A. Comastri
A5064367137- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Pulsars and Gravitational Waves Research
- Astrophysics and Star Formation Studies
- Particle Accelerators and Free-Electron Lasers
- Adaptive optics and wavefront sensing
- X-ray Spectroscopy and Fluorescence Analysis
- Radio Astronomy Observations and Technology
- Calibration and Measurement Techniques
- Advanced X-ray Imaging Techniques
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Dark Matter and Cosmic Phenomena
- High-pressure geophysics and materials
- Medical Imaging Techniques and Applications
- Cosmology and Gravitation Theories
- Mechanics and Biomechanics Studies
- History and Developments in Astronomy
- Scientific Measurement and Uncertainty Evaluation
Osservatorio di Astrofisica e Scienza dello Spazio
2018-2025
Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna
2019-2024
National Institute for Astrophysics
2008-2022
Osservatorio astronomico di Bologna
2010-2022
University of Bologna
1996-2022
European Organization for Nuclear Research
2022
Max Planck Society
2010-2019
Max Planck Institute for Astronomy
2019
Max Planck Institute for Radio Astronomy
2016
Max Planck Innovation
2010
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 2012 June 13, is the first focusing high-energy X-ray telescope in orbit. NuSTAR operates band from 3 to 79 keV, extending sensitivity of far beyond ∼10 keV cutoff achieved by all previous satellites. inherently low background associated with concentrating light enables probe hard sky a more than 100-fold improvement over collimated or coded mask instruments that have operated this bandpass. Using its unprecedented...
We collect data at well-sampled frequencies from the radio to γ-ray range for following three complete samples of blazars: Slew survey, 1-Jy BL Lacs and 2-Jy sample flat-spectrum radio-loud quasars (FSRQs). The fraction objects detected in γ-rays (E ≳ 100 MeV) is ∼ 17, 26 40 per cent respectively. Except survey sample, sources do not differ either other each or all sources, terms distributions redshift, X-ray luminosities broad-band spectral indices (radio optical X-ray). compute average...
We present a detailed and self-consistent modeling of the cosmic X-ray background (XRB) based on most up-to-date luminosity functions (XLF) evolution Active Galactic Nuclei (AGN). The large body observational results collected by soft (0.5–2 keV) hard (2–10 surveys are used to constrain at best properties Compton-thin AGN population its contribution XRB emission. number ratio R between moderately obscured (Compton-thin) unobscured is fixed comparison XLFs, which suggests that decreases from...
The phenomenology of gamma-ray bright blazars can be accounted for by a sequence in the source power and intensity diffuse radiation field surrounding relativistic jet. Correspondingly, equilibrium particle distribution peaks at different energies. This leads to trend observed properties: an increase corresponds to: 1) decrease frequencies synchrotron inverse Compton peaks; 2) ratio powers high low energy spectral components. Objects along this would observationally classified respectively...
We present imaging data and photometry for the COSMOS survey in 15 photometric bands between 0.3 2.4 μm. These include taken on Subaru 8.3 m telescope, KPNO CTIO 4 telescopes, CFHT 3.6 telescope. Special techniques are used to ensure that relative calibration is better than 1% across field of view. The absolute accuracy from standard-star measurements found be 6%. corrected using galaxy spectra, providing colors accurate 2% or better. Stellar counts agree well with expected values. Finally,...
Radio and far infrared luminosities of star-forming galaxies follow a tight linear relation. Making use ASCA BeppoSAX observations well-defined sample nearby galaxies, we argue that relations hold between the X-ray, radio luminosities. The effect intrinsic absorption is investigated taking NGC 3256 as test case. It suggested hard X-ray emission directly related to Star Formation Rate. formation processes may also account for most 2–10 keV from LLAGNs lower (for same FIR luminosity). Deep...
The Spitzer-COSMOS survey (S-COSMOS) is a Legacy program (Cycles 2+3) designed to carry out uniform deep of the full 2 sq deg COSMOS field in all seven Spitzer bands (3.6, 4.5, 5.6, 8.0, 24.0, 70.0, 160.0 u). This paper describes parameters, mapping strategy, data reduction procedures, achieved sensitivities date, and complete set for future reference. We show that observed infrared backgrounds S-COSMOS are within 10% predicted background levels. fluctuations at 24u have been measured do not...
