The cruise phase of SRG to L2 was used to verify that all eROSITA systems had survived launch and no degradation in the functionality was present. The critical one-time operations of opening the telescope cover and cooling the CCD detectors to -90°C were also carried out during this phase.
This talk presents an overview of the telescope operations during the commissioning phase that verified...
The power of eROSITA, the core instrument on the Russian-German SRG mission, is high sensitivity at high spectral, spatial, and temporal resolution over a large field of view. This is achieved by combining 7 coaligned fast X-ray optics, each composed of 54 mirror shells, to focus the X-rays onto a total of 1 million pixels, which can all be used as spectrographs. On their way to the CCDs, the...
We present results of extensive calibration program performed with ART-XC telescope during the first months of SRG operation. Performance of the ART-XC detectors was calibrated with use of onboard radioactive source while effective area and
point spread function were verified during observations of bright X-ray sources. The derived detector energy resolution of 9% at 14 keV is in good...
During each ground station contact of Spectrum X-Gamma, about once every 24h, eROSITA data are telemetered to ground and then immediately subjected to a quick scientific and engineering analysis - the Near Real Time Analysis. The purpose of the scientific analysis done by the NRTA is to identify new transient or strongly variable sources which were detected with eROSITA and to monitor sources...
The eROSITA Ground Segment team has developed a software package (eSASS - eROSITA Science Analysis Software System) for creating calibrated science data products and for performing various interactive data analysis tasks. The eSASS package builds on experience and in part on code from XMM-Newton and ROSAT, though with significant revisions and upgrades. eROSITA telemetry data received during...
The overview of SRG/ART-XC data reduction procedures and source detection algorithms will be presented. Efficiency of various source detection methods will be compared using the results of realistic SRG/ART-XC all sky survey simulations. The construction and properties of X-ray source catalogue, obtained from the first months of SRG/ART-XC all sky X-ray survey started on Dec 8, 2019 will be discussed.
We demonstrate here the timing capabilities of the ART-XC telescope
on the time scale from several milliseconds to few seconds. The work was done
based on the data of observations of several pulsars emitting in X-rays. The
observations were carried out during the in-flight Calibration and
the performance verification (PV) phases. Using these data we tested
the stability of the on-board clock...
We summarize the properties of the eROSITA camera background at L2,
as a function of camera, time, energy, position on detector,
position in orbit, etc.
The Astronomical Roentgen Telescope – X-ray Concentrator (ART-XC) is one of two X-ray telescopes onboard the SRG mission launched on July 13, 2019 from Baikonur. ART-XC consists of seven co-aligned mirror modules coupled with seven focal plane CdTe double-sided strip detectors. The ART-XC detectors operate in the energy range from 4 keV to over than 100 keV, while the effective area of the...
The growth of supermassive black holes (SMBHs) over cosmic time is imprinted in their X-ray luminosity that is emitted from the inner central engine of active galactic nuclei (AGN). Observationally, X-rays from AGN can be probed both through deep and wide X-ray surveys, and also through the integrated emission that makes up the cosmic X-ray background (CXB). I will give an overview of our...
eFEDS (the eROSITA Final Equatorial Depth Survey) is a CalPV program of the German eROSITA consortium. Using a field-scan observing strategy, eFEDS covers an area of approximately 130 deg^2 in an equatorial field with comprehensive mult-wavelength coverage, notably with Subaaru HSC, VISTA/VIKING and the GAMA spectroscopic survey. With a total exposure time of around 400ks, eFEDS achieves the...
I will present, on behalf of eroAGN and eROFollow-up WGs the multiwavelength counterparts to the eROSITA sources in eFEDS, including their classification (AGN/star). The talk will also cover predictions on our capability to identify the correct counterparts as a function of Ancillary data coverage and depth of X-ray survey (eRASS:1-8).
