Incidence of Mg ii absorbers towards blazars and the GRB/QSO puzzle

Bergeron, J.; Boissé, Patrick; Ménard, Brice

doi:10.1051/0004-6361/201015265

Cited by 25 publications

(36 citation statements)

References 72 publications

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“…Mg ii emission line (Bergeron et al 2011) and is consistent with the photometric redshift of this source (Rau et al 2012, z = 1.47 +0.11 −0.12 ). If the source classification as a BL Lac is correct, PKS 0332−403 would be one of only two BL Lac objects with z > 1.3 in the Fermi 2FGL sample (Rau et al 2012).…”

Section: Individual Sourcessupporting

confidence: 86%

Radio and gamma-ray properties of extragalactic jets from the TANAMI sample

Böck

Kadler

Müller

et al. 2016

A&A

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The TANAMI program has been observing parsec-scale radio jets of southern (declination south of −30 • ) γ-ray bright AGN, simultaneously with Fermi/LAT monitoring of their γ-ray emission, via high-resolution radio imaging with Very Long Baseline Interferometry techniques. We present the radio and γ-ray properties of the TANAMI sources based on one year of contemporaneous TANAMI and Fermi/LAT data. A large fraction (72%) of the TANAMI sample can be associated with bright γ-ray sources for this time range. Association rates differ for different optical classes with all BL Lacs, 76% of quasars, and just 17% of galaxies detected by the LAT. Upper limits were established on the γ-ray flux from TANAMI sources not detected by LAT. This analysis led to the identification of three new Fermi sources whose detection was later confirmed. The γ-ray and radio luminosities are related by L γ ∝ L 0.89 ± 0.04 r . The brightness temperatures of the radio cores increase with the average γ-ray luminosity and the presence of brightness temperatures above the inverse Compton limit implies strong Doppler boosting in those sources. The undetected sources have lower γ/radio luminosity ratios and lower contemporaneous brightness temperatures. Unless the Fermi/LAT-undetected blazars are much γ-ray-fainter than the Fermi/LAT-detected sources, their γ-ray luminosity should not be significantly lower than the upper limits calculated here.

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Section: Individual Sourcessupporting

confidence: 86%

Radio and gamma-ray properties of extragalactic jets from the TANAMI sample

Böck

Kadler

Müller

et al. 2016

A&A

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“…Stocke & Rector (1997) find five strong Mg ii absorbers in the spectra of ten BL Lac objects -this is larger by a factor of 4-5 than the number of strong absorbers expected based upon quasar sight-lines. Bergeron et al (2011) investigate strong intervening Mg ii absorption for blazars in general (of which BL Lac objects are a subtype) -they find a factor 2.2 +0.8 −0.6 higher incidence of strong absorbers in blazar spectra compared to quasars. They argue that dust obscuration affects the quasar sample and not the blazar sample, as blazars are usually identified in bands that are not sensitive to dust obscuration.…”

Section: Implications Of Dust Extinctionmentioning

confidence: 99%

Constraints on the relative sizes of intervening Mg II-absorbing clouds and quasar emitting regions

Lawther¹,

Paarup²,

Schmidt³

et al. 2012

A&A

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Context.A significantly higher incidence of strong (rest equivalent width W r > 1 Å) intervening Mg ii absorption is observed along gamma-ray burst (GRB) sight-lines relative to those of quasar sight-lines. A geometrical explanation for this discrepancy has been suggested: the ratio of the beam size of the source to the characteristic size of an Mg ii absorption system can influence the observed Mg ii equivalent width, if these two sizes are comparable. Aims. We investigate whether the differing beam sizes of the continuum source and broad-line region of Sloan Digital Sky Survey (SDSS) quasars produce a discrepancy between the incidence of strong Mg ii absorbers illuminated by the quasar continuum region and those of absorbers illuminated by both continuum and broad-line region light. Methods. We performed a semi-automated search for strong Mg ii absorbers in the SDSS Data Release 7 quasar sample. The resulting strong Mg ii absorber catalog is available at the CDS. We measured the sight-line number density of strong Mg ii absorbers superimposed on and off the quasar C iv λ 1550 and C iii] λ 1909 emission lines. Results. We see no difference in the sight-line number density of strong Mg ii absorbers superimposed on quasar broad emission lines compared to those superimposed on continuum-dominated spectral regions. This suggests that the Mg ii absorbing clouds typically observed as intervening absorbers in quasar spectra are larger than the beam sizes of both the continuum-emitting regions and broad line-emitting regions in the centers of quasars, corresponding to a lower limit of the order of 10 17 cm for the characteristic size of an Mg ii absorbing cloud.

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“…We only report a tentative detection of the MgII doublet at the redshift z = 1.215, consistent with that by . In addition, we detect the intervening absorber seen by Bergeron, Boissé, & Ménard (2011) Table 2). Line rest-frame EW (Å) rest-frame EW (Å) rest-frame EW (Å) rest-frame EW (Å) rest-frame EW (Å)…”

Section: Bzbj2031+1219 (Pks 2029+121)mentioning

confidence: 74%

Are many radio-selected BL Lacs radio quasars in disguise?

D’Elia¹,

Padovani²,

Giommi³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We show that a blazar classification in BL Lacs and Flat Spectrum Radio Quasars may not be adequate when it relies solely on the equivalent widths (EWs) of optical lines. In fact, depending on redshift, some strong emission lines can fall in the infrared window and be missed. We selected a sample of BL Lacs with firm redshift identification and good visibility from Paranal. We targeted with the X-shooter spectrograph the five BL Lacs with z > 0.7, i.e., those for which the Hα line, one of the strongest among blazars, falls outside the optical window and determined the EW of emission lines in both the infrared and optical bands. Two out of five sources show an observed Hα EW > 5Å (one has rest frame EW > 5Å) and could be classified as FSRQs by one of the classification schemes used in the literature. A third object is border-line with an observed EW of 4.4 ± 0.5Å. In all these cases Hα is the strongest emission line detected. The Hα line of the other two blazars is not detected, but in one case it falls in a region strongly contaminated by sky lines and in the other one the spectrum is featureless. We conclude that a blazar classification based on EW width only can be inaccurate and may lead to an erroneous determination of blazar evolution. This effect is more severe for the BL Lac class, since FSRQs can be misclassified as BL Lacs especially at high redshifts (z > 0.7), where the latter are extremely rare.

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Incidence of Mg ii absorbers towards blazars and the GRB/QSO puzzle

Cited by 25 publications

References 72 publications

Radio and gamma-ray properties of extragalactic jets from the TANAMI sample

Radio and gamma-ray properties of extragalactic jets from the TANAMI sample

Constraints on the relative sizes of intervening Mg II-absorbing clouds and quasar emitting regions

Are many radio-selected BL Lacs radio quasars in disguise?

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