Books by Volker Beckmann
The book gives an overview on the current knowledge of the Active Galactic Nuclei phenomenon. The... more The book gives an overview on the current knowledge of the Active Galactic Nuclei phenomenon. The spectral energy distribution will be discussed, pointing out what can be observed in different wavebands and with different physical models. Furthermore, the authors discuss the AGN with respect to its environment, host galaxy, feedback in galaxy clusters, etc. and finally the cosmological evolution of the AGN phenomenon.
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra, XMM-Newton, Swift, and INTEGRAL not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring, and also discusses the very high energy (VHE) regime. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities.
Papers by Volker Beckmann
HAL (Le Centre pour la Communication Scientifique Directe), May 1, 2017
Context. Blazars are the most luminous and variable active galactic nuclei (AGNs), and thus excel... more Context. Blazars are the most luminous and variable active galactic nuclei (AGNs), and thus excellent probes of accretion and emission processes close to the central engine. Aims. We concentrate here on PKS 1510-089 (z = 0.36), a member of the Flat-Spectrum Radio Quasar variety of blazars, an extremely powerful gamma-ray source and one of the brightest in the Fermi LAT catalog, to study the complex variability of its bright multiwavelength spectrum, identify the physical parameters responsible for the variations and the time scales of possible recurrence and quasi-periodicity at high energies. Methods. PKS 1510-089 was observed twice in hard X-rays with the IBIS instrument onboard INTEGRAL during the flares of Jan 2009 and Jan 2010, and simultaneously with Swift and the Nordic Optical Telescope (NOT), in addition to the constant Fermi monitoring. We also measured the optical polarization in several bands on 18 Jan 2010 at the NOT. Using these and archival data we constructed historical light curves at gamma-to-radio wavelengths covering nearly 20 years and applied tests of fractional and correlated variability. We also assembled spectral energy distributions (SEDs) based on these data and compared them with those at two previous epochs, by applying a model based on synchrotron and inverse Compton radiation from blazars. Results. The modeling of the SEDs suggests that the physical quantities that undergo the largest variations are the total power injected into the emitting region and the random Lorentz factor of the electron distribution cooling break, that are higher in the higher gammaray states. This suggests a correlation of the injected power with enhanced activity of the acceleration mechanism. The cooling likely takes place at a distance of ∼1000 Schwarzschild radii (∼0.03 pc) from the central engine, i.e much smaller than the broad line region (BLR) radius. The emission at a few hundred GeV can be reproduced with inverse Compton scattering of highly relativistic electrons off far-infrared photons if these are located much farther than the BLR, i.e., around 0.2 pc from the AGN, presumably in a dusty torus. We determine a luminosity of the thermal component due to the inner accretion disk of L d 5.9 × 10 45 erg s −1 , a BLR luminosity of L BLR 5.3 × 10 44 erg s −1 , and a mass of the central black hole of M BH 3 × 10 8 M. The fractional variability as a function of wavelength follows the trend expected if X-and gamma-rays are produced by the same electrons as radio and optical photons, respectively. Discrete Correlation Function (DCF) analysis between the long-term Steward observatory optical V-band and gamma-ray Fermi LAT light curves yields a good correlation with no measurable delay. Marginal correlation where X-ray photons lag both optical and gamma-ray ones by time lags between 50 and 300 days is found with the DCF. Our time analysis of the RXTE PCA and Fermi LAT light curves reveals no obvious (quasi-)periodicities, at least up to the maximum time scale (a few years) probed by the light curves, which are severely affected by red noise.
Coordinating central-western Europe's plug-in to the European Open Science Cloud is a challen... more Coordinating central-western Europe's plug-in to the European Open Science Cloud is a challenge. But through the collaboration of key players, the foundations have been established through EOSC-Pillar within its first year. Read about the main updated from the EOSC-Pillar projects: EOSC-Pillar, One Year On The National Initiatives Survey and its Importance Austria, Belgium, France, Germany, and Italy - Working towards an EOSC Federated FAIR Data Space - A Space to Federate them all The Project in Numbers Look into the Future
EOSC-Pillar invited 2,204 organisations (funding bodies, universities, research infrastructures, ... more EOSC-Pillar invited 2,204 organisations (funding bodies, universities, research infrastructures, and e-infrastructures) in five countries (Austria, Belgium, France, Germany, Italy) to participate in the 'National Initiatives' Survey. 688 representatives (31%) responded to the survey and answered various questions on business models, sustainability, users, Service Level Agreements (SLAs), access to data and services, FAIRness of data, data management in repositories, regulations on open science and open data as well as on perceptions of EOSC. This document contains the main results in terms of frequency analysis.
