Refine
Has Fulltext
- no (64)
Language
- English (64)
Is part of the Bibliography
- yes (64)
Keywords
- gamma rays: general (22)
- radiation mechanisms: non-thermal (17)
- ISM: supernova remnants (14)
- cosmic rays (11)
- galaxies: active (10)
- gamma rays: galaxies (10)
- acceleration of particles (8)
- ISM: clouds (6)
- astroparticle physics (6)
- gamma rays: ISM (6)
- gamma rays: stars (6)
- gamma-rays: galaxies (5)
- galaxies: jets (4)
- BL Lacertae objects: individual: PKS 2155-304 (3)
- X-rays: binaries (3)
- BL Lacertae objects: general (2)
- ISM: individual objects: G338.3-0.0 (2)
- binaries: general (2)
- errata, addenda (2)
- pulsars: general (2)
- pulsars: individual: PSR B0833-45 (2)
- relativistic processes (2)
- stars: massive (2)
- surveys (2)
- BL Lacertae objects: individual (Mrk 501) (1)
- BL Lacertae objects: individual (PG 1553+113) (1)
- BL Lacertae objects: individual: 1ES 1312-423 (1)
- BL Lacertae objects: individual: 1ES 2322-409 (1)
- BL Lacertae objects: individual: AP Librae (1)
- BL Lacertae objects: individual: PKS 0301-243 (1)
- BL Lacertae objects: individual: SHBL J001355.9-185406 (1)
- BL Lacertae objects: individual: lES 0229+200 (1)
- BL Lacertae objects: individual: lES 1101-232 (1)
- Galaxy: center (1)
- Galaxy: general (1)
- ISM (1)
- ISM: individual objects (RX J1713.7-3946, G347.3-0.5) (1)
- ISM: individual objects (SNR G338.3-0.0, SNR G338.5+0.1) (1)
- ISM: individual objects: Crab nebula (1)
- ISM: individual objects: HESS J1832-093 (1)
- ISM: individual objects: Puppis A (1)
- ISM: individual objects: SNR G1.9+0.3 (1)
- ISM: individual objects: SNR G22.7-0.2 (1)
- ISM: individual objects: SNR G330.2+1.0 (1)
- ISM: jets and outflows (1)
- ISM: magnetic fields (1)
- X-rays: general (1)
- X-rays: individuals: Circinus X-1 (1)
- X-rays: individuals: G15.4+0.1 (1)
- X-rays: individuals: GRS 1915+105 (1)
- X-rays: individuals: V4641 Sgr (1)
- X-rays: stars (1)
- astroparticle physic (1)
- black hole physics (1)
- catalogs (1)
- convection (1)
- cosmic background radiation (1)
- dark matter detectors (1)
- dark matter experiments (1)
- diffuse radiation (1)
- diffusion (1)
- dwarfs galaxies (1)
- galaxies: distances and redshifts (1)
- galaxies: individual: PKS 0625-354 (1)
- galaxies: magnetic fields (1)
- galaxies: nuclei (1)
- galaxies: starburst (1)
- gamma ray detectors (1)
- gamma rays: (1)
- gamma rays: general(HESS J0632+057, VER J0633+057) (1)
- gamma-ray burst: individual (GRB 170817A) (1)
- gamma-ray burst: individual: GRB 100621A (1)
- gamma-rays: ISM (1)
- gamma-rays: general (1)
- gravitational lensing: strong (1)
- gravitational waves (1)
- infrared: diffuse background (1)
- intergalactic medium (1)
- methods: observational (1)
- quasars: individual: 3C 279 (1)
- stars: black holes (1)
- stars: early-type (1)
- stars: individual: 1FGL J1018.6-5856 (1)
- stars: magnetars (1)
- stars: winds, outflows (1)
- supernovae: general (1)
- supernovae: individual: HESS J1818-154 (1)
Institute
Discovery of high and very high-energy emission from the BL Lacertae object SHBL J001355.9-185406
(2013)
The detection of the high-frequency peaked BL Lac object (HBL) SHBL J001355.9-185406 (z = 0.095) at high (HE; 100 MeV < E < 300 GeV) and very high-energy (VHE; E > 100 GeV) with the Fermi Large Area Telescope (LAT) and the High Energy Stereoscopic System (H.E.S.S.) is reported. Dedicated observations were performed with the H. E. S. S. telescopes, leading to a detection at the 5.5 sigma significance level. The measured flux above 310 GeV is (8.3 +/- 1.7(stat) +/- 1.7(sys)) x 10(-13) photons cm(-2) s(-1) (about 0.6% of that of the Crab Nebula), and the power-law spectrum has a photon index of Gamma = 3.4 +/- 0.5(stat) +/- 0.2(sys). Using 3.5 years of publicly available Fermi-LAT data, a faint counterpart has been detected in the LAT data at the 5.5 sigma significance level, with an integrated flux above 300 MeV of (9.3 +/- 3.4(stat) +/- 0.8(sys)) x 10(-10) photons cm(-2) s(-1) and a photon index of Gamma = 1.96 +/- 0.20(stat) +/- 0.08(sys). X-ray observations with Swift-XRT allow the synchrotron peak energy in vF(v) representation to be located at similar to 1.0 keV. The broadband spectral energy distribution is modelled with a one-zone synchrotron self-Compton (SSC) model and the optical data by a black-body emission describing the thermal emission of the host galaxy. The derived parameters are typical of HBLs detected at VHE, with a particle-dominated jet.
