HESS Logo Welcome

Welcome to the webpages of H.E.S.S., one of the leading observatories studying very high energy (VHE) gamma-ray astrophysics. To learn more about H.E.S.S. and the high energy universe, or to view pictures from the telescopes and the site in Namibia visit the About H.E.S.S. section.

Follow H.E.S.S. on Twitter for news regarding the H.E.S.S. instrument and its science

HESS Logo News

Detection of TeV emission from the interaction region between the supernova remnant G349.7+0.2 and a molecular cloud
December 12, 2014

G349.7+0.2 is a young Galactic supernova remnant (SNR) located at the distance of 11.5 kpc and observed across the entire electromagnetic spectrum from radio to high energy (HE; 0.1 GeV < E < 100 GeV) gamma-rays. Radio and infrared observations indicate that the remnant is interacting with a molecular cloud. In this paper, the detection of very high energy (VHE, E > 100 GeV) gamma-ray emission coincident with this SNR with the High Energy Stereoscopic System (H.E.S.S.) is reported. This makes it one of the farthest Galactic SNR ever detected in this domain. The paper can be found on the preprint server: arXiv:1412.2251.

Diffuse Galactic gamma-ray emission with H.E.S.S
December 3, 2014

After completion of the systematic survey of the inner Galaxy, the H.E.S.S. experiment is in a prime position to observe large-scale diffuse emission at TeV energies. Data of the H.E.S.S. Galactic Plane Survey are investigated in regions off known gamma-ray sources. For the first time large-scale gamma-ray emission along the Galactic Plane using imaging atmospheric Cherenkov telescopes has been observed. The paper can be found on the preprint server: arXiv:1411.7568.

Discovery of the VHE gamma-ray source HESS J1832-093 in the vicinity of SNR G22.7-0.2
November 30, 2014

The region around the supernova remnant (SNR) W41 contains several TeV sources and has prompted the H.E.S.S. Collaboration to perform deep observations of this field of view. This resulted in the discovery of the new very high energy (VHE) source HESS J1832-093, spatially coincident with a part of the radio shell of the neighboring remnant G22.7-0.2. Dedicated XMM-Newton observations led to the discovery of a new X-ray point source spatially coincident with the TeV excess. The paper can be found on the preprint server: arXiv:1411.0572.

Search for dark matter annihilation signatures in H.E.S.S. observations of Dwarf Spheroidal Galaxies
October 31, 2014

Dwarf spheroidal galaxies are characterized by a large mass-to-light ratio.They are amongst the most promising candidates for indirect dark matter searches. During the last years the H.E.S.S. telescopes observed five of these dwarf galaxies for more than 140 hours in total, searching for TeV gamma-ray emission from annihilation of dark matter particles. In the absence of a significant signal new constraints on the annihilation cross-section applicable to Weakly Interacting Massive Particles (WIMPs) are derived by combining the observations of the five dwarf galaxies. The paper can be found on the preprint server: arXiv:1410.2589.

Long-term monitoring of PKS 2155−304 with ATOM and H.E.S.S.: investigation of optical/gamma-ray correlations in different spectral states
September 20, 2014

The paper reports the analysis of all the available optical and very high-energy gamma-ray data for the BL Lac object PKS 2155−304, collected simultaneously with the ATOM and H.E.S.S. telescopes from 2007 until 2009. The study also includes X-ray (RXTE, Swift) and high-energy gamma-ray (Fermi-LAT) data. During the period analysed, the source was transitioning from its flaring to quiescent optical states. The paper can be found on the preprint server: arXiv:1409.0253.

Discovery of the hard spectrum VHE gamma-ray source HESS J1641-463
August 31, 2014

H.E.S.S. reports the discovery of a remarkably hard spectrum source, HESS J1641-463. HESS J1641-463 remained unnoticed by the usual analysis techniques due to confusion with the bright nearby source HESS J1640-465. It emerged at a significance level of 8.5 standard deviations after restricting the analysis to events with energies above 4 TeV. It shows a moderate flux level of 1.8% of the Crab Nebula flux above 1 TeV, and a hard spectrum with a photon index of Gamma = 2.07. The paper can be found on the preprint server: arXiv:1408.5280.

Probing the gamma-ray emission from HESS J1834-087 using H.E.S.S. and Fermi LAT observations
July 14, 2014

Previous observations with HESS have revealed the existence of an extended very-high-energy gamma-ray source, HESS J1834-087, coincident with the SNR W41. The origin of the gamma-ray emission has been further investigated with HESS and the Fermi-LAT. The TeV source can be modeled with a sum of two components: one point-like and one significantly extended. Two main scenarios are proposed to explain the emission: a pulsar wind nebula (PWN) or the interaction of SNR W41 with a molecular cloud. The paper can be found on the preprint server: arXiv:1407.0862.