The unification of X-ray and radio selected BL Lacs has been an outstanding problem in the blazar... more The unification of X-ray and radio selected BL Lacs has been an outstanding problem in the blazar research in the past years. Recent investigations have shown that the gap between the two classes can be filled with intermediate objects and that apparently all differences can be explained by mutual shifts of the peak frequencies of the synchrotron and inverse Compton component of the emission. We study the consequences of this scheme using a new sample of X-ray selected BL Lac objects comprising 104 objects with z < 0.9 and a mean redshift z = 0.34. 77 BL Lacs, of which the redshift could be determined for 64 (83%) objects, form a complete sample. The new data could not confirm our earlier result, drawn from a subsample, that the negative evolution vanishes below a synchrotron peak frequency log ν peak = 16.5. The complete sample shows negative evolution at the 2σ level (Ve/Va = 0.42 ± 0.04). We conclude that the observed properties of the HRX BL Lac sample show typical behaviour for X-ray selected BL Lacs. They support an evolutionary model, in which flat-spectrum radio quasars (FSRQ) with high energetic jets evolve towards low frequency peaked (mostly radio-selected) BL Lac objects and later on to high frequency peaked (mostly X-ray selected) BL Lacs.
This document presents the results of the public consultation for the proposed readiness indicato... more This document presents the results of the public consultation for the proposed readiness indicators that were collected during the two rounds of consultation as a questionnaire. It is a follow up of the earlier report, "Working Proposal for Living Indicators to Monitor Member States Progresses towards EOSC Readiness", which presents the results of the first round of consultations that took place as an open survey during the session of "National Policy Developments Supporting EOSC Implementation" during the EOSC-hub Week on 20 May 2020. This report also discusses the usefulness of an initial set of indicators proposed as well as discussing the responsibility for monitoring progress against indicators. This document suggests a response to the question: "How can we monitor the status and progresses of MS and AC towards the EOSC implementation and identify opportunities and areas of improvement?" Many practical issues must still be progressed, such as the f...
Full edition for scientific use. The EOSC-Pillar ”National Initiatives” Survey is a cross-section... more Full edition for scientific use. The EOSC-Pillar ”National Initiatives” Survey is a cross-section study in Austria, Belgium, France, Germany, and Italy. The survey aims at landscaping national initiatives of open research data and services with relevance to the European Open Science Cloud (EOSC). Four target groups are part of the study: e-infrastructures, research infrastructures, universities and funding bodies. The survey contains questions on the perception of EOSC as well as detailed questions assessing e.g. the e-infrastructures’ business models, technical characteristics, access conditions, FAIRness of the data holdings and adopted policies related to open science.
Proceedings of the International Astronomical Union, 2018
Radio galaxies provide excellent laboratories for investigating the physical aspects, unification... more Radio galaxies provide excellent laboratories for investigating the physical aspects, unification and cosmic evolution of active galactic nuclei (AGN). Thanks to recent multiwavelength observations, we are now able to separate many different physical components of radio galaxies through imaging and spectroscopy. Observations from radio through X-ray wavelengths can probe the ejection of matter into jets and monitor decades of jet evolution. Gamma-ray observations have shown that radio galaxies are detectable up to the very-high-energy range despite unfavorable jet alignment. We observe radio galaxies out to redshifts greater than z = 5, which makes them important cosmological probes. Planck maps have provided us with new insights into the populations of radio galaxies and their distributions in space in the 30 − 900 GHz range. NuSTAR provides high-quality spectra in the hard X-ray range. The Event Horizon Telescope (EHT) has begun mapping close to the event horizon of the Milky Way's central black hole, and the Square Kilometre Array (SKA), the next generation of extremely large telescopes (ELTs) and other future telescopes will open up a new and vast discovery space. Focus Meeting #3 brought together multiwavelength observers and theorists to synthesize progress made over the last three years and to define future directions. In order to channel the presentations and discussions, the meeting was organized into five sessions: • During the first session, starting on August 22nd, we discussed the radio-galaxy structures that are produced on kiloparsec scales and beyond, with an emphasis on plasma composition, and sought to address their underlying causes. Daniel Schwartz (Harvard-Smithsonian Center for Astrophysics, USA) talked about high-resolution studies of 100 kpc jets based on data from the Chandra X-ray Observatory. For example, a new Chandra survey for jets in radio quasars at z > 3 has revealed X-ray jets and lobes extending beyond the region of detected radio emission (Schwartz 2018). • The second session focused on the central engine and production of the jet(s). Alexander Tchekhovskoy (University of California, Berkeley, USA) introduced the topic with a presentation about how numerical simulations incorporating general relativity and magnetism allow us to use black hole accretion phenomena to quantitatively probe strong-field gravity and constrain black hole physics in various astrophysical contexts. • On the second day of the meeting we first discussed populations and statistics of radio galaxies, motivated by a review from Elaine Sadler (University of Sydney, Australia) focusing on results from multi-wavelength radio surveys. • This was followed by a session about future prospects. Lindy Blackburn (Harvard-Smithsonian Center for Astrophysics, USA) started the discussion with a presentation on the goals and status of the EHT, which has already revealed structure on the scale of † This article was originally published with its supplementary material missing. This has since been updated in the online PDF and HTML versions and a correction notice has been published.
