A5078790470- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Mechanics and Biomechanics Studies
- High-pressure geophysics and materials
- Particle Detector Development and Performance
- Adaptive optics and wavefront sensing
- Advanced X-ray Imaging Techniques
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Particle physics theoretical and experimental studies
- Particle Accelerators and Free-Electron Lasers
- Scientific Measurement and Uncertainty Evaluation
- X-ray Spectroscopy and Fluorescence Analysis
- Superconducting Materials and Applications
- Health and Medical Research Impacts
- Dark Matter and Cosmic Phenomena
University of Southampton
2016-2025
Fermi National Accelerator Laboratory
2021-2024
Inter-University Centre for Astronomy and Astrophysics
2021-2023
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Durham University
2013-2018
Centrum Badań Kosmicznych
2018
Polish Academy of Sciences
2018
Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
2016
Technical University of Denmark
2016
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 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,...
Dust around active galactic nuclei (AGNs) is distributed over a wide range of spatial scales and can be observed in the infrared (IR). It generally assumed that distribution on parsec forms geometrically optically thick entity equatorial plane accretion disk broad-line region—dubbed "dust torus"—that emits bulk subarcsecond-scale IR emission gives rise to orientation-dependent obscuration. However, recent interferometry studies with unprecedented position angle (P.A.) baseline coverage these...
We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on high angular resolution 12 and 18μm continuum fluxes from AGN subarcsecond MIR atlas 2–10 keV 14–195 data collected literature. isolate a sample of 152 objects with reliable nature multi-epoch minimal contribution star formation. Although is not homogeneous or complete, we show that our results are unlikely to be affected by significant biases. The MIR–X-ray nearly...
We present the first subarcsecond-resolution mid-infrared (MIR) atlas of local active galactic nuclei (AGN). Our contains 253 AGN with a median redshift z=0.016, and includes all publicly available MIR imaging performed to date ground-based 8-m class telescopes, total 895 independent measurements. Of these, more than 60% are published here for time. detect extended nuclear emission in at least 21% objects, while another 19% appear clearly point-like, remaining objects cannot be constrained....
Hard X-ray ($\geq 10$ keV) observations of Active Galactic Nuclei (AGN) can shed light on some the most obscured episodes accretion onto supermassive black holes. The 70-month Swift/BAT all-sky survey, which probes 14-195 keV energy range, has currently detected 838 AGN. We report here broad-band (0.3-150 characteristics these AGN, obtained by combining XMM-Newton, Swift/XRT, ASCA, Chandra, and Suzaku in soft band ($\leq with averaged data. non-blazar AGN our sample are almost equally...
Heavily obscured accretion is believed to represent an important stage in the growth of supermassive black holes and play role shaping observed spectrum cosmic X-ray background. Hard (E > 10 keV) selected samples are less affected by absorption than at lower energies, therefore one best ways detect identify Compton-thick (CT, ) active galactic nuclei (AGNs). In this letter we present first results largest broadband (0.3–150 spectral study hard AGNs date, focusing on properties heavily...
We report on observations of NGC1068 with NuSTAR, which provide the best constraints to date its $>10$~keV spectral shape. find no strong variability over past two decades, consistent Compton-thick AGN classification. The combined Chandra, XMM-Newton, and Swift-BAT dataset offers new insights into complex reflected emission. critical combination high signal-to-noise NuSTAR data a spatial decomposition Chandra allow us break several model degeneracies greatly aid physical interpretation. When...
Over three quarters in 2010-2011, Kepler monitored optical emission from four active galactic nuclei (AGN) with ~30 min sampling, >90% duty cycle, and
We present 8-13 micron imaging and spectroscopy of 9 type 1 10 2 AGN obtained with the VLT/VISIR instrument at spatial resolution <100 pc. The emission from host galaxy sources is resolved out in most cases. silicate absorption features are moderately deep shallow. compare mid-IR luminosities to luminosity tracers found that radiation emitted quite isotropically. In two cases, IC5063 MCG-3-34-64, we find evidence for extended dust narrow-line region. confirm correlation between observed...
Recent mid-infrared (MIR) interferometric observations showed in few active galactic nuclei (AGN) that the bulk of infrared emission originates from polar region above putative torus, where only little dust should be present. Here, we investigate whether such strong is common AGN. Out 149 Seyferts MIR atlas local AGN (Asmus et al.), 21 show extended on single dish images. In 18 objects, aligns with system axis position angle, established by [OIII], radio, polarisation and maser based angle...
Abstract Here we study a 1–200 keV energy spectrum of the black hole binary Cygnus X-1 taken with NuSTAR and Suzaku . This is first report observation Cyg in intermediate state, was during part orbit where absorption due to companion’s stellar wind minimal. The includes multi-temperature thermal disk component, cutoff power-law relativistic nonrelativistic reflection components. Our initial fits publicly available constant density models ( relxill reflionx ) lead extremely high iron...