[abridged] We present point-source catalogs for the 4Ms Chandra Deep Field-South (CDF-S), which is deepest survey to date and covers an area of 464.5 arcmin^2. provide a main source catalog, contains 740 X-ray point sources that are detected with wavdetect at false-positive probability threshold 1E-5 also satisfy binomial-probability source-selection criterion P<0.004; this approach designed maximize number reliable detected. A total 300 main-catalog new compared previous 2Ms CDF-S sources....
The Cosmic Evolution Survey (COSMOS) was initiated with an extensive allocation (590 orbits in Cycles 12-13) using the Hubble Space Telescope (HST) for high resolution imaging. Here we review characteristics of HST imaging Advanced Camera Surveys (ACS) and parallel observations NICMOS WFPC2. A square field (1.8$\sq$\deg) has been imaged single-orbit ACS I-F814W exposures 50% completeness sources 0.5\arcsec diameter at I$_{AB} $ = 26.0 mag. is a key part COSMOS survey, providing very...
This White Paper, submitted to the recent ESA call for science themes define its future large missions, advocates need a transformational leap in our understanding of two key questions astrophysics: 1) How does ordinary matter assemble into scale structures that we see today? 2) do black holes grow and shape Universe? Hot gas clusters, groups intergalactic medium dominates baryonic content local Universe. To understand astrophysical processes responsible formation assembly these structures,...
We present X-ray source catalogs for the $\approx7$ Ms exposure of Chandra Deep Field-South (CDF-S), which covers a total area 484.2 arcmin$^2$. Utilizing WAVDETECT initial detection and ACIS Extract photometric extraction significance assessment, we create main catalog containing 1008 sources that are detected in up to three bands: 0.5-7.0 keV, 0.5-2.0 2-7 keV. A supplementary is also provided including 47 lower-significance have bright ($K_s\le23$) near-infrared counterparts. identify...
The COSMOS-Legacy survey is a 4.6 Ms Chandra program that has imaged 2.2 deg$^2$ of the COSMOS field with an effective exposure $\simeq$160 ks over central 1.5 and $\simeq$80 in remaining area. combination 56 new observations, obtained as X-ray Visionary Project, previous C-COSMOS survey. We describe reduction analysis observations properties 2273 point sources detected above spurious probability 2$\times 10^{-5}$. also present updated data. whole includes 4016 (3814, 2920 2440 full, soft...
The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program that has imaged the central 0.5 sq.deg of field (centered at 10h, +02deg) with an effective exposure ~160ksec, and outer 0.4sq.deg. area ~80ksec. limiting source detection depths are 1.9e-16 erg cm(-2) s(-1) in Soft (0.5-2 keV) band, 7.3e(-16) cm^-2 s^-1 Hard (2-10 5.7e(-16) Full (0.5-10 band. Here we describe strategy, design execution C-COSMOS survey, present catalog 1761 point sources detected probability being...
Bolometric luminosities and Eddington ratios of both X-ray selected broad-line (Type-1) narrow-line (Type-2) AGN from the XMM-Newton survey in COSMOS field are presented. The sample is composed by 929 (382 Type-1 547 Type-2 AGN) it covers a wide range redshifts, absorbing column densities. About 65% sources spectroscopically identified as either or (83% 52% respectively), while accurate photometric redshifts available for rest sample. study such large with high quality multi-wavelength...
We present new photometry of 16 local Seyferts including 6 Compton-thick sources in <i>N<i/>-band filters around 12-<i>μ<i/>m, obtained with the VISIR instrument on 8-m Very Large Telescope. The near-diffraction-limited imaging provides least-contaminated core fluxes for these to date. Augmenting our previous observations and published intrinsic X-ray fluxes, we form a total sample 42 which find strong mid-infrared:X-ray (12.3 <i>μ<i/>m:2–10 keV) luminosity correlation. Performing...
We present the first set of XMM-Newton EPIC observations in 2 square degree COSMOS field. The strength project is unprecedented combination a large solid angle and sensitivity over whole multiwavelength spectrum. are very efficient localizing identifying active galactic nuclei (AGN) clusters as well groups galaxies. One primary goals Cosmos survey to study co-evolution function their environment Cosmic web. Here we log observations, images summary research highlights for pass 25 pointings...
