A5073454179- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Medical Imaging Techniques and Applications
- Pulsars and Gravitational Waves Research
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
- Calibration and Measurement Techniques
- History and Developments in Astronomy
- Radio Astronomy Observations and Technology
- Statistical and numerical algorithms
- Relativity and Gravitational Theory
- Black Holes and Theoretical Physics
- Scientific Research and Discoveries
- Dark Matter and Cosmic Phenomena
National Observatory of Athens
2015-2024
Osservatorio astronomico di Bologna
2010-2013
Max Planck Institute for Extraterrestrial Physics
2010
Center for Astrophysics Harvard & Smithsonian
2003
Leibniz Institute for Astrophysics Potsdam
2003
European Space Research and Technology Centre
2003
Durham University
1991-2000
University of Leicester
1991-1999
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 the XXL Survey, largest XMM programme totaling some 6.9 Ms to date and involving an international consortium of roughly 100 members. The Survey covers two extragalactic areas 25 deg2 each at a point-source sensitivity ~ 5E-15 erg/sec/cm2 in [0.5-2] keV band (completeness limit). survey's main goals are provide constraints on dark energy equation state from space-time distribution clusters galaxies serve as pathfinder for future, wide-area X-ray missions. review science objectives,...
The first all-sky survey for cosmic sources of extreme-ultraviolet radiation has been carried out with the UK Wide Field Camera on ROSAT. A reduction data yielded a catalogue 383 relatively bright EUV sources, forming WFC Bright Source Catalogue. This represents 30-fold increase in number astrophysical objects detected ~ 60–200 eV energy band and covers flux range, each two bands, more than 2000. search (typically 1-arcmin) error circles using variety catalogues SIMBAD base, identified...
We present the first results of spectroscopy distant, obscured AGN as obtained with ultra-deep (~3.3 Ms) XMM-Newton survey in Chandra Deep Field South (CDFS). One primary goals project is to characterize X-ray spectral properties and heavily Compton-thick over range redhifts luminosities that are relevant terms their contribution background. The exposure, coupled XMM detector's throughput, allowed us accumulate good quality spectra for a large number sources and, particular, at cosmological...
This paper investigates what constraints can be placed on the fraction of Compton-thick (CT) AGN in Universe from modeling spectrum diffuse X-ray background (XRB). We present a model for synthesis XRB that uses as input library spectra generated by Monte Carlo simulations described Brightman & Nandra. is essential to account Compton scattering photons dense medium and impact process obscured AGN. identify small number parameters code which encapsulate minimum level uncertainty reconstructing...
Heavily obscured, Compton Thick (CT, NH>10^24 cm^-2) AGN may represent an important phase in AGN/galaxy co-evolution and are expected to provide a significant contribution the cosmic X-ray background (CXB). Through direct spectra analysis, we selected 39 heavily obscured (NH>3x10^23 2 deg^2 XMM-COSMOS survey. After selecting CT based on fit of simple absorbed two power law model XMM data, presence was confirmed 80% sources using deeper Chandra data more complex models. The final sample...
Models of galaxy evolution assume some connection between the AGN and star formation activity in galaxies. We use multi-wavelength information CDFS to assess this issue. select AGNs from 3Ms XMM-Newton survey measure star-formation rates their hosts using data that probe rest-frame wavelengths longward 20 um. Star-formation are obtained spectral energy distribution fits, identifying subtracting an component. divide by stellar masses derive specific (sSFR) find evidence for a positive...
We combine deep X-ray survey data from the Chandra observatory and wide-area/shallow XMM-XXL field to estimate active galactic nuclei (AGN) luminosity function in redshift range z = 3–5. The sample consists of nearly 340 sources with either photometric (212) or spectroscopic (128) above range. combination shallow fields also provides a baseline three orders magnitude, LX(2–10 keV) ≈ 1043–1046 erg s− 1 at > 3. follow Bayesian approach determine binned AGN space density explore their evolution...
(abridged) The XMM-Newton survey in the Chandra Deep Field South (XMM-CDFS) aims at detecting and studying spectral properties of a significant number obscured Compton-thick AGN. large effective area XMMin 2--10 5--10 keV bands, coupled with 3.45 Ms nominal exposure time, allows us to build clean samples both makes XMM-CDFS deepest XMM currently published band. multi-wavelength spectroscopic coverage CDFS for an immediate abundant scientific return. We present data reduction observations,...
We have used a new sample of 42 QSOs, identified at faint flux limits [S(0.5–2 keV) > 6 ×10–15 erg s–1 cm–2] by the ROSAT satellite, to extend coverage QSO X -ray luminosity function (XLF) low luminosities ( < 1045 s–1) and high redshifts (z 0.5). By combining this with EMSS survey, we confirm that z = 0 XLF exhibits ‘break’ |$L_{\text X}^{*}(0)={10}^{43.9\pm 0.1}$|erg s–1. For q0 universe, obtain steep power-law slope for XLF, |$\Phi ({L}_{\text X})\propto L_{\text X}^{-3.4\pm 0.1}$| above...
