16 pages, 2 figures, 4 tables
The extragalactic γ-rays sky observed by Fermi-Large Area Telescope (LAT) is dominated by blazars. In the fourth release of the Fermi-LAT Point Source Catalog (4FGL), are sources showing a multifrequency behavior similar to that of blazars but lacking an optical spectroscopic confirmation of their nature known as Blazar Candidate of Uncertain type (BCUs). We aim at confirming the blazar nature of BCUs and test if new optical spectroscopic observations can reveal spectral features, allowing us to get a redshift estimate for known BL Lac objects. We also aim to search for and discover changing-look blazars (i.e., blazars that show a different classification at different epochs). We carried out an extensive search for optical spectra available in the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Data Release 5 (DR5) archive. We selected sources out of the 4FGL catalog, the list of targets from our follow-up spectroscopic campaign of unidentified or unassociated γ-ray sources, and the multifrequency catalog of blazars: the Roma-BZCAT. We selected a total of 392 spectra. We also compare some of the LAMOST spectra with those available in the literature. We classified 20 BCUs confirming their blazar-like nature. Then we obtained 15 new redshift estimates for known blazars. We discovered 26 transitional (i.e., changing-look) blazars that changed their classification. Finally, we were able to confirm the blazar-like nature of six BL Lac candidates. All remaining sources analyzed agree with previous classifications. BL Lac objects are certainly the most elusive type of blazars in the γ-ray extragalactic sky.
23 pages, 19 figures, 2 tables
Accepted for publication in ApJ. 27 pages, 18 figures
Accepted for publication in MNRAS. 16 pages, 11 figures, 1 table
13 pages, 12 figures, 3 tables; accepted for publication on Astronomy and Astrophysics
27 pages, 18 figures, 5 tables; accepted for publication in MNRAS
17 pages, 2 figures. Readers not interested in the detailed derivations can skip to Appendix A, which simply summarizes the key equations derived
8 pages, 3 figures, submitted to MNRAS. Comments welcome
Accepted for publication in ApJ, 15 pages, 5 figures, 4 tables
5 pages, 5 figures. arXiv admin note: text overlap with arXiv:2006.06702
15 pages, 7 figures and 4 tables, Accepted for publication in Astrophysics and Space Science
16 pages, 13 figures. Accepted for publication by MNRAS
Accepted for publication in A&A
Accepted for publication by ApJS. Data may be downloaded here: this http URL
Ph.D. thesis in Astronomy & Astrophysics (373 total pages; 312 pages of chapters & appendices with 113 figures & 19 tables), The Pennsylvania State University, Advisor: Randall L. McEntaffer. Defended 12/18/2020
PhD thesis supervised by C. Venter and A. K. Harding and accepted by the North-West University (Potchefstroom) South Africa in February 2021, 114 pages, 50 figures. Abstract abridged
11 pages, 6 figures, accepted for publication to PASP
Submitted to MNRAS, 9 pages and 7 figures
Accepted for publication in MNRAS, 18 pages, 9 figures, 2 tables, 1 equation
36 Pages, 6 Figures, AJ in press
Accepted for publications by the MNRAS
10 pages, 3 Tables, 9 Figures; Submitted to ApJ; Comments are welcome
10 pages, 9 figures
35 pages, 27 figures
47 pages, 12 figures
40 pages, 51 figures, submitted to MNRAS
There are 20 pages and 24 figures
19 Pages 08 Figures 01 Tables
18 pages, 6 figures, in "Applied and computational historical astronomy", ed. G. Wolfschmidt, Nuncius Hamburgensis, Beitr\"age zur Geschichte der Naturwissenschaften, vol 51
Accepted to ApJ; 20 pages, 11 figures, 4 tables
31 pages, 3 figures, Preprint of a chapter of the book 'Millisecond Pulsars', of the Astrophysics and Space Science Library (ASSL) series edited by Sudip Bhattacharyya, Alessandro Papitto and Dipankar Bhattacharya
37 pages. Published as part of the IJMPD special issue "Modified Gravity: Progresses and Outlook of Theories, Numerical Techniques and Observational Tests" edited by Baojiu Li and Kazuya Koyama. Submitted to arXiv after end of embargo period
26 pages, 9 figures. Accepted for publication in the Astrophysical Journal
6 pages, 2 figures
6 pages, 2 figures