As matter accretes onto the central supermassive black holes in active galactic nuclei (AGNs), X-rays are emitted. We present a population synthesis model that accounts for the summed X-ray emission from growing black holes; modulo the efficiency of converting mass to X-rays, this is effectively a record of the accreted mass. We need this population synthesis model to reproduce observed...
We present SRGz - a programming package for doing effective optical cross-match, photometric classification and probabilistic photo-z measurements of SRG extragalactic sources. SRGz is based on competitive empirical machine learning (ML) algorithms: quantile random forest, gradient boosting, deep neural networks. ML-models were trained on SDSS spectral samples of quasars, galaxies and stars...
Nearly all galaxies appear to harbor a supermassive black hole. The origin and properties of initial black hole seeds that grow to produce the detected supermassive black hole population are unconstrained at present, as actively growing seeds are not directly observable near their birth epochs. Nevertheless, some unique signatures of seeding survive and can be discerned in: local scaling...
We discuss the first results of the optical identification the SRG X-ray sources of the 18.5 square degrees Lockman Hole PV-phase survey. We show first spectroscopically confirmed quasar candidates at z~4 the spectra of which were obtained at the 1.6-m telescope AZT-33IK and the 6-m telescope BTA.
We review a fraction of optical identification of X-ray sources in the several wide field broad...
The Astronomical Roentgen Telescope X-ray Concentrator (ART-XC) instrument onboard the Spectrum Röntgen Gamma (SRG) mission has started the all-sky hard X-ray survey since 2019/12/08. The observations of the ecliptic pole regions will reach exceptional depth thanks to the survey design of overlapping exposure in these regions. In anticipation of the ART-XC survey in the North Ecliptic Pole...
Several pieces of evidence have been pilling up in the literature leading towards an evolutionary scenario for AGN, moving past the standard unified model. Part of this amounting evidence is the little overlap of AGN samples selected with various identification criteria. Given the rarity of the AGN population, large and complete samples are needed to assess such an evolutionary model and...
In this report we will present first results of the optical identifications by using 1.5-m Russian-Turkish telescope of the sample of X-Ray sources detected with eRosita and ART-XC onboard SRG in the Lockman Hole region during PV period in November 2019. We will inform also results of SRG orbit's astrometric support observations by using RTT-150 in the period July 2019 - February 2020.
eROSITA mission will soon produce an unprecedented number of galaxy clusters, which in turn should help improve X-ray based cosmological measurements. However, in order to use the eROSITA data for precision cosmology, we must improve our understanding of the physics of X-ray emitting intracluster medium (ICM) and develop techniques to control associated systematic uncertainties in cluster mass...
Constraints on cosmology from cluster number count strongly depend on the accuracy of cluster masses which are sensitive to the dynamical state of clusters, thus it is of importance to be able to measure accurately the dynamical state of each cluster. eROSITA telescope on board of Spectrum-Roentgen-Gamma (SRG) mission was launched in July 2019. eROSITA's large effective area, good spatial...
X-ray surveys such as those conducted by eROSITA are a powerful way to identify large
numbers of galaxy clusters. But cluster candidates identified by eROSITA need additional confirmation and redshifts to provide a clean cluster catalog that can be used for science.
Modern optical imaging surveys such as HSC, DES and the Legacy Survey cover large fractions of the eROSITA extragalactic sky and...
Accurate and precise mass measurements of clusters of galaxies are critical for constraining cosmology with cluster number counts from eROSITA. Much progress has been made in measuring cluster masses from X-rays (assuming hydrostatic equilibrium), weak gravitational lensing, and galaxy dynamics, but systematic differences between the methods still remain at the tens of percent level. We will...
The IllustrisTNG simulations produce an unprecedented sample of thousands of well-resolved galaxies within halos of total mass above 10^13 solar masses. TNG is a series of gravo-magnetohydrodynamical cosmological volumes which enable us to simultaneously resolve the internal structure of galaxies at ~hundred parsec scales, while also capturing the full diversity of entire galaxy populations....
