Colin Carlile
Guest researcher
Southern African Large Telescope Spectroscopy of BL Lacs for the CTA project
Author
Summary, in English
In the last two decades, very-high-energy gamma-ray astronomy has reached maturity: over 200 sources have been detected, both Galactic and extragalactic, by ground-based experiments. At present, Active Galactic Nuclei (AGN) make up about 40% of the more than 200 sources detected at very high energies with ground-based telescopes, the majority of which are blazars, i.e. their jets are closely aligned with the line of sight to Earth and three quarters of which are classified as high-frequency peaked BL Lac objects. One challenge to studies of the cosmological evolution of BL Lacs is the difficulty of obtaining redshifts from their nearly featureless, continuum-dominated spectra. It is expected that a significant fraction of the AGN to be detected with the future Cherenkov Telescope Array (CTA) observatory will have no spectroscopic redshifts, compromising the reliability of BL Lac population studies, particularly of their cosmic evolution. We started an effort in 2019 to measure the redshifts of a large fraction of the AGN that are likely to be detected with CTA, using the Southern African Large Telescope (SALT). In this contribution, we present two results from an on-going SALT program focused on the determination of BL Lac object redshifts that will be relevant for the CTA observatory. © Copyright owned by the author(s) under the terms of the Creative Commons.
Department/s
- Lund Observatory - Has been reorganised
Publishing year
2022
Language
English
Publication/Series
Proceedings of Science
Volume
395
Document type
Conference paper
Topic
- Astronomy, Astrophysics and Cosmology
Keywords
- Cosmic rays
- Cosmology
- Gamma rays
- Observatories
- Telescopes
- Active galactic nuclei
- Blazars
- Cherenkov telescope arrays
- Ground based
- Ground-based telescopes
- Line of Sight
- Red shift
- Southern African Large Telescopes
- Very high energies
- Very-high-energy gamma-ray astronomies
- Active Galactic Nuclei
Status
Published
ISBN/ISSN/Other
- ISSN: 1824-8039