Browsing by Author "D'Abrusco, R."

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    Extended X-Ray Emission around FR II Radio Galaxies: Hot Spots, Lobes, and Galaxy Clusters
    (2021) Jimenez-Gallardo, A.; Massaro, F.; Paggi, A.; D'Abrusco, R.; Prieto, M. A.; Pena-Herazo, H. A.; Berta, V; Ricci, F.; Stuardi, C.; Wilkes, B. J.; O'Dea, C. P.; Baum, S. A.; Kraft, R. P.; Forman, W. R.; Jones, C.; Mingo, B.; Liuzzo, E.; Balmaverde, B.; Capetti, A.; Missaglia, V; Hardcastle, M. J.; Baldi, R. D.; Morabito, L. K.
    We present a systematic analysis of the extended X-ray emission discovered around 35 FR II radio galaxies from the revised Third Cambridge Catalog (3CR) Chandra Snapshot Survey with redshifts between 0.05 and 0.9. We aimed to (i) test for the presence of extended X-ray emission around FR II radio galaxies, (ii) investigate whether the extended emission origin is due to inverse Compton (IC) scattering of seed photons arising from the cosmic microwave background (CMB) or thermal emission from an intracluster medium (ICM), and (iii) test the impact of this extended emission on hot-spot detection. We investigated the nature of the extended X-ray emission by studying its morphology and compared our results with low-frequency radio observations (i.e., similar to 150 MHz) in the TGSS and LOFAR archives, as well as with optical images from Pan-STARRS. In addition, we optimized a search for X-ray counterparts of hot spots in 3CR FR II radio galaxies. We found statistically significant extended emission (>3 sigma confidence level) along the radio axis of similar to 90% and in the perpendicular direction of similar to 60% of the galaxies in our sample. We confirmed the detection of seven hot spots in the 0.5-3 keV energy range. In the cases where the emission in the direction perpendicular to the radio axis is comparable to that along the radio axis, we suggest that the underlying radiative process is thermal emission from the ICM. Otherwise, the dominant radiative process is likely nonthermal IC/CMB emission from lobes. We found that nonthermal IC/CMB is the dominant process in similar to 70% of the sources in our sample, while thermal emission from the ICM dominates in similar to 15% of them.
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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.