Hunting Distant BL Lacertae Objects with the Photometric Technique Using Swift and SARA
Abstract
BL Lacertae objects represent a large fraction (22%) of γ-ray sources in the Third Fermi Large Area Telescope catalog (3FGL). Nearly half of the BL Lac object population remains without a redshift because of their featureless optical spectra. We aim to increase the number of BL Lac objects with a redshift measurement by using the photometric technique. For this work, we have used six Swift-UVOT filters and SDSS g', r', i', and z' optical filters mounted on the 0.65 m SARA-CTIO located in Chile and the 1.0 m SARA-ORM in the Canary Islands. A sample of 45 sources was selected from the 3FGL catalog for which photometry was performed in 10 optical and UV filters to obtain redshift measurements. We found three sources with z > 1.3, while reliable upper limits have been provided for 17 sources. The results presented here bring the total number of high-z (z > 1.3) BL Lac objects to 29.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2020
- DOI:
- 10.3847/1538-4357/ab96c4
- arXiv:
- arXiv:2002.07740
- Bibcode:
- 2020ApJ...898...18R
- Keywords:
-
- Active galactic nuclei;
- Active galaxies;
- Blazars;
- High energy astrophysics;
- High-redshift galaxies;
- 16;
- 17;
- 164;
- 739;
- 734;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- doi:10.3847/1538-4357/ab96c4