Search Publications
MeV Dark Matter: Has It Been Detected?
Silk, Joseph; Hooper, Dan; Paul, Jacques +2 more
We discuss the possibility that the recent detection of 511keV γ rays from the galactic bulge, as observed by INTEGRAL, is a consequence of low mass (1 100 MeV) particle dark matter annihilations. We discuss the type of halo profile favored by the observations as well as the size of the annihilation cross section needed to account for the signal. …
Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?
Enßlin, T. A.; Pfrommer, C.
We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce γ-rays for which we develop an analytic formalism to deduce their spectral distribution. Assuming the CRp-to-thermal energy density ratio XCRp and the CRp spectr…
The Host Galaxy of GRB 031203: Implications of Its Low Metallicity, Low Redshift, and Starburst Nature
Chen, Hsiao-Wen; Graham, James R.; Dressler, Alan +6 more
We present Keck/NIRSPEC near-IR images and Magellan/IMACS optical spectroscopy of the host galaxy of GRB 031203. The host is an actively star-forming galaxy at z=0.1055+/-0.0001. This is the lowest redshift GRB to date, aside from GRB 980425. From the hydrogen Balmer lines, we infer an extinction of AV=3.62+/-0.25 or a total reddening E…
Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror
Gilfanov, M. R.; Sunyaev, R. A.; Sazonov, S. Yu. +6 more
We report the association of the recently discovered hard X-ray source IGR J17475-2822 with the giant molecular cloud Sgr B2 in the Galactic Center region. The broad band (3-200 keV) spectrum of the source constructed from data of different observatories strongly supports the idea that the X-ray emission of Sgr B2 is Compton scattered and reproces…
Discovery of Hard Nonthermal Pulsed X-Ray Emission from the Anomalous X-Ray Pulsar 1E 1841-045
Kuiper, L.; Hermsen, W.; Mendez, M.
We report the discovery of nonthermal pulsed X-ray/soft gamma-ray emission up to ~150 keV from the anomalous 11.8 s X-ray pulsar AXP 1E 1841-045 located near the center of supernova remnant Kes 73 using Rossi X-Ray Timing Explorer (RXTE) Proportional Counter Array and High Energy X-Ray Timing Experiment (HEXTE) data. The morphology of the double-p…
The First IBIS/ISGRI Soft Gamma-Ray Galactic Plane Survey Catalog
Hill, A. B.; Walter, R.; Malaguti, G. +16 more
We report the first high-energy survey catalog obtained with the IBIS gamma-ray imager on board INTEGRAL. The analysis has been performed on the first-year Core Program ISGRI data comprising both Galactic Plane Scan and Galactic Centre Deep Exposure pointings for a total exposure time exceeding 5 Ms. This initial survey has revealed the presence o…
An apparently normal γ-ray burst with an unusually low luminosity
Sunyaev, R. A.; Sazonov, S. Yu.; Lutovinov, A. A.
Much of the progress in understanding γ-ray bursts (GRBs) has come from studies of distant events (redshift z ~ 1). In the brightest GRBs, the γ-rays are so highly collimated that the events can be seen across the Universe. It has long been suspected that the nearest and most common events have been missed because they are not as collimated or the…
A Hard X-ray Survey of the Galactic-Center Region with the IBIS Telescope of the INTEGRAL Observatory: A Catalog of Sources
Gilfanov, M. R.; Sunyaev, R. A.; Cherepashchuk, A. M. +6 more
From August 23 through September 24, 2003, the INTEGRAL Observatory conducted a deep survey of the Galactic-Center region with a record-breaking sensitivity at energies above 20 keV. We have analyzed the images of the Galactic-Center region obtained with the ISGRI detector of the IBIS telescope (15-200 keV) and give a catalog of detected sources. …
The Optical/Near-Infrared Counterpart of the INTEGRAL Obscured Source IGR J16318-4848: An sgB[e] in a High-Mass X-Ray Binary?
Filliatre, P.; Chaty, S.
The X-ray source IGR J16318-4848 was the first source discovered by INTEGRAL on 2003 January 29. The high-energy spectrum exhibits such a high column density that the source is undetectable in X-rays below 2 keV. On 2003 February 23-25, we triggered our Target of Opportunity (ToO) program using the EMMI and SOFI instruments on the New Technology T…
A Hard X-ray Survey of the Sagittarius Arm Tangent with the IBIS Telescope of the INTEGRAL Observatory: A Catalog of Sources
Sunyaev, R. A.; Postnov, K. A.; Cherepashchuk, A. M. +3 more
We analyze the images of the Sagittarius Arm tangent obtained with the IBIS telescope of the INTEGRAL observatory in the energy range 18-120 keV during its observations in the spring of 2003. We detected 28 sources at a statistically significant level with fluxes above 1.4 mCrab in the energy range 18-60 keV. Of these sources, 16 were previously i…