Seminar by Stefano Marchesi, Università di Bologna / INAF-OAS / Clemson
In this talk, I will present the results of a multi-wavelength study of blazars selected from the 5th ROMABZCAT catalog, aimed at determining how effectively the blazars X-ray emission can be used to trace their Very High Energy (VHE, i.e., above 20 GeV) emission.
To do so, we selected a subsample of over 1000 objects that are not detected in the Fermi-LAT 14-year source catalog (4FGL) while at the same time having at least one counterpart in one of the three main archival X-ray catalogs, which is, the fourth release of the XMM-Newton Survey Science Catalogue, the second release of the Chandra Source Catalog, and the second Swift-XRT X-ray Point Source catalog of detections by XRT, or in the recently released eROSITA-DE Data Release 1 catalog.
A large number of sources, mostly BL Lacs or BL Lacs with host-galaxy contribution to the spectral energy distribution, have large synchrotron peak frequency and X-ray to radio flux ratio, two properties that characterize the vast majority of known TeV emitters. With respect to these known TeV emitters, our targets have X-ray fluxes ~1 order of magnitude fainter. We then computed the 0.2-12 keV and 20 GeV - 300 TeV fluxes for the known 5BZCAT TeV emitters, and determined the existence of a direct correlation between X-ray and TeV fluxes in the BL Lacs population.
We used this trend to estimate the VHE flux of our targets, and found a promising sample of sources for follow-up observations with current or future, more sensitive, Cherenkov telescopes, first and foremost the Cherenkov Telescope Array Observatory. In the final part of the talk, I will discuss the different ways in which we are further analyzing these promising targets.
Host: Jooyun Woo