We combine bright XMM data with the Chandra Deep Field South observations in order to explore behavior of intrinsic AGN absorption, as a function redshift and luminosity.Our sample consists 359 sources selected hard 2-8 keV band, spanning flux range 6\times10^{-16}-$3\times10^{-13} erg s^-1 cm^-2 high rate spectroscopic or photometric completeness (100 85 per cent respectively for data. derive column density values using X-ray spectral fits. find that fraction obscured falls increasing...
The Chandra Deep Field is the region of sky with highest concentration X-ray data available: 4Ms and 3Ms XMM data, allowing excellent quality spectra to be extracted even for faint sources. We take advantage this in order compile a sample heavily obscured Active Galactic Nuclei (AGN) using spectroscopy. select our among 176 brightest sources, searching either a) flat (Photon index<1.4 at 90% confidence level) suggestive reflection dominated continuum or b) an absorption turn-over column...
We present the spatial clustering properties of 1466 X-ray selected AGN compiled from Chandra CDF-N, CDF-S, eCDF-S, COSMOS and AEGIS fields in 0.5-8 keV band. The sources span redshift interval 0<z<3 have a median value Med{z}=0.976.We employ projected two-point correlation function to infer find length r0= 7.2+-0.6 h^{-1} Mpc slope \gamma=1.48+-0.12, which corresponds bias b=2.26+-0.16. Using two different halo models, we consistently estimate an average dark-matter host mass Mh\sim 1.3...
We present analyses of host galaxy properties type 1 and 2 X-ray selected AGNs in the XMM-XXL field, which have available optical spectroscopic classification. model their to far-infrared spectral energy distributions (SEDs) using X-CIGALE code. allows fitting flux accounts for viewing angle dusty torus attenuation from polar dust. By selecting matched subsamples luminosity redshift parameter space, we find that both types live galaxies with similar star formation. However, AGN tend reside...
In this work, we compare the supermassive black hole (SMBH) and host galaxy properties of X-ray obscured unobscured AGN. For that purpose, used ∼35 000 detected AGN in 4XMM-DR11 catalogue for which there are available measurements their spectral parameters, such as hydrogen column density, N H , photon index, Γ, from XMM2Athena Horizon 2020 European project. We constructed energy distributions (SEDs) sources, calculated via SED fitting analysis, utilising CIGALE code. applied strict...
The X-ray luminosity function (XLF) of active galactic nuclei (AGN) offers a robust tool to study the evolution and growth supermassive black-hole population over cosmic time. Owing limited area probed by surveys, optical surveys are routinely used probe accretion in high-redshift Universe z ≥ 3. However, may be incomplete because they strongly affected dust redenning. In this work we derive XLF its at high redshifts ( 3) using large sample AGN selected different fields with various areas...
We present ROSAT [High Resolution Imager (HRI) and Position Sensitive Proportional Counter (PSPC)] ASCA observations of the two luminous (Lx ∼ 1041−42 erg s−1) star-forming galaxies NGC 3310 3690. The HRI shows clearly that sources are extended with X-ray emission in 3690 coming from at least three regions. combined 0.1–10 keV spectrum can be described by components, a Raymond—Smith plasma temperature kT = 0.81+0.09−0.12 hard power law, Γ 1.44+0.20−0.11 (or alternatively harder 15 keV),...
We present XMM-Newton spectral analysis of all 38 Seyfert galaxies from the Palomar spectroscopic sample galaxies. These are found at distances up to 67 Mpc and cover absorbed 2-10 keV luminosity range ~10^38-10^43 ergs/s. Our aim is determine distribution X-ray absorption in local Universe. Three these Compton-thick with column densities just above 10^24 cm^-2 high equivalent width FeKa lines (>700 eV). Five more sources have low values [OIII] flux ratio suggesting that they could be...
In this paper we investigate the power spectrum of unresolved 0.5–2 keV cosmic X-ray background (CXB) with deep Chandra 4-Msec (Ms) observations in Deep Field South (CDFS). We measured a signal that, on scales >30 arcsec, is significantly higher than shot noise and increasing angular scale. interpreted as joint contribution clustered undetected sources like active galactic nuclei (AGN), galaxies intergalactic medium (IGM). The source fluctuations accounts for ∼12 per cent extragalactic CXB....
We use a combination of the XMM-Newton serendipitous X-ray survey with optical SDSS, and infrared WISE all-sky in order to check efficiency low luminosity selection method finding heavily obscured AGN. select sources 2-8 keV band which have redshift determination SDSS catalogue. match this sample catalogue, fit SEDs 2844 three, or more, photometric data-points infrared. then AGN candidates by comparing their 12 micron observed 2-10 expected intrinsic relation. With approach we find 20...