A5079992732- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Neutrino Physics Research
- Particle Accelerators and Free-Electron Lasers
- Dark Matter and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Computational Physics and Python Applications
- Particle Detector Development and Performance
- Particle accelerators and beam dynamics
- Particle physics theoretical and experimental studies
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- X-ray Spectroscopy and Fluorescence Analysis
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Astrophysics and Star Formation Studies
- Superconducting Materials and Applications
- Advanced X-ray Imaging Techniques
- Photocathodes and Microchannel Plates
European Southern Observatory
2015-2024
Office National d'Études et de Recherches Aérospatiales
2024
Osservatorio di Astrofisica e Scienza dello Spazio
2021-2023
National Institute for Astrophysics
2014-2023
Technical University of Munich
2019-2021
Institute for Advanced Study
2021
Astronomical Observatory of Rome
2013-2020
Kyoto University
2019
Pennsylvania State University
2019
Joint Institute for VLBI ERIC
2007-2019
The appearance of active galactic nuclei (AGN) depends so strongly on orientation that our current classification schemes are dominated by random pointing directions instead more interesting physical properties. Light from the centers many AGN is obscrued optically thick circumstellar matter, particularly at optical and ultraviolet wavelengths. In radio-loud AGN, bipolar jets emanating nucleus emit radio through gamma-ray light relativistically beamed along jet axes. Understanding origin...
This special issue of the Astrophysical Journal Letters is dedicated to presenting initial results from Great Observatories Origins Deep Survey (GOODS) that are primarily, but not exclusively, based on multiband imaging data obtained with Hubble Space Telescope and Advanced Camera for Surveys (ACS). The survey covers roughly 320 arcmin2 in ACS F435W, F606W, F814W, F850LP bands, divided into two well-studied fields. Existing deep observations Chandra X-Ray Observatory ground-based facilities...
view Abstract Citations (620) References (67) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Connection between X-Ray-- and Radio-selected BL Lacertae Objects Padovani, Paolo ; Giommi, We explain the properties of X-ray-selected objects, under assumption that they constitute small minority Lac population with energy cutoff located in UV/X-ray band as suggested by their multifrequency spectra. In particular, we derive X-ray luminosity function, log N-log...
view Abstract Citations (540) References (120) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Relativistic Bulk Motion in Active Galactic Nuclei Ghisellini, G. ; Padovani, P. Celotti, A. Maraschi, L. We discuss the evidence for relativistic bulk motion of emitting plasma nuclei ~100 radio sources, which include BL Lacertae objects, quasars, and galaxies, with published VBLI measurements core angular dimension flux. Comparing predicted observed high-frequency...
view Abstract Citations (519) References (77) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Complete Sample of 1 Jansky BL Lacertae Objects. I. Summary Properties Stickel, M. ; Padovani, P. Urry, C. Fried, J. W. Kuehr, H. This paper describes the first homogeneous, flux-limited sample radio-selected Lac objects, taken from Jy survey Kuhr et al. These 34 objects comprise only well-defined outside X-ray band. selection criteria include flat radio spectra,...
EMU is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The primary goal of to make deep (rms ~ 10 microJy/beam) entire Southern Sky at 1.3 GHz, extending as far North +30 degrees declination, with resolution arcsec. expected detect and catalogue about 70 million galaxies, including typical star-forming galaxies up z~1, powerful starbursts even greater redshifts, AGNs edge visible Universe. It will undoubtedly discover...
We propose a scenario where blazars are classified as flat-spectrum radio quasars (FSRQs), BL Lacs, low synchrotron, or high synchrotron peaked objects according to varying mix of the Doppler boosted radiation from jet, emission accretion disk, broad line region, and light host galaxy. In this framework peak energy power (nu_peak) in is independent source type luminosity. test new approach, which builds upon unified schemes, using extensive Monte Carlo simulations show that it can provide...
We present evidence in favour of a link between the luminosity radiatively dissipated central engine radio-loud Active Galactic Nuclei and kinetic power their jets. This piece is based on relation we find broad emission lines pc-scale radio jets, for sample quasars which suitable data are available literature. that ionizing one same order magnitude, suggesting processes responsible them somehow related. A strong magnetic field equipartition with radiation could be regulating both processes....
view Abstract Citations (193) References (69) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Stellar Mass Loss in Elliptical Galaxies and the Fueling of Active Galactic Nuclei Padovani, Paolo ; Matteucci, Francesca The connection between some observational properties active galactic nuclei their host galaxies is studied using a self-consistent model evolution which reproduces main features elliptical galaxies. It shown that stellar mass loss, calculated...