First results from H.E.S.S. II announced: Detection of pulsed gamma-ray emission from Vela in the 30 GeV energy range
June 27, 2014

At the Amsterdam Astroparticle 2014 Conference, H.E.S.S. spokesperson Christian Stegmann presented first results obtained using the 28 m telescope CT5, including the detection of the Crab Nebula, of the AGNs PKS 2155-304 and PG 1553+113, and of the Galactic Center. These (known) VHE sources were observed as part of CT5 commissioning and serve to verify telescope performance. A major highlight is the detection of pulsed emission from the Vela pulsar, in the energy range around 30 GeV, the first detection of pulsed emission using a ground-based gamma-ray instrument in the southern hemisphere, demonstrating the capabilities of the new instrument. The 8-sigma detection of pulsed emission is obtained using an analysis chain optimized to provide lowest energy threshold, with a detection area of 10^4 m^2 at 20 GeV. The presentation is available here.

Search for TeV Gamma-ray Emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S
May 17, 2014

The long gamma-ray burst (GRB) 100621A, at the time the brightest X-ray transient ever detected by Swift-XRT in the 0.3--10 keV range, has been observed with the four H.E.S.S. 12 m telescopes, starting about 700 s after the satellite trigger. Due to its relatively small redshift of z∼0.5, the favourable position in the southern sky and the relatively short follow-up time of the H.E.S.S. observations, this GRB could be within the sensitivity reach of the H.E.S.S. instrument. However, the analysis of the H.E.S.S. data shows no indication of emission and yields an integral flux upper limit above ∼380 GeV of 4.2×10^−12/cm^2s, assuming a simple Band function extension model. The paper can be found on the preprint server: arXiv:1405.0488.

TeV gamma-ray observations of the young synchrotron-dominated SNRs G1.9+0.3 and G330.2+1.0
April 24, 2014

The non-thermal nature of the X-ray emission from the shell-type supernova remnants (SNRs) G1.9+0.3 and G330.2+1.0 is an indication of intense particle acceleration in the shock fronts of both objects. G1.9+0.3, recently established as the youngest known SNR in the Galaxy, also offers a unique opportunity to study the earliest stages of SNR evolution in the VHE domain. Observations with H.E.S.S. span the period 2004-2010. No significant gamma-ray signal from G1.9+0.3 or G330.2+1.0 is detected. The results are discussed in the framework of both leptonic and hadronic particle acceleration scenarios. The paper can be found on the preprint server: arXiv:1404.1613.

Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011
Feb. 22, 2014

About 40% of the observation time of H.E.S.S. is dedicated to studying active galactic nuclei (AGN), with the aim of increasing the sample of known extragalactic very-high-energy sources and constraining the physical processes at play in potential emitters. H.E.S.S. observations of AGN, spanning a period from April 2004 to December 2011, are investigated to constrain AGN gamma-ray fluxes. Only the 47 sources without significant excess detected at the position of the targets are presented. For 41 objects, the flux upper limits are the most constraining reported to date. The paper can be found on the preprint server: arXiv:1402.2332.

HESS J1640-465 - an exceptionally luminous TeV gamma-ray SNR
Jan. 21, 2014

The results of follow-up observations of the TeV gamma-ray source HESSJ 1640-465 are reported. The TeV emission is significantly extended and overlaps with the north-western part of the shell of the SNR G338.3-0.0. The new H.E.S.S. results, a re-analysis of archival XMM-Newton data, and multi-wavelength observations suggest that a significant part of the gamma-ray emission from HESS J1640-465 originates in the SNR shell. In a hadronic scenario, the product of total proton energy and mean target density could be as high as 4x10^52 erg cm^-3, for a distance of 10 kpc. The paper can be found on the preprint server: arXiv:1401.4388.

Search for Extended gamma-ray Emission around AGN with H.E.S.S. and Fermi-LAT
Jan. 15, 2014

Very-high-energy gamma-ray emission from blazars inevitably gives rise to electron-positron pair production through the interaction of these gamma-rays with the Extragalactic Background Light (EBL). Depending on the magnetic fields in the proximity of the source, the cascade initiated from pair production can result in either an isotropic halo around an initially beamed source or a magnetically broadened cascade flux. A search for such halos in H.E.S.S. and Fermi data resulted in upper limits on the extended emission around 1ES 1101-232, 1ES 0229+200 and PKS 2155-304, at a level of few percent of the Crab nebula flux. The paper can be found on the preprint server: arXiv:1401.2915.

bmfb logo