# ICRC2015

July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

## Discovery of very-high-energy gamma-ray emission from a hard-X-ray bright HBL RX J1136.5+6737

Jul 30, 2015, 11:30 AM
15m
Yangtze 1 (World Forum)

### Yangtze 1

#### World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Oral contribution GA-EX

### Speaker

Dr Masaaki Hayashida (Institute for Cosmic-Ray Research, University of Tokyo)

### Description

RX J1136.5+6737 (z=0.1342) is a hard X-ray bright high-peaked frequency BL Lac object as listed in the MAXI 3-year catalog as well as the Swift-BAT catalog. The source has also been detected by Fermi-LAT with a hard photon index of $1.68\pm0.12$, and belongs to the first Fermi-LAT catalog of $>10$ GeV sources, showing bright (photon flux = $11.7\times10^{-11}$ ph cm$^{-2}$ s$^{-1}$) emission above 10 GeV. MAGIC observed the source for about 30 hours in 2014 and discovered very-high-energy (VHE) gamma-ray emission from the source with $>5\sigma$ significance. The averaged flux measured by MAGIC during the 2014 observations corresponds to about 1.5% of the Crab Nebula flux at energies above 200 GeV without significant variability. The measured spectrum shows evidence of extending into the TeV energy range, even though most extragalactic background light models predict the distance of z=0.1342 is beyond the "Cosmic gamma-ray horizon" at 1 TeV. Along with the MAGIC observations, we coordinated simultaneous multi-band observations in X-ray and UV bands by Swift, and in optical-IR bands by ground-based telescopes such as Kanata and KVA. In this contribution, the first results of the MAGIC discovery of VHE emission from RX J1136.5+6737 will be reported. We will also discuss origins of the gamma-ray emission with a broad-band spectral energy distribution using our emission model, which takes into account secondary gamma-ray photons produced from cascades induced by ultra-high-energy gamma-ray or protons propagating through intergalactic space.
Registration number following "ICRC2015-I/" 81 MAGIC

### Primary author

Dr Masaaki Hayashida (Institute for Cosmic-Ray Research, University of Tokyo)

### Co-authors

Dr Hajime Takami (KEK) Dr Ryosuke ITOH (Hiroshima University) Mr Yusuke Konno (Kyoto University)

### Presentation materials

There are no materials yet.