相关论文: The role of microquasars in astroparticle physics
Thanks to aggressive campaigns of multi-wavelength observations of X-ray binaries in outbursts over the last decade or so, we have now reached a reasonable understanding of their radio phenomenology in response to changes in the global…
Quasars with flat radio spectra and one-sided, arc-second scale, ~100 mJy GHz radio jets are found to have similar scale X-ray jets in about 60% of such objects, even in short 5 to 10 ks Chandra observations. Jets emit in the GHz band via…
The field of high energy particle astronomy is exciting and rapidly developing. In the last few years, we have detected extragalactic sources of intense TeV gamma radiation and individual cosmic ray particles with energies exceeding 25…
Recent results, the present status and the perspectives of high energy gamma-ray astronomy are described. Since the satellite observations by the Compton Gamma Ray Observatory and its precursor missions have been reviewed extensively,…
Relativistic outflows are common in accreting and forming black holes. Despite the enormous differences in scale, stellar-mass black holes in X-ray binaries and supermassive black holes in Galactic Nuclei produce jets with analogous…
We present the first detailed low frequency radio measurements of the galactic microquasar GRS1915+105 with GMRT. Simultaneous observations were carried out at 610 and 244 MHz. Our data does not show any signature of spectral turn over even…
In these three lectures I discuss the present status of high-energy astroparticle physics including Ultra-High-Energy Cosmic Rays (UHECR), high-energy gamma rays, and neutrinos. The first lecture is devoted to ultra-high-energy cosmic rays.…
With their jet pointing towards us, blazars are ideal tools to study the physics and structure of extragalactic jets. Their powerful jets are cosmic particle accelerators and are alleged to be one of the production sites of the high-energy…
A solid theoretical understanding of how inflowing, accreting plasma around black holes and other compact objects gives rise to outflowing winds and jets is still lacking, despite decades of observations. The fact that similar processes and…
The jets of microquasars with high-mass stellar companions are exposed to the dense matter field of the stellar wind. We present estimates of the gamma-ray emission expected from the jet-wind hadronic interaction and we discuss the…
Recent measurements of ultra-high energy cosmic rays and neutrinos are briefly reviewed. With several new large scale observatories nearing completion or becoming fully operational only very recently, a large body of high quality and high…
SS433 is a Galactic microquasar with powerful jets, where very-high-energy particles are produced. We study particle acceleration in the jets of SS433 in the light of the recent multi-wavelength data from radio to TeV gamma ray. We first…
In this work, I present a qualitative discussion on the prospect of production of ultra-high photons in blazars. The sources are a subclass of active galactic nuclei which host supermassive black holes and fire relativistic jets into the…
This study focuses on high-redshift, z > 3, quasars where resolved X-ray jets remain underexplored in comparison to nearby sources. Building upon previous work, we identify and confirm extended kpc-scale jets emission in two quasars…
Ultra-high energy cosmic rays (UHECRs) are particles, likely protons and/or nuclei, with energies up to $10^{20}$ eV that are observed through the giant air showers they produce in the atmosphere. These particles carry the information on…
We report initial results from the detection of optical emission in the arcsecond-scale radio jets of two quasars utilizing images from the {\it Hubble Space Telescope} archive. The optical emission has a very knotty appearance and is…
We present a scenario for the variability of the microquasar GRS 1915+105. This starts from previous works, leading to the tentative identification of the Accretion-Ejection Instability as the source of the low-frequency Quasi-Periodic…
The interaction of microquasar jets with their environment can produce non-thermal radiation as is the case for extragalactic outflows impacting on their surroundings. We have developed an analytical model based on those successfully…
We analyse the radiation pressure instability of the standard, optically thisc disc and propose it as an explanation of the obseved variability of the superluminal microquasar GRS 1915+105. The quantitave agreement with the observed…
The recent discovery, by the Chandra satellite, that jets of blazars are strong X-ray emitters at large scales (0.1-1 Mpc) bears support to the hypothesis that (also) on these scales the emitting plasma is moving at highly relativistic…