VHE gamma-ray detection of FSRQ QSO B1420+326 and modeling of its enhanced broadband state in 2020

Abstract

Context. QSO B1420+326 is a blazar classified as a flat-spectrum radio quasar (FSRQ). At the beginning of the year 2020, it was found to be in an enhanced flux state and an extensive multiwavelength campaign allowed us to trace the evolution of the flare. Aims. We search for very high-energy (VHE) gamma-ray emission from QSO B1420+326 during this flaring state. We aim to characterize and model the broadband emission of the source over different phases of the flare. Methods. The source was observed with a number of instruments in radio, near-infrared, optical (including polarimetry and spectroscopy), ultraviolet, X-ray, and gamma-ray bands. We use dedicated optical spectroscopy results to estimate the accretion disk and the dust torus luminosity. We performed spectral energy distribution modeling in the framework of combined synchrotron-self-Compton and external Compton scenario in which the electron energy distribution is partially determined from acceleration and cooling processes. Results. During the enhanced state, the flux of both SED components of QSO B1420+326 drastically increased and the peaks were shifted to higher energies. Follow-up observations with the MAGIC telescopes led to the detection of VHE gamma-ray emission from this source, making it one of only a handful of FSRQs known in this energy range. Modeling allows us to constrain the evolution of the magnetic field and electron energy distribution in the emission region. The gamma-ray flare was accompanied by a rotation of the optical polarization vector during a low-polarization state. Also, a new superluminal radio knot contemporaneously appeared in the radio image of the jet. The optical spectroscopy shows a prominent FeII bump with flux evolving together with the continuum emission and a MgII line with varying equivalent width.

Proton acceleration in thermonuclear nova explosions revealed by gamma rays

“…The data were analyzed using the MAGIC Analysis and Reconstruction Software, MARS [46]. A dedicated low-energy procedure with a special signal extraction and image cleaning, the so-called MaTaJu method, was applied (see [47] and references therein). Further processing of the data, including the image parameterization, the direction and energy reconstruction and gammahadron separation, were applied following the standard MARS analysis chain.…”

MAGIC Upper Limits on the VHE emission from Flat Spectrum Radio Quasars

“…This makes them ideal candidates for follow-up observations at VHE following high flux states at lower energy bands. In total, nine FSRQs which have been detected in the VHE energy range so far: 3C 279 [13], 4C +21.35 [4], PKS 1510-089 [16], PKS 1441+25 [2], S30218+35 [3], TON 0599 [20], PKS 0736+017 [17], B2 1420+32 [19] and PKS 0346-27 [27] In this contribution, we present the VHE -ray observation, their data analysis and the corresponding results of the nine FSRQs, namely TXS 0025+197, B2 0234+28, AO 0235+146, 4C55.17, OP 313, CTA 102, B2 2234+28A, TXS 2241+406 and 3C 454.3. We used the data collected by the MAGIC [5], Fermi-LAT [7] data simultaneous to the MAGIC observations and optical data from the KVA [25].…”