Search Publications
A theory of dark matter
Arkani-Hamed, Nima; Finkbeiner, Douglas P.; Slatyer, Tracy R. +1 more
We propose a comprehensive theory of dark matter that explains the recent proliferation of unexpected observations in high-energy astrophysics. Cosmic ray spectra from ATIC and PAMELA require a WIMP (weakly interacting massive particle). with mass Mχ∼500 800GeV that annihilates into leptons at a level well above that expected from a the…
Self-Consistent Models of the AGN and Black Hole Populations: Duty Cycles, Accretion Rates, and the Mean Radiative Efficiency
Miralda-Escudé, Jordi; Weinberg, David H.; Shankar, Francesco
We construct evolutionary models of the populations of active galactic nuclei (AGNs) and supermassive black holes, in which the black hole mass function grows at the rate implied by the observed luminosity function, given assumptions about the radiative efficiency and the luminosity in Eddington units. We draw on a variety of recent X-ray and opti…
The Space Density of Compton-Thick Active Galactic Nucleus and the X-Ray Background
Treister, E.; Urry, C. Megan; Virani, Shanil
We constrain the number density and evolution of Compton-thick (CT) active galactic nuclei (AGNs). In the local universe, we use the wide-area surveys from the Swift and INTEGRAL satellites, while for high redshifts we explore candidate selections based on a combination of X-ray and mid-infrared (mid-IR) parameters. We find a significantly lower s…
The evolution of the high-energy cut-off in the X-ray spectrum of GX 339-4 across a hard-to-soft transition
Belloni, T.; Homan, J.; Motta, S.
We report on X-ray observations of the black hole candidate GX 339-4 during its 2006/2007 outburst. The hardness-intensity diagram (HID) of all RXTE/Proportional Counter Array data combined shows a q-shaped track similar to that observed in previous outbursts. The evolution through the HID suggests that in the early phase of the outburst the sourc…
The second INTEGRAL AGN catalogue
Mas-Hesse, J. M.; Gehrels, N.; Ricci, C. +7 more
Aims: The INTEGRAL mission provides a large data set for studying the hard X-ray properties of AGN and allows testing of the unified scheme for AGN.
Methods: We present analysis of INTEGRAL IBIS/ISGRI, JEM-X, and OMC data for 199 AGN supposedly detected by INTEGRAL above 20 keV.
Results: The data analysed here allow significant spectral ex…
Variable Polarization Measured in the Prompt Emission of GRB 041219A Using IBIS on Board INTEGRAL
Götz, Diego; Laurent, Philippe; Lebrun, François +2 more
Polarization measurements provide a direct insight into the nature of astrophysical processes. Unfortunately, only a few instruments are available for this kind of measurement at γ-ray energies, and the sources need to be very bright. Gamma-ray bursts (GRBs) are ideal candidates due to their large flux over limited time intervals, maximizing the a…
The First Swift Ultraviolet/Optical Telescope GRB Afterglow Catalog
Cucchiara, A.; Brown, P. J.; Page, M. J. +21 more
We present the first Swift Ultraviolet/Optical Telescope (UVOT) gamma-ray burst (GRB) afterglow catalog. The catalog contains data from over 64,000 independent UVOT image observations of 229 GRBs first detected by Swift, the High Energy Transient Explorer 2 (HETE2), the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), and the Interplane…
The redshift and afterglow of the extremely energetic gamma-ray burst GRB 080916C
Cenko, S. B.; Greiner, J.; Berger, E. +22 more
Context: The detection of GeV photons from gamma-ray bursts (GRBs) has important consequences for the interpretation and modelling of these most-energetic cosmological explosions. The full exploitation of the high-energy measurements relies, however, on accurate knowledge of the distance to the events.
Aims: Here we report on the discovery of …
Simultaneous Multi-Wavelength Observations of Sgr A* During 2007 April 1-11
Grosso, N.; Dowell, C. D.; Porquet, D. +18 more
We report the detection of variable emission from Sgr A* in almost all wavelength bands (i.e., centimeter, millimeter, submillimeter, near-IR, and X-rays) during a multi-wavelength observing campaign. Three new moderate flares are detected simultaneously in both near-IR and X-ray bands. The ratio of X-ray to near-IR flux in the flares is consisten…
Detection of Gamma-Ray Emission from the Eta-Carinae Region
Antonelli, L. A.; Pian, E.; Costa, E. +63 more
We present the results of extensive observations by the gamma-ray AGILE satellite of the Galactic region hosting the Carina nebula and the remarkable colliding wind binary Eta Carinae (η Car) during the period 2007 July-2009 January. We detect a gamma-ray source (1AGL J1043-5931) consistent with the position of η Car. If 1AGL J1043-5931 is associa…