I will give an overview of Sunyaev-Zel'dovich (SZ) cluster surveys, the resultant cosmological constraints, and projected future results. Since the first SZ-discovered cluster in 2008, there are now over 1500 SZ-selected clusters reported in the literature. Ongoing surveys from AdvACT and SPT-3G promise to deliver samples with several thousand additional clusters in the next few years, with...
The recent combination of deep Sunyaev Zel'dovich (SZ) surveys with pointed X-ray follow-up has enabled the study of the intracluster medium across most of cosmic time. In particular, within the South Pole Telescope (SPT) collaboration, we have been utilizing Chandra and XMM-Newton follow-up of SPT-selected clusters to study the evolution of the dynamical state, the cooling/heating balance,...
The properties of the hot medium at the periphery of galaxy clusters and in filaments connecting cosmic structures carries crucial information on their accretion history and on the feedback and enrichment processes from galaxies. In order to study the details of these processes and the three-dimensional structure of the diffuse baryons in clusters and cosmic filaments we resort to large...
Although they are the building blocks of rocky planets and even life, the major fraction of metals in the Universe is found outside galaxies, within a hot, ionized intergalactic phase. When this plasma is hot and dense enough to glow in X-rays (i.e. pervading galaxy clusters, groups, and surrounding isolated elliptical galaxies), the abundance of key chemical elements can be measured via...
Mergers between galaxy clusters are the most energetic phenomena in the Universe. During these cosmic collisions, turbulence and shocks are generated into the ICM where they are believed to power Mpc-scale diffuse synchrotron sources in form of radio halos and radio relics. Nowadays, studies on non-thermal phenomena in merging galaxy clusters have been limited to a few tens of massive systems...
Abell 3266 is a fascinating merging galaxy cluster system, showing a great deal of substructure. There is a plume of low entropy gas running from the core of the cluster, which may be material stripped from a subcluster (Sauvageot et al. 2005; Finoguenov et al. 2005). eROSITA observed A3266 as a calibration target. The wide field of eROSITA and uniform coverage provide an excellent opportunity...
In a growing number of galaxy clusters diffuse extended radio sources have been found. The radio emission implies the presence of cosmic rays and magnetic fields in the intracluster medium (ICM) on megaparsec scales. An important question is how the cosmic rays are accelerated that produce these extended synchrotron emitting sources. It is generally believed that shocks and turbulence play an...
We present the large-scale multi-wavelength view of the nearby (z~0.05) Abell 3391/95 multiple galaxy cluster system. We have obtained (i) the first deep (~10 ks nominal) large-area (~10 sq.deg) high-quality X-ray data using eROSITA in scan mode during its Performance Verification Phase; (ii) an even larger scale sensitive (~30 uJ) radio continuum image obtained with ASKAP as part of the EMU...
Abell 3391/3395 is a pair of galaxy clusters at z=0.05. The clusters A3391, A3395, and a galaxy group located between the two clusters are in alignment along a large-scale filament. The previous studies by ASCA, ROSAT, Planck, Suzaku, and Chandra indicate and confirm that A3395 and A3391 are connected by the filament with hot diffuse gas. The eROSITA first-light observation of A3391/95 has...
One of the X-ray brightest clusters – A1656 (Coma) – was observed during the PV program for 2 days covering the cluster up to its virial radius and beyond. We will present the results of imaging and spectral analysis of these data and immediate implication for the cluster studies with SRG/eROSITA.
The thermal and kinematic SZ effects provide a strong and independent complement to X-ray observations of the warm and hot ionised intracluster and intergalactic media, particularly at high redshift where X-ray counts are limited. Being observable from the ground, new instrumentation for the SZ effects can be developed more rapidly and can be upgraded more readily. I will discuss a newly...
