Conveners
17 - Activity at the galactic center
- Denys Malyshev (University of Geneva)
17 - Activity at the galactic center
- Denys Malyshev (University of Geneva)
Mr
Ian Christie
(Purdue University)
17/12/2015, 14:00
Talk
A recent method has been proposed for probing the properties of the accretion disk surrounding Sgr A* located at our galactic center. This is based on a study of the collision between the disk fluid and the wind of the star, S2. We expand upon the previous work by constructing a semi-analytical model for the shock formation in the stellar wind. This takes into account the thermal pressure of...
Mr
Michael Walls
(DCU)
17/12/2015, 14:21
Talk
In the centre of our Galaxy lies a super-massive black hole, identified with the radio source Sagittarius A*. Sagittarius A* is quite dim in terms of total radiated energy, having a luminosity that is a factor of lower than its Eddington luminosity. However, there is compelling evidence that this source was far brighter in the past. This conclusion was derived from the detection of reflected...
Elena Orlando
(Stanford University)
17/12/2015, 14:42
Talk
Diffuse emission has dramatically increased the interest of the astrophysical community, due to recent detailed observations by Planck, Fermi-LAT, H.E.S.S. and VERITAS. Unfortunately disentangling and characterizing this diffuse emission strongly depends on uncertainties in the knowledge of unresolved sources, cosmic rays, matter, radiation fields, and magnetic fields.
We discuss here the...
Denys Malyshev
(University of Geneva)
17/12/2015, 15:24
Talk
The Galactic centre (GC) is a bright gamma-ray source with the GeV-TeV band spectrum composed of two distinct components in the 1-10 GeV and 1-10 TeV energy ranges. The nature of these two components is not clearly understood. We present imaging, spectral, and timing analysis of data from ~7 years of observations of the Galactic centre by FERMI/LAT gamma-ray telescope complemented by sub-MeV...
Dmitriy Chernyshov
(Lebedev's Institute of Physics, Moscow, Russia)
17/12/2015, 16:15
Talk
Fermi bubbles are giant gamma-ray structures seen above and below the Galactic plane with characteristic size of order of 10 kpc. They also show very good correlation with the microwave emission discovered by the WMAP telescope and the residual diffuse emission in the range above 30 GHz found by the Planck satellite. Correlation between gamma-ray emission observed by Fermi and radio emission...
Prof.
Bence Kocsis
(Eötvös University)
17/12/2015, 16:35
Talk
The Fermi satellite has recently detected gamma ray emission from the central regions of our Galaxy. This may be evidence for dark matter particles, a major component of the standard cosmological model, annihilating to produce high-energy photons. We show that the observed signal may instead be generated by millisecond pulsars that formed in dense star clusters in the Galactic halo. Most of...
Dr
Frederic Vincent
(Observatoire de Paris)
17/12/2015, 16:55
Talk
Near-future sub-millimetric VLBI observations of the surroundings of the Galactic center supermassive black hole, Sgr A*, by the Event Horizon Telescope (EHT) will lead to unprecedented constraints on the nature of the accretion flow surrounding this compact object. One of the most fascinating goal of the EHT is to test the presence of an event horizon by imaging the *black hole shadow*, and...
Prof.
Benjamin Brown
(Marquette University)
17/12/2015, 17:35
Talk
Positron annihilation at 511 keV coming from the direction of the Galactic Center could be occurring in a variety of different ways. One channel, in-flignt annihilation, occurs by charge exchange approximately below 100 eV as positrons slow by inelastic collisions from keV energies. The characteristic Doppler broadened line width and shape is of interest in comparing to galactic gamma ray data...
