Conveners
Galactic sources
- Patrick Slane (Harvard-Smithsonian Center for Astrophysics)
Galactic sources
- Elena Orlando (Stanford University)
Galactic sources
- Yves Gallant (LUPM, CNRS/IN2P3, U. de Montpellier)
Galactic sources
- Pablo Saz Parkinson (The University of Hong Kong)
Supernova remnants (SNRs) have been studied at GeV energies using the Fermi Large Area Telescope (LAT) for nearly a decade. The detection of the pion bump in four SNRs demonstrates that these are sources of cosmic ray protons. However, the detailed physics of particle acceleration (or re-acceleration) and diffusion remain undetermined. To determine the Galactic cosmic ray contribution from...
The Galactic Center region is one of the primary targets for
observations with the current generation of gamma-ray telescopes. This
attention is primarily caused by the presence of a black hole of 4
million solar masses, which provides a rare opportunity to study
the interaction of a super-massive black hole with surrounding matter
at a relatively close distance. Recently the interest to this...
An anomalous, apparently diffuse, gamma-ray signal not readily attributable to known Galactic sources has been found in Fermi space telescope data covering the central ~10 degrees of the Galaxy. This "Galactic Center Gamma-Ray Excess" (GCE) signal has a spectral peak at ~2 GeV and reaches its maximum intensity at the Galactic Centre (GC) from where it falls off as a radial power law...
Several groups have demonstrated the existence of an excess in the gamma-ray emission around the Galactic Center (GC) with respect to the predictions from a variety of Galactic Interstellar Emission Models (GIEMs) and point source catalogs. The origin of this excess, peaked at a few GeV, is still under debate. A possible interpretation is that it comes from a population of unresolved...
A clear excess at ~2 GeV, known as the Galactic-Center Excess (GCE), has been detected in the Galactic Bulge region by the Fermi telescope. In addition, the Galactic Bulge is characterised by the annihilation of positrons resulting in a 511 keV line. Both signals look morphologically similar, but so far a detailed comparison has been lacking from the literature. We model the GCE using the new...
Supernova remnants (SNRs) are the long lived structures that result from the explosive end of a massive star. The expanding shock-front produced by the supernova explosion heats stellar ejecta and swept-up ISM to X-ray emitting temperatures, and are sites in which populations of relativistic particles can be efficiently accelerated to the knee of the Cosmic-ray spectrum. For SNRs that are born...
The Vela supernova remnant is a canonical example of a middle-aged
composite system in which the SNR reverse shock has disrupted the
central pulsar wind nebula, Vela X. Due to a non-uniform ambient
medium, the shock has propagated asymmetrically, crushing the
northern part of the PWN. The result is a complex structure
characterized by nonthermal X-rays from the pulsar wind, thermal
X-rays from...
The survey of the Galactic plane in TeV gamma-rays by H.E.S.S.
allows a systematic study of the population of pulsar wind nebulae
(PWNe) in this energy domain. We find a mild trend of decreasing
TeV luminosity with age, or decreasing spin-down power, as well as
a trend of increasing size with age. Older TeV PWNe are generally
displaced from the pulsar position, with offsets larger than...
I present the results of large kinetic simulations of particle acceleration at non-relativistic collisionless shocks, which allow an ab-initio investigation of diffusive shock acceleration (DSA) at the blast waves of supernova remnants, the most prominent sources of Galactic cosmic rays (GCRs).
Ion acceleration efficiency and magnetic field amplification are obtained as a function of the...
I will discuss cosmic ray production at relativistic shocks. I will emphasize the differences expected for relativistic shocks compared to non-relativistic ones and examine possible applications such as relativistic supernovae and gamma ray bursts.
The X-ray emission from pulsar wind nebulae arises from particles accelerated at the shock that terminates the relativistic, strongly magnetized pulsar wind. However, conventional theories of particle acceleration break down at this shock, because the combination of low particle density and strong magnetic field places it outside the
domain of validity of MHD. We first discuss how particles...