We present simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR ) and Suzaku observations of the X-ray binary Cygnus X-1 in hard state. This is first time this state has been observed Cyg with NuSTAR, which enables us to study reflection broadband spectra unprecedented detail. confirm that iron line cannot be fit a combination narrow lines absorption features, instead requiring relativistically blurred profile from companion wind. use models García et al. simultaneously measure black...
Abstract We present the drastic transformation of X-ray properties active galactic nucleus (AGN) 1ES 1927+654, following a changing-look event. After optical/ultraviolet outburst power-law component, produced in corona, disappeared, and spectrum 1927+65 instead became dominated by blackbody component ( kT ∼ 80–120 eV). This implies that ubiquitously found AGNs, was destroyed Our dense ∼450 days long monitoring shows source is extremely variable band. On timescales varies up to ∼4 dex ∼100...
ABSTRACT We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift /Burst Alert Telescope (BAT) X-ray data. Using NuSTAR , we observe nine high SC-selected AGNs. find high-sensitivity spectra show majority are (78% or 7/9) and remaining two nearly ( N H ≃ (5–8) × 23 cm −2 ). SC BAT measurements consistent, suggesting this technique can be applied future telescopes. tested method on well-known AGNs...
We report on a NuSTAR and XMM-Newton program that has observed sample of three extremely luminous, heavily obscured WISE-selected AGN at z~2 in broad X-ray band (0.1 - 79 keV). The parent sample, selected to be faint or undetected the WISE 3.4um (W1) 4.6um (W2) bands but bright 12um (W3) 22um (W4), are rare, with only ~1000 so-called W1W2-dropouts across extragalactic sky. Optical spectroscopy reveals typical redshifts for this population, implying rest-frame mid-IR luminosities L(6um)~6e46...
We present a NuSTAR and XMM-Newton monitoring campaign in 2014/2015 of the Compton-thick Seyfert 2 galaxy, NGC 1068. During August 2014 observation, we detect with flux excess above 20 keV ($32\pm6 \%$) respect to December 2012 observation later performed February 2015. do not any spectral variation below 10 data. The transient can be explained by temporary decrease column density obscuring material along line sight (from N$_{\rm H}\simeq10^{25}$ cm$^{-2}$ H}=6.7\pm1.0\times10^{24}$...
We report on a first census of Galactic black hole X-ray binary (BHXRB) properties with the second data release (DR2) Gaia, focusing dynamically confirmed and strong candidate BH transients. Gaia DR2 provides five-parameter astrometric solutions including position, parallax proper motion for 11 out sample 24 systems. Distance estimates are tested inversion as well Bayesian inference. derive an empirically motivated characteristic scalelength L = 2.17 ± 0.12 kpc this BHXRB population to infer...
We present X-ray spectral analyses for three Seyfert 2 active galactic nuclei, NGC 424, 1320, and IC 2560, observed by NuSTAR in the 3-79 keV band. The high quality hard spectra allow detailed modeling of Compton reflection component first time these sources. Using quasi-simultaneous Swift/XRT data, as well archival XMM-Newton we find that all nuclei are obscured Compton-thick material with column densities excess ~5 x $10^{24}$ cm$^{-2}$, their above 3 dominated intrinsic continuum on...
We present the first results of Galaxy Activity, Torus and Outflow Survey (GATOS), a project aimed at understanding properties dusty molecular tori their connection to host galaxy in nearby Seyfert galaxies. Our expands range AGN luminosities Eddington ratios covered by previous surveys Seyferts conducted ALMA allows us study gas feeding feedback cycle combined sample 19 Seyferts. used obtain new images emission dust using CO(3-2) HCO+(4-3) lines as well underlying continuum 870 microns with...
MAXI J1820+070 (optical counterpart ASASSN-18ey) is a black hole candidate discovered through its recent very bright outburst. The low extinction column and long duration at high flux allow detailed measurements of the accretion process to be made. In this work, we compare evolution X-ray spectral timing properties initial hard state We show that inner disc, as measured by relativistic reflection, remains steady throughout period Nevertheless, subtle variability observed, which well...
The XMM Large Scale Structure survey (XMM-LSS) is a medium deep large area X-ray survey. Its goal to extend scale structure investigations attempted using ROSAT cluster samples two redshift bins between 0<z<1 while maintaining the precision of earlier studies. Two main goals have constrained design: evolutionary study cluster–cluster correlation function and number density. adopted observing configuration consists an equatorial mosaic 10 ks pointings, separated by covering 8° × 8°, giving...
Many Active Galactic Nuclei (AGN) are surrounded by gas which absorbs the radiation produced accretion onto central black hole and obscures nucleus from direct view. The dust component of greatly enhances effect pressure above that for Thomson scattering so an AGN is sub-Eddington ionized in usual sense can appear super-Eddington cold dusty gas. radiation-pressure enhancement factor depends on spectrum but ranges between unity about 500, depending column density. It means absorption...