We have undertaken a survey, the Deep X-Ray Radio Blazar Survey (DXRBS), of archived, pointed ROSAT Position Sensitive Proportional Counter data for blazars by correlating WGACAT database with several publicly available radio catalogs, restricting our candidate list to serendipitous flat spectrum sources (αr ≤ 0.70, where Sν ∝ ν). discuss survey methods, identification procedure, and first results. Our is found be ∼95% efficient at finding flat-spectrum radio-loud quasars (FSRQs; 59 85...
The recent IceCube discovery of 0.1–1 PeV neutrinos astrophysical origin opens up a new era for high-energy astrophysics. Although there are various candidate sources, firm association the detected with one (or more) them is still lacking. A analysis plausible counterparts within error circles events showed that likely nine include mostly BL Lacs, among which Mrk 421. Motivated by this result and previous independent on neutrino emission from 421, we test Lac–neutrino connection in context...
We present the dissection in space, time, and energy of region around IceCube-170922A neutrino alert. This study is motivated by: (1) first association between a alert blazar flaring state, TXS 0506+056; (2) evidence activity during 2014 - 2015 from same direction; (3) lack an accompanying simultaneous $\gamma$-ray enhancement counterpart; (4) contrasting neighbouring bright source, PKS 0502+049, 2015. Our makes use multi-wavelength archival data accessed through Open Universe tools includes...
The sub-mJy radio population is a mixture of active systems, that star forming galaxies (SFGs) and galactic nuclei (AGNs). We study sample 883 sources detected at 1.4 GHz in deep Very Large Array survey the Extended Chandra Deep Field South (E-CDFS) reaches best rms sensitivity 6 microJy. have used simple scheme to disentangle SFGs, radio-quiet (RQ), radio-loud (RL) AGNs based on combination data with X-ray mid-infrared observations from Spitzer. find flux densities between about 30 100...
We present evidence that TXS 0506+056, the first plausible non-stellar neutrino source, despite appearances, is not a blazar of BL Lac type but instead masquerading Lac, i.e., intrinsically flat-spectrum radio quasar with hidden broad lines and standard accretion disk. This re-classification based on: (1) its O II luminosities; (2) emission line ratios; (3) Eddington ratio. also point out synchrotron peak frequency 0506+056 more than two orders magnitude larger expected by so-called "blazar...
We explore the correlation of $\gamma$-ray emitting blazars with IceCube neutrinos by using three very recently completed, and independently built, catalogues latest neutrino lists. introduce a new observable, namely number events at least one counterpart, $N_{\nu}$. In all we consistently observe positive fluctuation $N_{\nu}$ respect to mean random expectation significance level $0.4 - 1.3$ per cent. This applies only extreme blazars, strong, high energy sources peaked type, implies...
We present the evolutionary properties and luminosity functions of radio sources belonging to Chandra Deep Field South VLA survey, which reaches a flux density limit at 1.4 GHz 43 microJy field center redshift ~5, includes first radio-selected complete sample radio-quiet active galactic nuclei (AGN). use new, comprehensive classification scheme based on radio, far- near-IR, optical, X-ray data disentangle star-forming galaxies from AGN radio-loud AGN. confirm our previous result that become...
IceCube has recently reported the discovery of high-energy neutrinos astrophysical origin, opening up PeV (10^15 eV) sky. Because their large positional uncertainties, these events have not yet been associated to any source. We found plausible astronomical counterparts in GeV -- TeV bands by looking for sources available area gamma-ray catalogues within error circles events. then built spectral energy distribution and compared it with flux corresponding neutrino. Likely include mostly BL...
Deep radio observations at 1.4GHz for the Extended Chandra Field South were performed in June through September of 2007 and presented a first data release (Miller et al. 2008). The survey was made using six separate pointings Very Large Array (VLA) with over 40 hours observation per pointing. In current paper, we improve on reduction to produce second (DR2) mosaic image. This DR2 image covers an area about third square degree reaches best rms sensitivity 6 uJy has typical 7.4 2.8" by 1.6"...
We study the Extended Chandra Deep Field South (E-CDFS) Very Large Array sample, which reaches a flux density limit at 1.4 GHz of 32.5 microJy field centre and redshift ~ 4, covers 0.3 deg^2. Number counts are presented for whole sample while evolutionary properties luminosity functions derived active galactic nuclei (AGN). The faint radio sky contains two totally distinct AGN populations, characterised by very different evolutions, functions, Eddington ratios: radio-quiet...
Blazars have been suggested as possible neutrino sources long before the recent IceCube discovery of high-energy neutrinos. We re-examine this possibility within a new framework built upon blazar simplified view and self-consistent modelling emission from individual sources. The former is recently proposed paradigm that explains diverse statistical properties blazars adopting minimal assumptions on blazars' physical geometrical properties. This view, tested through detailed Monte Carlo...