Previous X-ray studies of the Perseus Cluster, consisting of 85 Suzaku pointings along eight azimuthal directions, revealed a particularly steep decrease in the deprojected temperature profile near the virial radius r_{200} along the northwest (NW). We have investigated four additional Suzaku observations mapping this region, with a total exposure of ~100 ks. With this deeper data set,...
In this talk (could also be a poster) I will present a model of how active galactic nuclei populate the cosmic web (detailed in Comparat et al. 2019).
Then I will show preliminary results on the observed angular clustering of point sources in the eROSITA eFEDs PV observations.
The first large area survey of eROSITA unveiled a small set of Active Galactic Nuclei with unusually steep and flat spectral slopes. In the calibration period and the all-sky survey eROSITA also revisited well-known X-ray sources. We report on an automated detection of spectral changes in the X-ray sky compared to archival observations, based on the XMM-Newton, Chandra and Swift archives. The...
One of the most prominent AGNs, the ultrasoft Narrow-Line Seyfert 1 Galaxy 1H0707-495, has been observed with eROSITA as one of the first CAL/PV observations on October 13, 2019 for about 60.000 seconds. 1H 0707-495 is a highly variable AGN, with a complex, steep X-ray spectrum, which has been the subject of intense study with XMM-Newton in the past. 1H0707-495 entered an historical low hard...
Determining which conditions within galaxies enhance or reduce central SMBH growth is challenging. AGN variability can wash out underlying correlations between galaxy and AGN properties, while AGN selection biases further complicate the observational picture. I will present recent work that addresses these issues, using deep Chandra X-ray data and stellar mass-selected galaxy samples to...
State-of-the-art cosmological simulations of galaxies and galaxy clusters, such as IllustrisTNG (www.tng-project.org), suggest a scenario whereby the quenching of star formation in massive galaxies is caused by gas removal from the central regions of galaxies, in addition to gas heating, because of the activity of super massive black holes. The IllustrisTNG project comprises a series of...
The growth history of supermassive black holes is known to be influenced by their environment from the host galaxy to larger scale structure. However, the direct physical mechanisms involved are not fully understood. The wide imaging, depth, and superb spatial resolution of the Subaru Hyper-Suprime Cam Strategic Survey Program provides the opportunity to make significant progress. For...
Outflowing winds are now revealed routinely in Active Galactic Nuclei and Quasars across the entire electromagnetic spectrum and are invoked in many co-evolutionary models to link the growth of SMBH and galaxies through feedback phenomena. Both numerical simulations and observations have shown that the nature of AGN outflows is multiphase, and that each gas phase embeds a fundamental piece of...
We present physical properties (e.g., X-ray luminosity and hardness ratio) of WISE 22 $\mu$m-selected galaxies/AGNs. Using a latest eFEDS X-ray point source catalog with optical and mid-infrared (IR) counterparts, we made a sub-sample of 2102 objects with S/N (22 $\mu$m) > 5.0. After removing possible stars, we cross-identified with KiDS, VIKING (near-IR), and H-ATLAS (far-IR) catalogs, which...
In order to answer some of the major open questions in the fields of supermassive black hole (SMBH) and galaxy evolution, a complete census of SMBH growth, i.e., active galactic nuclei (AGN), is required. Thanks to the combination of the new deep all-sky surveys, such as those by the Wide-field Infrared Survey Explorer (WISE) and the Spectrum-Roentgen-Gamma (SRG) missions eROSITA and ART-XC,...
Surveys of the extragalactic Universe, from ultraviolet to infrared
wavelengths, have been extremely effective at piecing together a basic picture
of how stars in galaxies evolved throughout cosmic history. At X-ray
wavelengths, normal-galaxy emission (i.e., not due to AGN) is dominated by hot
gas and populations of X-ray binaries (XRBs). eROSITA is expected to detect
~10,000 normal galaxies...
Since its launch in 2012, NuSTAR, as the first imaging X-ray observatory to operate in the 3-80 keV band, has executed an observing program on normal and starburst galaxies, including several galaxies in the Local Group, through a combination of science team, Legacy project, and Guest Observer time. We report on recent results from a synthesis analysis of a dozen galaxies observed by NuSTAR,...