MAGIC is a stereoscopic system of two imaging atmospheric Cherenkov
telescopes, located at the Roque de los Muchachos Observatory,
in La Palma (Spain) sensitive to gamma rays from few tens of GeV to tens of TeV. Pulsar physics is one of important topics in the MAGIC scientific program. In 2008, MAGIC for the first time detected VHE gamma-rays demission above 25 GeV from the Crab pulsar. Ever...
The Sun must shine brightly in GeV—TeV gamma rays and neutrinos. These particles are produced by the interactions of cosmic rays with solar matter and radiation. Additional fluxes may be caused by the annihilation of dark matter in the solar core, perhaps with the eventual particles produced outside of the Sun through the decay of metastable mediators. Importantly, a new generation of...
Only a handful of High Mass X-ray Binaries (HMXB) in our galaxy are known emitters of TeV gamma rays. The variable VHE emission from these sources are generally attributed to modulation by their orbital periods but the particle acceleration and gamma-ray production processes in these HMXBs are not well understood. In its 10 years of operation, VERITAS has observed 2 of these TeV emitting...
Supernovae (SNe) and their remnants are important cosmic ray sources. However, the origin of one major type of SNe, the Type Ia, is still not well understood. Two most popular hypotheses are the single-degenerate scenario, where one white dwarf (WD) accretes matter from its giant companion until the Chandrasekhar limit is reached, and the double-degenerate scenario, where two WDs merge and...
The High-Altitude Water Cherenkov (HAWC) TeV Gamma-Ray Observatory in Mexico is a wide-field-of-view telescope with a nearly 100 % duty cycle. It has been taking data with a complete detector configuration since spring 2015 and is particularly well suited to measure very energetic transient and extended gamma-ray emission in our Galaxy. In my presentation, I will give an overview of the most...
The HAWC (High Altitude Water Cherenkov) observatory recently published their second source catalog with 39 very high energy gamma-ray sources based on 507 days of exposure time. We studied thirteen HAWC sources without known counterparts with VERITAS and Fermi-LAT data. VERITAS, an array of four imaging atmospheric Cherenkov telescopes observing gamma rays with energies higher than 85 GeV,...
The 2HWC gamma-ray catalog was recently released using 17 months of data from the HAWC observatory, a TeV surveying instrument located in Mexico. A total of 39 sources were detected, of which ~40% are not near known TeV sources and over half do not have clear association with known astrophysical sources. Many are extended and encompass multiple known X-ray and gamma-ray sources. In an effort...
Gamma ray astronomy provides a powerful way to study particle acceleration and diffusion within high-energy astrophysical phenomena such as supernova remnants and pulsar wind nebulae. Constructing a coherent physical picture of these sources requires the ability to detect extended regions of gamma-ray emission, the ability to analyze small-scale spatial variation within these regions, and the...
The Cygnus region consists of multiple gamma-ray source types such as pulsar wind nebulae (PWN), supernova remnants, binary systems, and star clusters. Several gamma-ray instruments have observed gamma-ray sources in this region. For instance, Fermi-LAT found gamma-ray emission at GeV energies due to a Cocoon of freshly accelerated cosmic rays, which is co-located with a known PWN seen by...
Giant Molecular Clouds (GMC) are large reservoirs of gas and dust in the galaxy, which makes them ideal for the production of gamma-ray emission due to the interaction of cosmic rays with the ambient gas. This gamma-ray emission is part of the galactic diffuse gamma-ray emission, which is useful for tracing the propagation and distribution of cosmic rays throughout our Galaxy. The search of...
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a continuously operated, wide field-of-view (FOV) observatory sensitive to 100 GeV - 100 TeV gamma rays and cosmic rays. HAWC has been making observations since summer 2012 and officially commenced data-taking operations with the full detector in March 2015. With an FOV of 2 steradians, HAWC observes 2/3 of the sky in 24 hours. ...