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Start Over Author "Palumbo, Giorgio G. C." Topic astrophysics
5 results on '"Palumbo, Giorgio G. C."'

1. Broad Line Radio Galaxies: Jet Contribution to the nuclear X-Ray Continuum

Author

Grandi, Paola and Palumbo, Giorgio G. C.

Subjects
Astrophysics
Abstract

It is shown that, for Broad Line Radio Galaxies the strength of the non-thermal beamed radiation, when present, is always smaller than the accretion flow by a factor < 0.7 in the 2-10 keV band. The result has been obtained using the procedure adopted for disentangling the Flat Spectrum Radio Quasar 3C 273 (Grandi & Palumbo 2004). Although this implies a significantly smaller non-thermal flux in Radio Galaxies when compared to Blazars, the jet component, if present, could be important at very high energies and thus easily detectable with GLAST., Comment: 12 pages including 2 figures (4 files), ApJ accepted

Published
2006
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2. Extreme Synchrotron Blazars in Outburst: the Potentiality of INTEGRAL Imaging and Spectroscopy

Author

Pian, Elena, Malaguti, Giuseppe, Maraschi, Laura, Ghisellini, Gabriele, and Palumbo, Giorgio G. C.

Subjects
Astrophysics
Abstract

Only ~10 blazars have been detected in soft gamma-rays by OSSE and the PDS, often in flaring state. We investigate the impact of the imaging and spectral capabilities of the IBIS instrument on board INTEGRAL on the study of blazars. The objectives are: 1) to remove ambiguities in the identification of some blazars as soft gamma-ray emitters; 2) to determine the spectral shape of "extreme synchrotron" blazars, namely sources with high F_X/F_radio ratios, for which the synchrotron component peaks at far UV-soft X-ray frequencies. We expect that in these sources the synchrotron peak shifts to higher energies during outbursts, making them strong soft gamma-ray emitters, and therefore possible targets for INTEGRAL wide band X- and gamma-ray spectroscopy., Comment: 4 pages, Latex, 2 PostScript figures, to appear in the Proceedings of the 3rd INTEGRAL Workshop "The Extreme Universe", held in Taormina, Italy, 14-18 September 1998

Published
1998

3. JETS AND OUTFLOWS IN RADIO GALAXIES: IMPLICATIONS FOR AGN FEEDBACK

Author

Paola Grandi, Elena Torresi, Elisa Costantini, Giorgio G. C. Palumbo, Torresi, Eleonora, Grandi, Paola, Costantini, Elisa, and Palumbo, GIORGIO G. C.

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, astro-ph.HE, Jet (fluid), Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, Galaxy formation and evolution, Astrophysics - High Energy Astrophysical Phenomena, Galaxy cluster, Astrophysics::Galaxy Astrophysics, Line (formation)
Abstract

One of the main debated astrophysical problems is the role of the AGN feedback in galaxy formation. It is known that massive black holes have a profound effect on the formation and evolution of galaxies, but how black holes and galaxies communicate is still an unsolved problem. For Radio Galaxies, feedback studies have mainly focused on jet/cavity systems in the most massive and X-ray luminous galaxy clusters. The recent high-resolution detection of warm absorbers in some Broad Line Radio Galaxies allow us to investigate the interplay between the nuclear engine and the surrounding medium from a different perspective. We report on the detection of warm absorbers in two Broad Line Radio Galaxies, 3C 382 and 3C 390.3, and discuss the physical and energetic properties of the absorbing gas. Finally, we attempt a comparison between radio-loud and radio-quiet outflows., To be published in the proceedings of High Energy Phenomena in Relativistic Outflows III (HEPRO III, IJMPCS). 4 pages, 2 figures

Published
2012

4. Radio Lobes of Pictor A: an X-ray spatially resolved Study

Author

Carlo Stanghellini, Gianfranco Brunetti, Giulia Migliori, Paola Grandi, Giorgio G. C. Palumbo, Migliori Giulia, Grandi Paola, Palumbo Giorgio G. C., Brunetti Gianfranco, and Stanghellini Carlo

Subjects
Physics, Photon, Uniform distribution (continuous), Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Cosmic microwave background, Astrophysics (astro-ph), Compton scattering, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Electron, Astrophysics::Cosmology and Extragalactic Astrophysics, Magnetic field, Space and Planetary Science, Equipartition theorem, Astrophysics::Galaxy Astrophysics
Abstract

A new XMM observation has made possible a detailed study of both lobes of the radio galaxy Pictor A. Their X-ray emission is of non thermal origin and due to Inverse Compton scattering of the microwave background photons by relativistic electrons in the lobes, as previously found. In both lobes, the equipartition magnetic field (Beq) is bigger than the Inverse Compton value (Bic), calculated from the radio and X-ray flux ratio. The Beq/Bic ratio never gets below 2, in spite of the large number of reasonable assumptions tested to calculate Beq, suggesting a lobe energetic dominated by particles. The X-ray data quality is good enough to allow a spatially resolved analysis. Our study shows that Bic varies through the lobes. It appears to increase behind the hot spots. On the contrary, a rather uniform distribution of the particles is observed. As a consequence, the radio flux density variation along the lobes appears to be mainly driven by magnetic field changes., 15 pages, 3 figures, ApJ accepted

Published
2007

5. Broad-Line Radio Galaxies: Jet Contribution to the Nuclear X-Ray Continuum

Author

Giorgio G. C. Palumbo, Paola Grandi, Grandi Paola, and Palumbo Giorgio G. C.

Subjects
Physics, Active galactic nucleus, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Radiation, Accretion (astrophysics), X-shaped radio galaxy, Space and Planetary Science, Basso continuo, Blazar, Astrophysics::Galaxy Astrophysics
Abstract

It is shown that for broad-line radio galaxies the strength of the nonthermal beamed radiation, when present, is always smaller than the accretion flow by a factor of

Published
2007

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