We report on the measurement of physical properties (rest-frame K-band luminosity and total stellar mass) hosts 89 broad-line (type-1) active galactic nuclei (AGNs) detected in zCOSMOS survey redshift range 1 < z 2.2. The unprecedented multi-wavelength coverage field allows us to disentangle emission host galaxy from that nuclear black hole their spectral energy distributions (SEDs). derive an estimate masses through analysis broad Mg ii lines observed medium-resolution spectra taken with...
It is well accepted that unabsorbed as absorbed active galactic nuclei (AGNs) are needed to explain the nature and shape of Cosmic X-ray background (CXB), even if fraction highly objects (dubbed Compton-thick sources) still substantially escapes detection. We derive analyze absorption distribution using a complete sample AGNs detected by Swift–BAT in first three years survey. The represents only 4.6% total AGN population Swift–BAT. However, we show once corrected for bias against detection...
We report the final optical identifications of medium-depth (∼60 ks), contiguous (2 deg2) XMM-Newton survey COSMOS field. has detected ∼1800 X-ray sources down to limiting fluxes ∼5 × 10−16, ∼3 10−15, and ∼7 10−15 erg cm−2 s−1 in 0.5–2 keV, 2–10 5–10 keV bands, respectively (∼1 ∼6 ∼1 10−14 s−1, three respectively, over 50% area). The work is complemented by an extensive collection multiwavelength data from 24 μm UV, available survey, for each sources, including spectroscopic redshifts ≳50%...
We study the incidence of nuclear obscuration on a complete sample 1310 active galactic nuclei (AGN) selected basis their rest-frame 2–10 keV X-ray flux from XMM-COSMOS survey, in redshift range 0.3 < z 3.5. classify AGN as obscured or unobscured either optical spectral properties and overall SED shape spectrum. The two classifications agree about 70 per cent objects, remaining 30 can be further subdivided into distinct classes: at low luminosities do not always show signs broad lines...
In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of Cosmic Evolution Survey (COSMOS) field. The availability a large training set spectroscopic that extends faint magnitudes enabled comparable highest quality results presently available normal galaxies. We demonstrate morphologically extended, X-ray without optical variability are more accurately described by library galaxies (corrected emission lines) than active...
Using the wide multi-band photometry available in COSMOS field we explore host galaxy properties of a large sample Active Galactic Nuclei (AGN) obtained by combining X-ray and optical spectroscopic selections. Based on careful study their Spectral Energy Distribution (SED), which has been parametrized using 2-component (AGN+galaxy) model fit, derived dust-corrected rest-frame magnitudes, colors, stellar masses star formation rates (SFRs). We find that AGN hosts span range SFRs. No...
The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, program that has imaged the central 0.9 deg2 of field down to limiting depths 1.9 × 10−16 erg cm−2 s−1 in soft (0.5–2 keV) band, 7.3 hard (2–10 and 5.7 full (0.5–10 band. In this paper we report i, K, 3.6 μm identifications 1761 X-ray point sources. We use likelihood ratio technique derive association optical/infrared counterparts for 97% For most remaining 3%, presence multiple or faintness possible counterpart prevented unique...
AGN-driven outflows are invoked by galaxy evolutionary models to quench star formation and explain the origin of relations observed locally between super massive black holes their host galaxies. This work aims detect presence extended ionised in luminous quasars where we expect maximum activity both hole accretion. Currently, there only a few studies based on spatially resolved observations at high redshift, $z>2$. We analyse sample six (${\rm L>10^{47} \ erg/s}$) $z\sim2.4$, H-band using...
ABSTRACT We present the catalog of optical and infrared counterparts Chandra COSMOS-Legacy Survey, a 4.6 Ms program on 2.2 deg 2 COSMOS field, combination 56 new overlapping observations obtained in Cycle 14 with previous C-COSMOS survey. In this Paper we report i , K 3.6 μ m identifications 2273 X-ray point sources detected observations. use likelihood ratio technique to derive association optical/infrared (IR) for 97% sources. also update information 1743 C-COSMOS, using not available when...