Highlights from the VERITAS AGN Observation Program

Benbow, W.

doi:10.22323/1.236.0821

Cited by 21 publications

(24 citation statements)

References 28 publications

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“…To maximize the scientific output of the blazar program, VERITAS now focuses the majority of its observational time on deep exposures of a select group of sources. This program is discussed in more detail elsewhere in these proceedings [16], here we will focus on a few recent highlights and ongoing studies.…”

Section: Extragalactic Sciencementioning

confidence: 99%

Science Highlights from VERITAS

Staszak¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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VERITAS is a ground-based array of four 12-meter telescopes near Tucson, Arizona and is one of the world's most sensitive detectors of very high energy (VHE: >100 GeV) gamma rays. VER-ITAS has a wide scientific reach that includes the study of extragalactic and Galactic objects as well as the search for astrophysical signatures of dark matter and the measurement of cosmic rays. In this presentation, we will summarize the current status of the VERITAS observatory and present some of the scientific highlights since 2013.

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Section: Extragalactic Sciencementioning

confidence: 99%

Science Highlights from VERITAS

Staszak¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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“…Later on it was detected in the gamma-ray band with Fermi-LAT in the energy range E > 100 MeV [19]. MAGIC and VERITAS reported the detection at E > 100 GeV in [16,20,21].…”

Section: Ngc 1275mentioning

confidence: 98%

Spectacular Flares of the Radio Galaxy NGC 1275 measured with MAGIC

Glawion¹,

Nigro²,

Pfrang³

et al. 2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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We report on the detection of flaring activity from the prominent Fanaroff-Riley I radio galaxy NGC 1275 located in the Perseus cluster of galaxies in the very-high-energy gamma-ray band.The observations were performed with the MAGIC telescopes between 2016 and 2017 over several months. During this time period, the mean flux above 100 GeV was measured to be roughly ten times brighter than during previous observations. The night-by-night light curve above 100 GeV shows several peaks indicating flux-doubling time-scales of shorter than one day much smaller than the monthly time-scale previously detected by MAGIC. The brightest flux, observed around December 2016 and January 2017, reached 1.75 times the flux from the Crab Nebula, i.e. was about sixty times brighter than the average flux of the previous years. The spectral energy distribution measured up to > 1 TeV shows a curved shape unlike the previously measured simple power-law. The angle between the jet-axis and the line-of sight of NGC 1275 was formerly found to be 30-55 degree in the radio band excluding strong Doppler boosting of the emitted radiation towards the observer. The fast TeV flux variability and the spectral behaviour observed from a non-blazar object challenge current standard theoretical models and therefore, provide new and fascinating insights into the gamma-ray production and emission mechanism of active galactic nuclei. In the conference, we present the observational results and discuss possible physical processes responsible for the flaring events.

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“…Fermi observations suggest that the GeV photon flux of the source has been continuously rising since then (see Section 4 for details). In 2009, the source was also detected at TeV energies [49,50]. In the end of 2016 and early 2017, the source has been through a dramatic flaring activity.…”

Section: Observations Of the Tev Emitting Radio Galaxiesmentioning

confidence: 99%

Radio Galaxies - The TeV Challenge

Rani¹

2018

Preprint

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Over the past decade, our knowledge of the γ-ray sky has been revolutionized by ground-and space-based observatories by detecting photons up to several hundreds of tera-electron volt (TeV) energies. A major population of the γ-ray bright objects are active galactic nuclei (AGN) with their relativistic jets pointed along our line-of-sight. Gamma-ray emission is also detected from nearby mis-aligned AGN such as radio galaxies. While the TeV-detected radio galaxies (T eV Rad) only form a small fraction of the γ-ray detected AGN, their multi-wavelength study offers a unique opportunity to probe and pinpoint the high-energy emission processes and sites. Even in the absence of substantial Doppler beaming T eV Rad are extremely bright objects in the TeV sky (luminosities detected up to 10 45 erg s −1 ), and exhibit flux variations on timescales shorter than the event-horizon scales (flux doubling timescale less than 5 minutes). Thanks to the recent advancement in the imaging capabilities of high-resolution radio interferometry (millimeter very long baseline interferometry, mm-VLBI), one can probe the scales down to less than 10 gravitational radii in T eV Rad, making it possible not only to test jet launching models but also to pinpoint the high-energy emission sites and to unravel the emission mechanisms. This review provides an overview of the high-energy observations of T eV Rad with a focus on the emitting sites and radiation processes. Some recent approaches in simulations are also sketched. Observations by the near-future facilities like Cherenkov Telescope Array, short millimeter-VLBI, and high-energy polarimetry instruments will be crucial for discriminating the competing high-energy emission models.

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Highlights from the VERITAS AGN Observation Program

Cited by 21 publications

References 28 publications

Science Highlights from VERITAS

Science Highlights from VERITAS

Spectacular Flares of the Radio Galaxy NGC 1275 measured with MAGIC

Radio Galaxies - The TeV Challenge

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