Related papers: Multi-wavelength Observations of VHE BL Lac Object…
Recent theoretical predictions of the lowest very high energy (VHE) luminosity of SN 1006 are only a factor 5 below the previously published H.E.S.S. upper limit, thus motivating further in-depth observations of this source. Deep…
Context: Part of the very high energy $\gamma$-ray radiation coming from extragalactic sources is absorbed through the pair production process on the extragalactic background light photons. Extragalactic magnetic fields alter the…
PKS 0548-322 (z=0.069) is a ``high-frequency-peaked'' BL Lac object and a candidate very high energy (VHE, E>100 GeV) gamma-ray emitter, due to its high X-ray and radio flux. Observations at the VHE band provide insights into the origin of…
The blazar Mrk 501 (z=0.034) was observed at very-high-energy (VHE, $E\gtrsim 100$~GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23-24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov telescopes. Data…
We observed the BL Lac object Markarian 421 with the X-ray satellite RXTE and the Whipple Air Cerenkov Telescope during a two week correlated X-ray/gamma-ray campaign in May 1996. Two dramatic outbursts with extremely rapid and strong flux…
Aims: Our aim is to study the production mechanism for very-high-energy (VHE; >100GeV) gamma-rays in distant active galactic nuclei (AGN) and use the observed VHE spectrum to derive limits on the Extragalactic Background Light (EBL). We…
The X-ray selected BL Lac PKS 2155-304 has been observed using the University of Durham Mark 6 very high energy gamma ray telescope during 1998. We find no evidence for TeV emission during these recent observations when the X-ray flux was…
Approximately 25 blazars are know to emit VHE (E>100 GeV) gamma rays. Understanding these powerful objects requires long-term, intense, monitoring observations since they exhibit strong, rapid and irregular variability across the entire…
We present the first multi-wavelength study of Mrk 501 including very-high-energy (VHE) gamma-ray observations simultaneous to X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). We use radio-to-VHE data from…
Mrk 421 and Mrk 501 are two close, bright and well-studied high-synchrotron-peaked blazars, which feature bright and persistent GeV and TeV emission. We use the longest and densest dataset of unbiased observations of these two sources,…
Only BL Lac objects have been detected as extragalactic sources of very high energy (E > 300 GeV) gamma rays. Using the Whipple Observatory Gamma-ray Telescope, we have attempted to detect more BL Lacs using three approaches. First, we have…
In this letter I report the Fermi Large Area Telescope (LAT) detection of Very High Energy (VHE; E>100 GeV) gamma-ray emission from the BL Lac object RBS 0970. 5.3 years of LAT observations revealed the presence of 3 VHE photon events…
We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1 which includes, among other instruments, MAGIC, VERITAS, Whipple…
Very high-energy (VHE, E\,$>$\,100\,GeV) $\gamma$-ray data are a valuable input for multi-wavelength and multi-messenger (e.g. combination with neutrino data) studies. We aim at the conservation and homogenization of historical, current,…
The study of high-energy gamma-ray emission from gamma-ray bursts (GRBs) involves complex synchrotron radiation and synchrotron self-Compton scattering (SSC) mechanisms with multiple parameters exhibiting a wide distribution. Recent…
The BL Lac object RGB J0152+017 (z = 0.080) was predicted to be a very high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio fluxes. We report recent observations of this source made in late October and November…
We present observations of the gamma-ray blazar Markarian 501 between April 17 and May 5, 2009, with the Whipple 10-m telescope, VERITAS, the Fermi Large Area Telescope (LAT), Swift and RXTE as part of a 4.5-month multi-wavelength campaign.…
We study the possible detection of and properties of very high-energy (VHE) gamma-ray emission (in the energy band above 100 GeV) from high redshift sources. We report on the detection of VHE gamma-ray flux from blazars with redshifts…
Among the blazars whose emission has been detected up to very-high-energy (VHE; 100 GeV < E < 100 TeV) gamma rays, intermediate synchrotron-peaked BL Lacs (IBLs) are quite rare. The IBL B2 1811+31 (z = 0.117) exhibited intense flaring…
We report results from a multi-wavelength monitoring campaign on Mrk 421 over the period of 2003-2004. The source was observed simultaneously at TeV and X-ray energies, with supporting observations frequently carried out at optical and…