Browsing by Author "Chavushyan, V"

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    Multiwavelength monitoring of the nucleus in PBC?J2333.9-2343: the giant radio galaxy with a blazar-like core
    (2023) Hernandez-Garcia, L.; Panessa, F.; Bruni, G.; Bassani, L.; Arevalo, P.; Patino-Alvarez, V. M.; Tramacere, A.; Lira, P.; Sanchez-Saez, P.; Bauer, F. E.; Chavushyan, V; Carraro, R.; Forster, F.; Arancibia, A. M. Munoz; Ubertini, P.
    PBC J2333.9-2343 is a giant radio galaxy at z = 0.047 with a bright central core associated to a blazar nucleus. If the nuclear blazar jet is a new phase of the jet activity, then the small orientation angle suggests a dramatic change of the jet direction. We present observations obtained between 2018 September and 2019 January (cadence larger than three days) with Effeslberg, SMARTS-1.3m, ZTF, ATLAS, Swift, and Fermi-LAT, and between 2019 April and 2019 July (daily cadence) with SMARTS-1.3 m and ATLAS. Large (>2 x) flux increases are observed on time-scales shorter than a month, which are interpreted as flaring events. The cross correlation between the SMARTS-1.3 m monitoring in the NIR and optical shows that these data do not show significant time lag within the measured errors. A comparison of the optical variability properties between non-blazars and blazars AGN shows that PBC J2333.9-2343 has properties more comparable to the latter. The SED of the nucleus shows two peaks, that were fitted with a one-zone leptonic model. Our data and modelling show that the high energy peak is dominated by External Compton from the dusty torus with mild contribution from Inverse Compton from the jet. The derived jet angle of 3 deg is also typical of a blazar. Therefore, we confirm the presence of a blazar-like core in the centre of this giant radio galaxy, likely a Flat Spectrum Radio Quasar with peculiar properties.
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    Optical spectroscopic observations of gamma-ray blazar candidates. X. Results from the 2018-2019 SOAR and OAN-SPM observations of blazar candidates of uncertain type
    (2020) de Menezes, R.; Amaya-Almazan, R. A.; Marchesini, E. J.; Pena-Herazo, H. A.; Massaro, F.; Chavushyan, V; Paggi, A.; Landoni, M.; Masetti, N.; Ricci, F.; D'Abrusco, R.; La Franca, F.; Smith, Howard A.; Milisavljevic, D.; Tosti, G.; Jimenez-Bailon, E.; Cheung, C. C.
    The fourth Fermi Large Area Telescope Source Catalog (4FGL) lists over 5000. -ray sources with statistical significance above 4s. About 23% of the sources listed in this catalog are unidentified/unassociated. -ray sources while 26% of the sources are classified as blazar candidates of uncertain type (BCUs), lacking optical spectroscopic information. To probe the blazar nature of candi- date counterparts of UGSs and BCUs, we started our optical spectroscopic follow up campaign in 2012, which up to date account for more than 350 observed sources. In this paper, the tenth of our campaign, we report on the spectroscopic observations of 37 sources, mostly BCUs, whose observations were carried out predominantly at the Observatorio Astronomico Nacional San Pedro Martir and the Southern Astrophysical Research Observatory between August 2018 and September 2019. We confirm the BL Lac nature of 27 sources and the flat spectrum radio quasar nature of three sources. The remaining ones are classified as six BL Lacs galaxy-dominated and one normal galaxy. We were also able to measure the redshifts for 20 sources, including 10 BL Lacs. As in previous analyses, the largest fraction of BCUs revealed to be BL Lac objects.