Optical spectroscopy of the gamma-ray bright blazars PKS 0447-439 and PMN J0630-24

Abstract

The large majority of sources detected by the Fermi Gamma-ray Space Telescope are blazars, belonging in particular to the blazar subclass of BL Lacertae objects (BL Lacs). BL Lacs often have featureless optical spectra, which make it difficult and sometimes impossible to determine their redshifts. This presents a severe impediment for the use of BL Lacs to measure the spectrum of the extragalactic background light through its interaction with high-energy gamma-ray photons. I present here high-quality optical spectroscopy of two of the brightest gamma-ray blazars, namely, PKS 0447-439 and PMN J0630-24. The medium-resolution and high signal-to-noise ratio optical spectra show clear absorption lines, which place these BL Lacs at relatively high redshifts of z>=1.246 for PKS 0447-439 and z>=1.238 for PMN J0630-24.

4 pages, 2 figures, accepted by MNRAS Letters

References in corpus (6)

• Fermi Large Area Telescope Second Source Catalog
• Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
• BL Lacertae objects beyond redshift 1.3 - UV-to-NIR photometry and photometric redshift for Fermi/LAT blazars
• The Sedentary Survey of Extreme High Energy Peaked BL Lacs III. Results from Optical Spectroscopy
• On the relationship between BL Lacertae objects and radio galaxies
• Estimating the redshift of PKS 0447-439 through its GeV-TeV emission

Cited by in corpus (15)

• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• The Extragalactic Background Light and the Gamma-ray Opacity of the Universe
• Spectroscopy of High Energy BL Lac Objects with X-shooter on the VLT
• Gamma-rays from Blazars and the Extragalactic Background Light
• TeV gamma rays from blazars beyond z=1?
• Discovery of TeV gamma-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift
• Redshift determination of the BL Lac object 3C66A by the detection of its host galaxy cluster at $z=0.340$
• The BL-Lac gamma-ray blazar PKS 0447-439 as a probable member of a group of galaxies at z=0.343
• Estimating the redshift of PKS 0447-439 through its GeV-TeV emission
• New high-z BL Lacs using the photometric method with Swift and SARA
• Emitting Electron Spectra and Acceleration Processes in the Jet of PKS 0447-439
• Very-high-energy gamma-ray emission from high-redshift blazars
• On the redshift of the blazar PKS0447-439
• Cosmic connections: from cosmic rays to gamma rays, to cosmic backgrounds and magnetic fields
• The H.E.S.S. Extragalactic Sky