VizieR Online Data Catalog, Mar 1, 2007
Computing and Software for Big Science, 2017
The astronomer's telegram, 2015
NTEGRAL Galactic bulge monitoring observations (ATel #438) on UT 13 September 2015 18:50-22:32 re... more NTEGRAL Galactic bulge monitoring observations (ATel #438) on UT 13 September 2015 18:50-22:32 reveal renewed X-ray activity from the low-mass X-ray binary transient and Type I X-ray burster SAX J1750.8-2900 (IAU Circ. #6597). The last outburst from this source was reported in 2011 (ATels #3170, 3181).
A new season of the INTEGRAL Galactic Bulge monitoring program (see ATels #438, #874, #1005; Kuul... more A new season of the INTEGRAL Galactic Bulge monitoring program (see ATels #438, #874, #1005; Kuulkers et al. 2007, A&A 466, 595) started, with observations on UT 11 Feb 2008, 16:33-18:07. We here report on results from three currently active transient sources. The IBIS/ISGRI and JEM-X1 images show a bright source near GX 3+1, coincident with the position of the
Monthly Notices of the Royal Astronomical Society, 2015
We study the contribution of thermal and non-thermal processes to the inverse Compton emission of... more We study the contribution of thermal and non-thermal processes to the inverse Compton emission of the radio galaxy M87 by modelling its broad-band emission. Through this we aim to derive insight into where within the AGN the X-ray, γ-ray and VHE emission is produced. We have analysed all available INTEGRAL IBIS/ISGRI (Imager on Board INTEGRAL Spacecraft/INTEGRAL Soft Gamma-Ray Imager) data on M87, spanning almost 10 years, to set an upper limit to the average hard X-ray flux of f (20-60 keV) 3 × 10 −12 erg cm −2 s −1 , using several techniques beyond the standard analysis which are also presented here. We also analysed hard X-ray data from Suzaku/PIN taken late 2006 November, and we report the first hard X-ray detection of M87 with a flux of f (20-60 keV) = 10 −11 erg cm −2 s −1. In addition we analyse data from Fermi/Large Area Telescope, INTEGRAL/Joint European Monitor in X-rays, and Suzaku/X-ray Imaging Spectrometer. We collected historical radio/IR/optical and VHE data and combined them with the X-ray and γ-ray data, to create broad-band spectral energy distributions (SEDs) for the average low-flux state and the flaring state. The resulting SEDs are modelled by applying a single-zone SSC model with a jet angle of θ = 15 •. We also show that modelling the core emission of M87 using a single-zone synchrotron self-Compton model does represent the SED, suggesting that the core emission is dominated by a BL Lactype AGN core. Using SED modelling we also show that the hard X-ray emission detected in 2006 is likely due to a flare of the jet knot HST-1, rather than being related to the core.
The IBIS/ISGRI and the JEM-X1 instrument aboard INTEGRAL discovered a new X-ray source during an ... more The IBIS/ISGRI and the JEM-X1 instrument aboard INTEGRAL discovered a new X-ray source during an observation of the inner Galactic disk conducted from 2009 March 18 at 18:37 UT to March 19, 6:22 UT. The new source, IGR J18284-0345 was detected at RA=277.114, DEC=-3.764 (J2000) in the 20-40 keV energy band by ISGRI with 6.3 sigma detection significance for 27
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Books by Volker Beckmann
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra, XMM-Newton, Swift, and INTEGRAL not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring, and also discusses the very high energy (VHE) regime. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities.
Papers by Volker Beckmann
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra, XMM-Newton, Swift, and INTEGRAL not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring, and also discusses the very high energy (VHE) regime. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities.