A5050100365- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Particle physics theoretical and experimental studies
- Astronomical Observations and Instrumentation
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Particle Accelerators and Free-Electron Lasers
- Wildlife Ecology and Conservation
- Cosmology and Gravitation Theories
- Particle Detector Development and Performance
- Neutrino Physics Research
- Scientific Research and Discoveries
- Animal Ecology and Behavior Studies
- Dark Matter and Cosmic Phenomena
- Mechanics and Biomechanics Studies
- Adaptive optics and wavefront sensing
- Animal Behavior and Welfare Studies
- Nuclear physics research studies
- Evolution and Paleontology Studies
- Advanced X-ray Imaging Techniques
Istituto di Radioastronomia di Bologna
2020-2025
University of Southampton
2015-2024
Universidad Complutense de Madrid
2023
University of Manchester
2023
University College Cork
2023
Centro Científico Tecnológico Patagónico
2017-2022
University of Bologna
2022
University of Turin
2008-2021
Institute for Space Astrophysics and Planetology
2020-2021
University of Oxford
2020
We present the results of a pilot JVLA project aimed at studying bulk radio-emitting AGN population, unveiled by NVSS/FIRST and SDSS surveys.We obtained A-array observations 1.4, 4.5, 7.5 GHz for 12 sources SDSS/NVSS sample. The radio maps reveal compact unresolved or slightly resolved structures on scale 1-3 kpc, with only one exception FRI/FRII source extended over $\sim$40 kpc. isolate core component in most them. sample splits into two groups. Four have small black hole (BH) masses...
We report the results of intensive X-ray, UV, and optical monitoring Seyfert 1 galaxy NGC 4593 with Swift. There is no intrinsic flux-related spectral change in any variable component small apparent variations being due to contamination by a constant hard (reflection) X-rays red host UV/optical. Relative shortest wavelength band, UVW2, lags other UV/optical bands mostly agree predictions reprocessing high energy emission an accretion disc. The U-band lag is, however, larger than expected,...
We built a catalog of 122 FR~II radio galaxies, called FRII{\sl{CAT}}, selected from published sample obtained by combining observations the NVSS, FIRST, and SDSS surveys. The includes sources with redshift $\leq 0.15$, an edge-brightened morphology, those at least one emission peaks located radius $r$ larger than 30 kpc center host. luminosity 1.4 GHz \FRII\ covers range $L_{1.4} \sim 10^{39.5} - 10^{42.5}$ $\ergs$. has 90\% low 10\% high excitation galaxies (LEGs HEGs), respectively....
We present the first data release of high-resolution ($\leq0.2$ arcsec) 1.5-GHz radio images 103 nearby galaxies from Palomar sample, observed with eMERLIN array, as part LeMMINGs survey. This sample includes which are active (LINER and Seyfert) quiescent (HII Absorption line galaxies, ALG), reclassified based upon revised emission-line diagrams. detect emission $\gtrsim$ 0.2 mJy for 47/103 (22/34 LINERS, 4/4 Seyferts, 16/51 HII 5/14 ALGs) sizes typically $\lesssim$100 pc. identify core...
Abstract We present the parsec-scale radio spectra of a representative sample 13 Palomar–Green radio-quiet quasars, based on our new Very Long Baseline Array (VLBA) observations at 8.4 and 23.6 GHz earlier VLBA studies 1.5 5.0 GHz. The core emission generally exhibits flat spectrum 1.5–5.0 GHz, which indicates compact optically thick synchrotron source scale smaller than broad-line region (BLR) radius R BLR ∼ 0.01–0.1 pc. 8.4–23.6 spectral slope remains in four objects indicating inner <...
We study a sample of 44 low-luminosity radio-loud AGN, which represent range nuclear radio-power spanning 5 orders magnitude, to unveil the accretion mechanism in these galaxies. estimate rate gas associated with their hot coronae by analyzing archival Chandra data, derive deprojected density and temperature profiles spherical approximation. Measuring jet power from radio-luminosity, we find that correlates linearly power, an efficiency conversion rest mass into ~0.012. These results...
With the aim of exploring properties class FR 0 radio galaxies, we selected a sample 108 compact sources, called FR0 CAT , by combining observations from NVSS, FIRST, and SDSS surveys. We included in catalog sources with redshift ≤0.05, size ≲5 kpc, an optical spectrum characteristic low-excitation galaxies. Their luminosities at 1.4 GHz are range 10 38 ≲ ν L 40 erg s -1 . The hosts mostly (86%) luminous (−21 ≳ M r −23) red early-type galaxies black hole masses 8 BH 9 ⊙ These similar to...
Several studies indicate that radio-loud (RL) Active Galactic Nuclei (AGN) are produced only by the most massive black holes (BH), $M_{\rm BH} \sim 10^8$-$10^{10} M_\odot$. This idea has been challenged discovery of RL Narrow Line Seyfert 1 (RL NLSy1), having estimated masses BH}$$\sim$$10^6$-$10^7$ M$_\odot$. However, these low BH}$ estimates might be due to projection effects. Spectropolarimetry allows us test this possibility looking at NLSy1s under a different perspective, i.e., from...
We present the first intensive continuum reverberation mapping study of high accretion rate Seyfert galaxy Mrk 110. The source was monitored almost daily for more than 200 days with Swift X-ray and UV/optical telescopes, supported by ground-based observations from Las Cumbres Observatory, Liverpool Telescope, Zowada thus extending wavelength coverage to 9100 \r{A}. 110 found be significantly variable at all wavebands. Analysis intraband lags reveals two different behaviours, depending on...