We present an analysis of the X-ray properties of all galaxies within a radius of 200 Mpc observed with XMM-Newton. These galaxies are the result of cross-correlation between the XMM-Newton archive and the HECATE catalogue, the most complete galaxy catalogue of the local Universe incorporating robust distances and stellar population parameters. In our analysis we use data from all objects...
Low mass, low metallicity starburst galaxies are of special interest for galaxy evolution, since they are not only laboratories for massive star evolution and feedback at low metallicity, but also the extreme end of energy input into a galacitic potential. In many ways they are the best proxies for the z ~ 6 to 10 protogalaxies, which are inaccessible to detailed observational studies.
The...
High mass X-ray binaries (HMXBs) offer a unique opportunity to study the physics of accretion in extreme environments and magnetic fields. In these systems, matter is accreted from a massive star onto a compact object which is usually a neutron star. A large number of HMXBs is found in the Magellanic Clouds, especially in the Small Magellanic Cloud (SMC). This is attributed to their ideal...
We will present diffuse X-ray background maps obtained with Solid-state Slit Camera (SSC) on board the MAXI mission for 2 years from 2009 to 2011, in energy bands of 0.7-1.0, 1.0-2.0, and 2.0-4.0 keV (arXiv:1912.01572). They are the first ones that were derived with a solid-state instrument, and to be compared with the previous ROSAT all sky survey result. While the SSC map in the highest...
eROSITA is poised to unleash a deluge of information on the stellar X-ray sky in a nexus with other powerful complementary missions and capabilities, such as TESS, Gaia and LSST. I will endeavour to provide a brief overview of the outstanding problems in high energy stellar physics, and the status of our knowledge deep into the Chandra and XMM-Newton era. I will describe some important aspects...
Ultracool dwarfs (UCDs) are objects with spectral type M7 and later, at the age-dependent transition between stellar and brown dwarf regime. In the predominantly neutral photospheres of UCDs the magnetic field and the matter are expected to show poor coupling, and this should be shutting off the magnetic activity. Nevertheless, radio, Halpha and X-ray emission has occasionally been observed...
We have developed a fully Bayesian scheme to statistically
extract the full stellar source content in the eROSITA all-sky survey.
The identification scheme heavily relies on Gaia data, since
all coronal X-ray sources should have a Gaia counterpart with
significant parallax, and assigns to every X-ray source
a probability with which a given X-ray source is stellar. With
our chosen priors the...
The eta Chamaeleontis cluster is a nearby, moderately dispersed star forming region at an intermediate age of 5-10 Myr. Its members are prime targets to study pre-main sequence evolutionary models, accretion properties, disc dispersal and planet formation and are repeatedly observed by major ground and space based facilities. The cluster has been observed by eROSITA in mid November 2019 in the...
Massive stars of basically all spectral types emit X-rays. Despite tremendous efforts undertaken in the last 20 years, the exact physical mechanisms responsible for their X-ray emission are still not fully understood. The eROSITA survey will deliver a clear X-ray view of massive stars within 2 kpc from the sun. eROSITA's sensitivity in the hard band will become a key diagnostic tool to detect...
Modern X-ray telescopes have revealed the exquisite detail and complexity of supernova remnants (SNRs) at high energies. The metals synthesized in explosions are X-ray bright for many thousands of years, and Chandra, XMM-Newton, Suzaku, and NuSTAR have offered an up-close view of the nucleosynthetic products and their dispersal into the interstellar medium (ISM). In this talk, I will review...
The interstellar medium (ISM) is heated and ionized by radiation, by stellar winds, and finally, by supernova explosions of massive stars. Since these processes are often correlated in space and time, they can form large interstellar structures called superbubbles, which are filled with hot thin plasma. Supernova remnants and superbubbles can be studied best in soft X-ray line and continuum...
