Target of opportunity observations of blazars with H.E.S.S.

  title={Target of opportunity observations of blazars with H.E.S.S.},
  author={M. Cerruti and Markus Bottcher and Nachiketa Chakraborty and I. D. Davids and Matthias Fussling and Felix Jankowsky and J.-P. Lenain and Manuel Meyer and Heike Prokoph and Stefan J. Wagner and D. N. Zaborov and Michael Zacharias and The H.E.S.S. Collaboration},
The very high energy (VHE, E > 100 GeV) sky is dominated by blazars, radio-loud active galactic nuclei whose relativistic jet is closely aligned with the line of sight. Blazars are characterized by rapid variability at all wavelengths and thus an important part of the H.E.S.S. blazar program is devoted to target of opportunity (ToO) observations. H.E.S.S. triggers blazar ToOs on the basis of publicly available blazar observations at longer wavelengths (optical, X-rays, and γ-rays), from private… Expand

Figures from this paper

Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE γ-ray observations with H.E.S.S.
The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV <  E <  100 GeV) γ-ray band, which is continuously monitored with Fermi-LAT. During twoExpand
Monitoring the Extragalactic High Energy Sky
Blazars are jetted active galactic nuclei with a jet pointing close to the line of sight, hence enhancing their intrinsic luminosity and variability. Monitoring these sources is essential in order toExpand
The VHE γ-Ray View of the FSRQ PKS 1510-089
The flat spectrum radio quasar PKS 1510-089 is a monitored target in many wavelength bands due to its high variability. It was detected as a very-high-energy (VHE) γ-ray emitter with H.E.S.S. inExpand
H.E.S.S. searches for TeV gamma-rays associated to high-energy neutrinos
The detection of an astrophysical flux of high-energy neutrinos by IceCube is a major step forward in the search for the origin of cosmic rays, as this emission is expected to originate in hadronicExpand
Transient phenomena in the high energy sky
In this thesis I explore some of the brightest transient phenomena we observe in the highnenergy sky. I consider some of the observational difficulties we encounter in studying these highly variableExpand
Active galactic nuclei horizons from the gamma-ray perspective
Abstract Recent results in the field of high energy active galactic nuclei (AGN) astrophysics, benefiting from improvements to gamma-ray instruments and observational strategies, have revealed aExpand
Search for high-energy neutrino emission from Mrk 421 and Mrk 501 with the ANTARES neutrino telescope
ANTARES is the largest high-energy neutrino telescope in the Northern Hemisphere. This contribution presents the results of a search, based on the ANTARES data collected over 17 months betweenExpand
H.E.S.S. highlights
The H.E.S.S. collaboration continues to run an array of five Imaging Atmospheric Cherenkov Telescopes to observe the Southern sky in very high energy gamma-rays. In this presentation, recentExpand


Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopes
Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energyExpand
Very-high-energy blazars: updates from VERITAS observations and multi-wavelength campaigns
VERITAS is an array of four 12-m atmospheric Cherenkov telescopes, designed to observe the very-high-energy (VHE; E $\geq$100 GeV) sky. Since 2007, it has detected more than 20 extra-galacticExpand
AGN observations with a less than 100 GeV threshold using H.E.S.S. II
The recent addition of the 28 m Cherenkov telescope (CT5) to the H.E.S.S. array extended the experiment’s sensitivity towards low energies. The lowest energy threshold is obtained using monoscopicExpand
Detection of very-high-energy gamma rays from the most distant and gravitationally lensed blazar QSO B0218+357 using the MAGIC telescope system
QSO B0218+357 is a blazar located at a cosmological redshift of z=0.944. It is gravitationally lensed by a spiral galaxy at a redshift of z=0.68. The blazar and its lens are well studied in the radioExpand
On the redshift of the gamma-ray blazar PKS 0447-439: Optical spectroscopy using Gemini observations with high S/N ratio
The BL-Lac blazar PKS 0447-439 was detected at very high energy gamma-rays by HESS following the discovery by Fermi-LAT. The lack of both emission and absorption lines in BL-Lacs make the estimationExpand
Very High Energy γ-Rays from the Universe's Middle Age: Detection of the z = 0.940 Blazar PKS 1441+25 with MAGIC
The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5 {\sigma} using the MAGIC telescopes. Together with theExpand
Gamma-Rays from the Quasar PKS 1441+25: Story of an Escape
Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the Universe. The detection ofExpand
A high performance likelihood reconstruction of γ-rays for imaging atmospheric Cherenkov telescopes
Abstract We present a sophisticated γ -ray likelihood reconstruction technique for imaging atmospheric Cerenkov telescopes. The technique is based on the comparison of the raw Cherenkov camera pixelExpand
The ultraviolet excess of quasars 3: The highly polarized quasars PKS 0736+017 and PKS 1510-089
Ultraviolet/optical/infrared spectrophotometry of the highly-polarized quasars (HPQ's) PKS 0736+017 and PKS 1510-089 is analyzed. A blazar continuum component like that in BL Lac objects (e.g. withExpand
Very high energy (VHE) gamma-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+ 21 (4C 21.35, z = 0.432) was detected with the MAGIC Cherenkov telescopes during a short observationExpand