Search Publications
Discovery of the binary pulsar PSR B1259-63 in very-high-energy gamma rays around periastron with HESS
Raux, J.; Ripken, J.; Funk, S. +99 more
We report the discovery of very-high-energy (VHE) γ-ray emission of the binary system
The all-sky distribution of 511 keV electron-positron annihilation emission
Knödlseder, J.; Schanne, S.; Schönfelder, V. +11 more
We present a map of 511 keV electron-positron annihilation emission, based on data accumulated with the SPI spectrometer aboard ESA's INTEGRAL gamma-ray observatory, that covers approximately ~95% of the celestial sphere. Within the exposed sky area, 511 keV line emission is significantly detected towards the galactic bulge region and, at a very l…
Gamma-Ray Constraint on Galactic Positron Production by MeV Dark Matter
Bertone, Gianfranco; Beacom, John F.; Bell, Nicole F.
The Galactic positrons, as observed by their annihilation gamma-ray line at 0.511 MeV, are difficult to account for with astrophysical sources. It has been proposed that they are produced instead by dark matter annihilation or decay in the inner Galactic halo. To avoid other constraints, these processes are required to occur “invisibly,” such that…
INTEGRAL observations of recurrent fast X-ray transient sources
Hill, A. B.; Bird, A. J.; Ubertini, P. +9 more
Fast X-ray Transients (FXTs) are believed to be non-recurrent bright X-ray sources lasting less than a day and occuring at serendipitous positions, they can best be detected and discovered by instruments having a sufficiently wide field of view and high sensitivity. The IBIS/ISGRI instrument onboard INTEGRAL is particularly suited to detect new or…
Positron annihilation spectrum from the Galactic Centre region observed by SPI/INTEGRAL
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +2 more
The electron-positron annihilation spectrum observed by SPI/INTEGRAL during deep Galactic Centre region exposure is reported. The line energy (510.954+/-0.075 keV) is consistent with the unshifted annihilation line. The width of the annihilation line is 2.37 +/- 0.25 keV (full width at half-maximum), while the strength of the ortho-positronium con…
High-Energy Gamma Rays from the Massive Black Hole in the Galactic Center
Aharonian, F.; Neronov, A.
Accreting black holes (BHs) are believed to be sites of possible particle acceleration with conditions that are also favorable for effective gamma-ray production. However, because of photon-photon pair production, only low-energy (MeV) gamma rays can escape these compact objects with typically very large compactness parameters, κ=(L/LEdd
INTEGRAL insight into the inner parts of the Galaxy. High mass X-ray binaries
Sunyaev, R.; Revnivtsev, M.; Lutovinov, A. +3 more
Since its launch INTEGRAL has devoted a significant fraction of its observing time to the Galactic plane region. We present the results of INTEGRAL observations of the inner spiral arms of the Galaxy (Norma, Scutum and Sagittarius) with attention to high mass X-ray binaries. The increased sensitivity of the survey and possibility to detect absorbe…
Gamma-ray continuum emission from the inner Galactic region as observed with INTEGRAL/SPI
Strong, A. W.; Bouchet, L.; Terrier, R. +5 more
The diffuse continuum emission from the Galactic plane in the energy range 18-1000 keV has been studied using 16 Ms of data from the SPI instrument on INTEGRAL. With such an exposure we can exploit the imaging properties of SPI to achieve a good separation of point sources from the various diffuse components. Using a candidate-source catalogue der…
Discovery of the Accretion-powered Millisecond X-Ray Pulsar IGR J00291+5934
Chakrabarty, Deepto; Galloway, Duncan K.; Markwardt, Craig B. +2 more
We report on observations of the sixth accretion-powered millisecond pulsar, IGR J00291+5934, with the Rossi X-Ray Timing Explorer. The source is a faint recurrent X-ray transient initially identified by the International Gamma-Ray Astrophysics Laboratory. The 599 Hz (1.67 ms) pulsation had a fractional rms amplitude of 8% in the 2-20 keV range, a…
Unstable relics as a source of galactic positrons
Pospelov, Maxim; Picciotto, Charles
We calculate the fluxes of 511 keV photons from the galactic bulge caused by positrons produced in the decays of relic particles with masses less than 100 MeV. In particular, we tighten the constraints on sterile neutrinos over a large domain of the mass-mixing angle parameter space, where the resulting photon flux would significantly exceed the e…