69 citations · 369 across the 14 of their papers we have counts for
10 papers · 1 filter
Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-Energy Emission from Prompt to Afterglow
M. Ajello, M. Arimoto, M. Axelsson +147
We report on the observations of gamma-ray burst (GRB) 190114C by the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory. The early-time observations reveal mul…
Breaking the spectral degeneracies in black hole binaries with fast timing data
M. Axelsson, C. Done
The spectra of black hole binaries in the low/hard state are complex, with evidence for multiple different Comptonisation regions contributing to the hard X-rays in addition to a c…
Temperature Structure in the Perseus Cluster Core Observed with Hitomi
Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu +192
The present paper investigates the temperature structure of the X-ray emitting plasma in the core of the Perseus cluster using the 1.8--20.0 keV data obtained with the Soft X-ray S…
Revealing the nature of the QPO and its harmonic in GX 339-4 using frequency-resolved spectroscopy
M. Axelsson, C. Done
We use frequency-resolved spectroscopy to examine the energy spectra of the prominent low frequency QPO and its harmonic in GX 339-4. We track the evolution of these spectra as the…
Extremely narrow spectrum of GRB110920A: further evidence for localised, subphotospheric dissipation
S. Iyyani, F. Ryde, B. Ahlgren +6
Much evidence points towards that the photosphere in the relativistic outflow in GRBs plays an important role in shaping the observed MeV spectrum. However, it is unclear whether t…
Varying Faces of Photospheric Emission in Gamma-Ray Bursts
M. Axelsson
Among the more than 1000 gamma-ray bursts observed by the Fermi Gamma-ray Space Telescope, a large fraction show narrow and hard spectra inconsistent with non-thermal emission, sig…
Fast variability as a probe of the smallest regions around accreting black holes
M. Axelsson, L. Hjalmarsdotter, C. Done
We extract the spectra of the fastest variability (above 10 Hz) from the black hole XTE J1550-564 during a transition from hard to soft state on the rise to outburst. We confirm pr…
APEX sub-mm monitoring of gamma-ray blazars
S. Larsson, L. Fuhrmann, A. Weiss +13
So far, no systematic long-term blazar monitoring programs and detailed variability studies exist at sub-mm wavelengths. Here, we present a new sub-mm blazar monitoring program usi…
Subphotospheric heating in GRBs: analysis and modeling of GRB090902B as observed by Fermi
T. Nymark, M. Axelsson, C. Lundman +3
We analyze the spectral evolution of GRB 090902B and show that subphotospheric dissipation can explain both the spectra and the spectral evolution. The emission from a GRB photosph…
Fermi Observations of the Very Hard Gamma-ray Blazar PG 1553+113
LAT Collaboration
We report the observations of PG 1553+113 during the first ~200 days of Fermi Gamma-ray Space Telescope science operations, from 4 August 2008 to 22 February 2009 (MJD 54682.7-5488…