Speaker
Description
1ES 0647+250 is a seemingly distant high-frequency-peaked BL Lac (HBL) object. Its redshift is uncertain but a recent 2023 estimate from the MAGIC Collaboration places 1ES 0647+250 at a redshift of 0.45 +/– 0.05, which is in agreement with most estimates and lower limits in the literature. A spectrum taken with the Keck Echellette Spectrograph and Imager on 2022/12/24 shows no spectral lines from the host galaxy. According to TeVCat, adopting a redshift of 0.45 would place 1ES 0647+250 among the most distant HBLs observed at TeV energies. Two VHE flares were observed with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) – in December 2012 and December 2020. We build multi-wavelength SEDs of the flares with VERITAS, Fermi-LAT, Swift-XRT, and Swift-UVOT data, and model the spectral energy distributions (SEDs) with a synchrotron self-Compton model using a tool called Bjet_MCMC. We discuss the SED modeling results and implications in this presentation.
