Prospects for gamma-ray observations of narrow-line Seyfert 1 galaxies with the Cherenkov Telescope Array

Abstract

Gamma-ray emitting narrow-line Seyfert 1 (γ-NLS1) galaxies possibly harbour relatively low-mass black holes (10 6 -10 8 M ⊙ ) accreting close to the Eddington limit, and share many characteristics with their sibling sources, flat-spectrum radio quasars. Although they have been detected in the MeV-GeV band with Fermi-LAT, they have never been seen in the very high energy band with current imaging atmospheric Cherenkov telescopes (IACTs). Thus, they are key targets for the next-generation IACT, the Cherenkov Telescope Array (CTA). In a previous work we selected, by means of extensive simulations, the best candidates for a prospective CTA detection (SBS 0846+513, PMN J0948+0022, and PKS 1502+036) taking into account the effects of both the intrinsic absorption (approximated with a cut-off at 30 GeV), and the extra-galactic background light on the propagation of γ-rays. In this work we simulate the spectra of these three sources by adopting more realistic broad-line region (BLR) absorption models. In particular, we consider the detailed treatment of γ-γ absorption in the radiation fields of the BLR as a function of the location of the γ-ray emission region with parameters inferred from observational constraints. We find that, due to the energy range extent and its sensitivity, CTA is particularly well suited to locate the γ-ray emitting region in γ-NLS1. In particular CTA will be able not only to distinguish whether the γ-ray emitting region is located inside or outside the BLR, but also where inside the BLR it may be.

SDSS J094635.06+101706.1: a redshift one, very radio-loud, γ-ray emitting narrow-line Seyfert 1 galaxy

“…With Fermi/LAT, it was discovered that a few of the jetted NLS1 galaxies emit luminous γ-ray radiation, highly variable in some cases, and E-mail: yaosu@pku.edu.cn independently confirming the presence of powerful jets in some NLS1 galaxies (Abdo et al 2009b). Meanwhile, about 15 γ-ray emitting NLS1s have been identified (Abdo et al 2009a;Abdo et al 2009a;Foschini 2011;D'Ammando et al 2012;D'Ammando et al 2015;Yao et al 2015;Yang et al 2018;Paliya et al 2018;Lähteenmäki et al 2018; see Komossa 2018 andRomano et al 2018 for reviews).…”

A Cloud-based Architecture for the Cherenkov Telescope Array Observation Simulations: Optimization, Design, and Results

“…The application of the energy dispersion matrix for sources requiring a detailed spectral treatment in the softer energies (e.g. E 500 GeV) and will be shown (Romano et al 2018;Lamastra et al 2019) to increase the run time by a factor of 5-10.…”

Gamma-ray emitting narrow-line Seyfert 1 galaxies: Past, present, and future

“…Red data points refer to the 2013 April-July γ-ray flare of the source, whereas, blue stars correspond to the simulated fluxes for 50 hr of CTA-North exposure. The Fermi-LAT and CTA data are adopted from and Romano et al (2018), respectively. The black dashed line represents the input model used for the simulation whose details can be found at Romano et al (2018).…”

“…The Fermi-LAT and CTA data are adopted from and Romano et al (2018), respectively. The black dashed line represents the input model used for the simulation whose details can be found at Romano et al (2018).…”