SPECTROSCOPY OF THE LARGEST EVER γ-RAY-SELECTED BL LAC SAMPLE

By M. Shaw, R. Romani, G. Cotter, S. E. Healey, P. Michelson, A. Readhead, J. Richards, W. Max-Moerbeck, O. King, W. Potter. 2013

166 citations recorded by the source corpus.

We report on spectroscopic observations covering most of the 475 BL Lacs in the second Fermi Large Area Telescope (LAT) catalog of active galactic nuclei (AGNs). Including archival measurements (correcting several erroneous literature values) we now have spectroscopic redshifts for 44% of the BL Lacs. We establish firm lower redshift limits via intervening absorption systems and statistical lower limits via searches for host galaxies for an additional 51% of the sample leaving only 5% of the BL Lacs unconstrained. The new redshifts raise the median spectroscopic from 0.23 to 0.33 and include redshifts as large as z = 2.471. Spectroscopic redshift minima from intervening absorbers have , showing a substantial fraction at large z and arguing against strong negative evolution. We find that detected BL Lac hosts are bright ellipticals with black hole masses M• ∼ 108.5 − 109, substantially larger than the mean of optical AGNs and LAT Flat Spectrum Radio Quasar samples. A slow increase in M• with z may be due to selection bias. We find that the power-law dominance of the optical spectrum extends to extreme values, but this does not strongly correlate with the γ-ray properties, suggesting that strong beaming is the primary cause of the range in continuum dominance.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/791931a7dd3bba373cfabea4092abb1b03f12d94

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In Astronomy and Astrophysics

1. A. Strong
2. E. Orlando
3. Anna Franckowiak
4. M. Lister
5. Y. Kovalev
6. T. Savolainen
7. A. Pushkarev
8. Y. Inoue

In Nuclear and High Energy Physics

1. A. Strong
2. E. Orlando
3. Anna Franckowiak
4. M. Lister
5. Y. Kovalev
6. Y. Inoue
7. T. Savolainen
8. A. Pushkarev

Citations in the corpus

• THE ORIGIN OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND AND IMPLICATIONS FOR DARK MATTER ANNIHILATION (2015, methodology): “Taking advantage of recent follow up observations (e.g., Shaw et al. 2013; Ajello et al. 2014), we derive new models for the luminosity and redshift evolution of the whole blazar class and of its SED.”
• THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2015, methodology): “The redshift quoted in 2LAC was 0.35, but a recent measurement by Shaw et al. (2013) gives z = 1.596, identifying a significant broad emission feature with C IV, consistent with a weak bump in the far blue at Lyα.”
• 2FHL: THE SECOND CATALOG OF HARD FERMI-LAT SOURCES (2015, background): “Spectroscopic redshift measurements exists in the literature (e.g., Shaw et al. 2012, 2013; Masetti et al. 2013) for 43% (128) of the 299 extragalactic sources.”
• MOJAVE. X. PARSEC-SCALE JET ORIENTATION VARIATIONS AND SUPERLUMINAL MOTION IN ACTIVE GALACTIC NUCLEI (2013, background): “Sbarufatti et al. (2005) foundz > 0.75 based on a lower limit to the host galaxy magnitude, and Shaw et al. (2013) derive a statistical upper limit ofz < 2.47 based on the absence of intergalactic absorption features.”
• 3FHL: The Third Catalog of Hard Fermi-LAT Sources (2017, methodology): “The associated blazars were optically classified as flatspectrum radio quasars (FSRQs), BL Lacs, and blazars of unknown types (BCUs, Shaw et al. 2012, 2013).”
• MOJAVE. XIII. PARSEC-SCALE AGN JET KINEMATICS ANALYSIS BASED ON 19 YEARS OF VLBA OBSERVATIONS AT 15 GHz (2016, background): “0300+470 (4C +47.08): No reliable spectroscopic redshift exists for this BL Lac is unknown Shaw et al. (2013), which contains an inward-moving feature (id = 1) at 0.8 mas from the core feature.”
• Fermi Large Area Telescope Fourth Source Catalog (2019, background): “…optical observations, which, for extragalactic objects, were also able to provide estimates of their cosmological distances (see, e.g., Shaw et al. 2013a, 2013b; Paggi et al. 2014; Landoni et al. 2015a, 2015b; Massaro et al. 2015a, 2015b; Ricci et al. 2015; Álvarez Crespo et al.…”
• THE FIRST FERMI-LAT CATALOG OF SOURCES ABOVE 10 GeV (2013, methodology): “8+4210), the values given by Ackermann et al. (2011b) violate lower limits reported by Shaw et al. (2013).”
• The Redshift of the BL Lac Object TXS 0506+056 (2018, methodology): “Optical spectroscopy obtained in previous years by Halpern et al. (2003), Shaw et al. (2013) and Landoni et al. (2013), and after the neutrino event, failed to determine the redshift of this object (Steele 2017; Soelen et al. 2017; Coleiro & Chaty 2017; Morokuma et al. 2017).”
• THE COSMIC EVOLUTION OF FERMI BL LACERTAE OBJECTS (2013, methodology): “To study this sample many different techniques have been employed to obtain redshift estimates or constraints for these blazars (see Rau et al. 2012; Shaw et al. 2013b,a), yielding the rather surprising detection of several BL Lacs up to redshift z≈2.”