Discovery of very high energy gamma-ray emission from the BL Lacertae
object PKS0301-243 with HESS
(2013)
The active galactic nucleus PKS 0301-243 (z = 0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV < E < 100 GeV) by Fermi/LAT. This paper reports on the discovery of PKS 0301-243 at very high energies (E > 100 GeV) by the High Energy Stereoscopic System (H.E.S.S.) from observations between September 2009 and December 2011 for a total live time of 34.9 h. Gamma rays above 200 GeV are detected at a significance of 9.4 sigma. A hint of variability at the 2.5 sigma level is found. An integral flux I(E > 200GeV) = (3.3 +/- 1.1(stat) +/- 0.7(syst)) x 10(-12) ph cm(-2) s(-1) and a photon index Gamma = 4.6 +/- 0.7(stat) +/- 0.2(syst) are measured. Multi-wavelength light curves in HE, X-ray and optical bands show strong variability, and a minimal variability timescale of eight days is estimated from the optical light curve. A single-zone leptonic synchrotron self-Compton scenario satisfactorily reproduces the multi-wavelength data. In this model, the emitting region is out of equipartition and the jet is particle dominated. Because of its high redshift compared to other sources observed at TeV energies, the very high energy emission from PKS 0301-243 is attenuated by the extragalactic background light (EBL) and the measured spectrum is used to derive an upper limit on the opacity of the EBL.
A deep observation campaign carried out by the High Energy Stereoscopic System (HESS) on Centaurus A enabled the discovery of gamma-rays from the blazar 1ES 1312-423, 2 degrees away from the radio galaxy. With a differential flux at 1 TeV of phi(1 TeV) = (1.9 +/- 0.6(stat) +/- 0.4(sys)) x 10(-13) cm(-2) s(-1) TeV-1 corresponding to 0.5 per cent of the Crab nebula differential flux and a spectral index Gamma = 2.9 +/- 0.5(stat) +/- 0.2(sys), 1ES 1312-423 is one of the faintest sources ever detected in the very high energy (E > 100 GeV) extragalactic sky. A careful analysis using three and a half years of Fermi Large Area Telescope (Fermi-LAT) data allows the discovery at high energies (E > 100 MeV) of a hard spectrum (Gamma = 1.4 +/- 0.4(stat) +/- 0.2(sys)) source coincident with 1ES 1312-423. Radio, optical, UV and X-ray observations complete the spectral energy distribution of this blazar, now covering 16 decades in energy. The emission is successfully fitted with a synchrotron self-Compton model for the non-thermal component, combined with a blackbody spectrum for the optical emission from the host galaxy.
Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model of particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent magnetic fields, the existence of ALPs can modify the energy spectrum of the gamma rays for a sufficiently large coupling between ALPs and photons. This modification would take the form of an irregular behavior of the energy spectrum in a limited energy range. Data from the H. E. S. S. observations of the distant BL Lac object PKS 2155 - 304 (z = 0.116) are used to derive upper limits at the 95% C. L. on the strength of the ALP coupling to photons, g(gamma a) < 2.1 x 10(-11) GeV-1 for an ALP mass between 15 and 60 neV. The results depend on assumptions on the magnetic field around the source, which are chosen conservatively. The derived constraints apply to both light pseudoscalar and scalar bosons that couple to the electromagnetic field.