skip to main content

SciTech ConnectSciTech Connect

Title: Spectroscopy of optically selected BL Lac objects and their γ-ray emission

We present Very Large Telescope optical spectroscopy of nine BL Lac objects of unknown redshift belonging to the list of optically selected radio-loud BL Lac candidates. We explore their spectroscopic properties and possible link with gamma-ray emission. From the new observations we determine the redshifts of four objects from faint emission lines or from absorption features of their host galaxies. In three cases we find narrow intervening absorptions from which a lower limit to the redshift is inferred. For the remaining two featureless sources, lower limits to the redshift are deduced from the absence of spectral lines. A search for γ counterpart emission shows that six out of the nine candidates are Fermi γ-ray emitters and we find two new detections. Our analysis suggests that most of the BL Lac objects still lacking redshift information are most likely located at high redshifts.
Authors:
; ; ;  [1] ;  [2] ; ;  [3]
  1. Università degli Studi dell'Insubria, Via Valleggio 11, I-22100 Como (Italy)
  2. INAF-Osservatorio Astronomico di Padova, Vicolo dell Osservatorio 5, I-35122 Padova (Italy)
  3. INAF-Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (Italy)
Publication Date:
OSTI Identifier:
22340061
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; BL LACERTAE OBJECTS; DETECTION; DISTANCE; EMISSION; GALAXIES; GAMMA RADIATION; RADIO TELESCOPES; RED SHIFT; SPECTROSCOPY