Radio-loud active galaxies have two accretion modes [radiatively inefficient (RI) and radiatively efficient (RE)], with distinct optical infrared signatures, jet dynamical behaviours, which in arcsec- to arcmin-resolution radio surveys manifest primarily as centre- or edge-brightened structures [Fanaroff-Riley (FR) class I II]. The nature of the relationship between mode morphology (FR class) has been subject long debate. We present a comprehensive investigation this for sample 286...
We present the results of Karl G. Jansky Very Large Array (VLA) observations to study properties FR0 radio galaxies, compact sources associated with early-type galaxies which represent bulk local radio-loud AGN population. obtained A-array at 1.5, 4.5, and 7.5 GHz for 18 FR0s from FR0CAT sample: these are $z<0.05$, unresolved in FIRST images spectroscopically classified as low excitation (LEG). Although we reach an angular resolution $\sim$0.3 arcsec, majority is still unresolved. Only four...
The origin of the radio emission in radio-quiet (RQ) quasars is not established yet. Important hints can be provided by spectral slope, and its relation to other properties. We compiled highest resolution 5 8.4 GHz Very Large Array observations available RQ optically selected Palomar–Green (PG) at |$z$| < 0.5. derive 5–8.4 αR, for 25 complete well-studied sample 71 PG quasars. find a highly significant correlation αR with L/LEdd, where high L/LEdd(>0.3) have steep slope (αR −0.5), indicative...
We examine the distribution of radio emission from ~42,000 quasars Sloan Digital Sky Survey, as measured in LOFAR Two-Metre Survey (LoTSS). present a model luminosity that assumes every quasar displays superposition two sources emission: active galactic nuclei (jets) and star-formation. Our two-component provides an excellent match to observed flux density distributions across wide range redshifts optical luminosities; this suggests jet-launching mechanism operates all but with different...
Abstract Radio-loud compact radio sources (CRSs) are characterised by morphological compactness of the jet structure centred on active nucleus galaxy. Most local elliptical galaxies found to host a CRS with nuclear luminosities lower than those typical quasars, $$\lesssim 10^{42}\, \text{erg}\, \text{s}^{-1}$$ <mml:math...
We explore radio and spectroscopic properties of a sample 14 miniature galaxies, i.e. early-type core galaxies hosting radio-loud AGN extremely low power, 10<sup>27-29<sup/> erg s<sup>-1<sup/> Hz<sup>-1<sup/> at 1.4 GHz. Miniature smoothly extend the relationships found for more powerful FR I between emission line, optical nuclear luminosities to lower levels. However, they have deficit factor ~100 in extended with respect that classical example 3CR/FR I. This is not due their luminosity,...
In a previous paper we showed that the radio sources selected by combining large areas and optical surveys, present strong deficit of emission with respect to 3CR radio-galaxies matched in line luminosity. We argued prevalence luminous extended structures high flux limited samples is due selection bias. Sources low power form bulk radio-loud AGN population but are still virtually unexplored. here analyze their photometric spectroscopic properties. From point view lines, majority sample Low...
The physical origin of radio emission in Radio Quiet Active Galactic Nuclei (RQ AGN) remains unclear, whether it is a downscaled version the relativistic jets typical Loud (RL) AGN, or originates from accretion disk. correlation between 5 GHz and X-ray luminosities RQ which follows $L_R = 10^{-5}L_X$ observed also stellar coronae, suggests an association both sources with disk corona. Observing AGN at higher (mm-wave) frequencies, where synchrotron self absorption diminished, smaller regions...
We present a sub-arcsec resolution radio imaging survey of sample 76 low-luminosity active galactic nuclei (LLAGN) that were previously not detected with the Very Large Array at 15 GHz. Compact, parsec-scale emission has been above flux density 40 $\mu$Jy in 60% (45 76) LLAGN sample. detect 20 out 31 (64%) low-ionization nuclear emission-line region (LINER) nuclei, ten 14 (71%) Seyfert galaxies, and (48%) transition objects. use this to explore correlations between different lines...
We built a catalog of 219 FR I radio galaxies (FR Is), called FRICAT, selected from published sample and obtained by combining observations the NVSS, FIRST, SDSS surveys. included in sources with an edge-darkened morphology, redshift ≤ 0.15, extending (at sensitivity FIRST images) to radius r larger than 30 kpc center host. also additional (sFRICAT) 14 smaller (10 < kpc) Is, limiting z 0.05. The hosts FRICAT are all luminous (−21 ≳ Mr −24), red early-type black hole masses range 108 ≲ MBH 3...
mm-wave emission from active galactic nuclei (AGNs) may hold the key to understanding physical origin of their radio cores. The correlation between radio/mm and X-ray luminosity suggest a similar two sources. Since synchrotron self-absorption decreases with frequency, mm-waves probe smaller length-scales than cm-waves. We report on 100 GHz (3 mm) observations Combined Array for Research in Millimeter-wave Astronomy 26 AGNs selected hard Swift/Burst Alert Telescope survey. 20/26 targets were...
The origin of the radio emission in radio-quiet quasars (RQQ) is not established yet. We present new VLBA observations at 1.6 and 4.9 GHz ten RQQ (nine detected), which together with published earlier eight (five forms a representative sample 18 drawn from Palomar-Green low z (< 0.5) AGN. spectral slope integrated extends very steep (alpha < -1.98) to strongly inverted = +2.18), slopes nine 14 objects are flat > -0.5). Most have an unresolved flat-spectrum core, coincides optical Gaia...