushkarev et al (2010) plot by adding data pairs that have the radio flux density taken from our EVN measurements and the ATCA measurements made by Perlman et al (1998) and Landt et al (2001) and the integrated γ-ray photon flux of the associated Fermi objects, evaluated from the fit of the full band (100 MeV−100 GeV), taken from the 2FGL catalogue (Nolan et al 2012). The updated plot is shown in Fig.…”

Section: Comparison Between High-and Low-power Samples Of Blazarsmentioning

confidence: 99%

“…This is quite unexpected since BL Lacs show flat spectral index in the radio band. It is worth mentioning that the optical classification of these three objects as BL Lacs is questionable (see Perlman et al 1998;Landt et al 2001) …”

Section: Steep-spectrum and Gigahz-peaked Sourcesmentioning

confidence: 99%

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A sample of weak blazars at milli-arcsecond resolution

Mantovani

Bondì

Mack

et al. 2015

A&A

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Aims. We started a follow-up investigation of the "Deep X-ray Radio Blazar Survey" objects with declination >−10 deg to better understand the blazar phenomenon. We undertook a survey with the European Very Long Baseline Interferometry Network at 5 GHz to make the first images of a complete sample of weak blazars, aiming at a follow-up comparison between high-and low-power samples of blazars. Methods. We observed 87 sources with the EVN at 5 GHz during the period October 2009 to May 2013. The observations were correlated at the Max-Planck-Institut für Radioastronomie and at the Joint Institute for VLBI in Europe. The correlator output was analysed using both the AIPS and DIFMAP software packages. Results. All of the sources observed were detected. Point-like sources are found in 39 cases on a milli-arcsecond scale, and 48 show core-jet structure. The total flux density distribution at 5 GHz has a median value S = 44 +23 −10 mJy. A total flux density ≤150 mJy is observed in 68 out of 87 sources. Their brightness temperature T b ranges between 10 7 K and 10 12 K. According to the spectral indices previously obtained with multi-frequency observations, 58 sources show a flat spectral index, and 29 sources show a steep spectrum or a spectrum peaking at a frequency around 1−2 GHz. Adding to the DXRBS objects we observed those already observed with ATCA in the Southern sky, we found that 14 blazars and a Steep Spectrum Radio Quasars, are associated to γ-ray emitters. Conclusions. We found that 56 sources can be considered blazars. We also detected 2 flat spectrum narrow line radio galaxies. About 50% of the blazars associated to a γ-ray object are BL Lacs, confirming that they are more likely detected among blazars γ-emitters. We confirm the correlation found between the source core flux density and the γ-ray photon fluxes down to fainter flux densities. We also found that weak blazars are also weaker γ-ray emitters compared to bright blazars. Twenty-two sources are SSRQs or Compact Steep-spectrum Sources, and 7 are GigaHz Peaked Sources. The available X-ray ROSAT observations allow us to suggest that CSS and GPS quasars are not obscured by large column of cold gas surrounding the nuclei. We did not find any significant difference in X-ray luminosity between CSS and GPS quasars.

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Section: Brightness Temperaturementioning

confidence: 99%

Section: Association To a γ-Ray Objectmentioning

confidence: 99%

Section: Association To a γ-Ray Objectmentioning

confidence: 99%

Section: Comparison Between High-and Low-power Samples Of Blazarsmentioning

confidence: 99%

Section: Steep-spectrum and Gigahz-peaked Sourcesmentioning

confidence: 99%

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A sample of weak blazars at milli-arcsecond resolution

Mantovani

Bondì

Mack

et al. 2015

A&A

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The Observational Properties of Blazars; Selection, Relationships and Unification

Browne

2004

The Role of VLBI in Astrophysics, Astrometry and Geodesy

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Mining the Blazar Sky

Padovani

Giommi

Eso Astrophysics Symposia

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We present the results of our methods to "mine" the blazar sky, i.e., select blazar candidates with very high efficiency. These are based on the cross-correlation between public radio and X-ray catalogs and have resulted in two surveys, the Deep X-ray Radio Blazar Survey (DXRBS) and the "Sedentary" BL Lac survey. We show that data mining is vital to select sizeable, deep samples of these rare active galactic nuclei and we touch upon the identification problems which deeper surveys will face.Comment: 7 pages, 2 figures. To appear in the proceedings of the Workshop "Mining the Sky", Munich, August 2000, ESO Astrophysics Symposia, in press. Postscript file also available at http://www.stsci.edu/~padovani/survey.htm

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The Deep X-Ray Radio Blazar Survey (DXRBS) -- II. New identifications

Cited by 95 publications

References 42 publications

A sample of weak blazars at milli-arcsecond resolution

A sample of weak blazars at milli-arcsecond resolution

The Observational Properties of Blazars; Selection, Relationships and Unification

Mining the Blazar Sky

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