Conveners
Stellar sources (galactic and extragalactic) I: Binaries
- Olaf Reimer (Universität Innsbruck)
The gamma-ray binary is composed of the compact object (pulsar/black hole)
and high mass OB star, and is gamma-ray loud object. In this talk, I will focus on recent theoretical and observational studies for the gamma-ray binary hosting Be star.
For PSR B1259-63/LS 2883, the origin of flare-like GeV emission after the second disk passage is puzzling, and it may be interpreted as a...
The $\eta$ Carinae binary system hosts a massive stars featuring the highest known mass-loss rate. The two colliding winds dissipate mechanical energy in the shock, accelerating particles up to relativistic energies, and producing high-energy $\gamma$-rays. We analysed Fermi LAT data over two full orbital periods, comparing them with the predictions of particle acceleration in hydrodynamic...
We studied gamma-ray emission from Cyg X-3 and Cyg X-1 with the LAT. With the currently improved calibration and background determination, we studied spectra and variability of Cyg X-3 in its soft, intermediate and hard states and during bright flares. We measured detailed spectra for all of the states except for finding upper limits only in the hard state, in spite of strong radio emission...
Recently published results using seven years of Fermi-LAT data shed new light on the still puzzling source class of particle-accelerating colliding-wind binary (CWB) systems.
While the claimed association of the system $\gamma^2$ Velorum (WR 11) with a high-energy $\gamma$-ray source contrasts the exclusivity of $\eta$ Carinae as the hitherto only detected $\gamma$-ray emitter of that...
Gamma-ray binaries, whose spectral energy distribution peaks above 1 MeV, are rare objects thought to be composed of a pulsar in orbit around a massive star. How many gamma-ray binaries are there in the Galaxy ? What are the prospects for detecting them ? We have carried out mock gamma-ray surveys of synthetic populations of gamma-ray binaries to answer these questions.
The TAIGA experiment is aiming to address important tasks in ground-based gamma-ray astronomy at energies from a few TeV – to several PeV. TAIGA combines almost all the techniques for gamma-ray air shower detection. First, an array of the imaging air Cherenkov telescopes is planned (three telescopes located at the distance of 800m in 2019). Second, an array of the wide angle Cherenkov timing...
A new extended gamma-ray source (named as PS J1934.5+1845) was detected with a significance of ~13σ at a location of 1.83 degrees away from the radio location of the Galactic supernova remnant 3C 400.2 using about 9 years of Fermi-LAT data. The 68% containment radius of PS J1934.5+1845's extension was found to be 0.61 degrees and PS J1934.5+1845 is showing a power-law type spectrum with a...
We analyse 32 Galactic globular clusters ( GC ) using 8 years of Pass 8 Fermi-LAT data in the range 60 MeV - 300 GeV with the analysis down to lower energy being performed for the first time. We confirm prior detections and refine their spectral energy distributions ( SED ). Using a phenomenological approach, we investigate the possible emission mechanisms responsible for the observed...
Persistent gamma-ray emission dominates the radiative output of gamma-ray binaries, which are thought to be the evolutionary precursors to X-ray binaries. Often, this is attributed to particle acceleration in the shock from the winds of an optical companion and rapidly spinning pulsar or inverse Compton scattering of UV photons in the relativistic jet of an accreting compact object. We...
In colliding-wind binary (CWB) systems, the supersonic winds of two stars collide, forming a wind-collision region (WCR) delimited by two shocks. Such systems are expected to produce a nonthermal distribution of energetic particles via diffusive shock acceleration (DSA) at the collisionless shocks. Interacting with the environment, relativistic electrons and/or protons are in turn expected to...
We have re-examined the properties of gamma-ray emitting globular clusters with the data obtained by Fermi LAT in the past nine years. In particular, we have investigated the role of metallicity in determining the size of millisecond pulsar populations in globular cluster.