Supernova remnants are prominent candidates for the acceleration of the Galactic cosmic rays. SNRs are well-known sources of thermal X-ray emission originated from the shock-heated gas and non-thermal (synchrotron) emission caused by very high-energy electrons moving in the magnetic fields. Non-thermal X-ray synchrotron emission provides important information about particle acceleration...
We will present a full-color X-ray view of the radio nebula W50 which harbors the remarkable Galactic microquasar SS 433 provided by SRG/eROSITA. This system is a unique showcase of the impact that sources with hyper Eddington accretion rates might have on their environments, featuring jets, shocks, particle acceleration to Very High Energies and more. An unprecedentedly sensitive and complete...
Black hole X-ray binaries represent one of the few means available for probing the supernova process, and one of the most useful means for understanding binary evolution under extreme conditions. At the present time, nearly all known black hole X-ray binaries have been selected due to luminous outbursts from their accretion disks. With eROSITA's imaging survey, it will be possible to build...
In high mass X-ray binaries (HMXBs), the black hole or neutron star accretes matter from the wind of a massive supergiant companion: the stellar wind drives changes in the accretion and thus the system’s X-ray emission. But the interaction of this emission with the wind material can also be used to study the wind itself, in particular its geometry, porosity (or clumpiness), mass-loss rate and...
We report on preliminary results of simultaneous eROSITA and XMM-Newton observations of the isolated neutron star PSR B0656$+$14. Data were obtained for almost 100 ks with eROSITA and 70 ks with XMM-Newton under excellent space weather conditions. The target was chosen to investigate a weak absorption feature between 0.5 and 0.6 keV that was tentatively identified in previous deep XMM-Newton...
Double degenerate white dwarf binaries result from episodes of common envelope evolution and evolve to short orbital period through gravitational wave emission. When the lighter of the two white dwarfs fills its Roche Lobe, mass transfer is initiated onto the heavier white dwarf, resulting in X-ray emission. At sufficiently close separation, the transferred mass does not form an accretion...
During first months of the SRG operation the ART-XC telescope (working energy range 4-30 keV) performed observations in different modes: scanning observations of a number of sky fields, pointing observations and all-sky survey. These observations allowed us to discover new transient sources with different observational properties. In particular, the typical time variability of new sources is...
We employ a binary population synthesis, combined with a detailed treatment of mass transfer onto neutron stars and black holes from the optical component with the help of the MESA stellar evolution code, to model populations of binary X-ray sources in galaxies. Wind-fed accreting neutron stars are calculated with taking into account different regimes of quasi-spherical accretion onto...
In August-September 2019, the ART-XC telescope scanned a large field (about 40 sq. deg) around the Galactic Center for nearly 3 weeks as part of the SRG Cal-PV phase. This resulted in a unique survey of the Galactic Bulge in the hard X-ray band of 4-30 keV. The main results of this survey will be presented, with a focus on the statistical properties of cataclysmic variables and low-luminosity...
We present results of the survey of two regions of the Galactic Plane (Norma
arm and the region around galactic longitude l=+20 deg), obtained with the ART-XC telescope
on board the SRG observatory in hard X-rays during the Cal-PV phase. The
total area covered by this survey was about 50 sq.degrees with the median
exposures of ~700 s in the l+20 field and ~1.4 ks in the Norma arm field,...
We will present the first results of a deep raster-scan
observation of the Galactic plane field, carried out by the
SRG/eROSITA telescope as a part of its CalPV program.
The field is centered at Galactic longitude l=20 degrees and covers a
total area of 25 sq. deg with a mean exposure of 8 ksec. We have
detected more than 2000 individual point X-ray sources,
demonstrating a wide variety of...
Low-mass X-ray binaries can lay dormant, remaining undetected for decades, until they are usually detected by X-ray monitoring satellites when they undergo bright outbursts. However, during these periods of quiescence between outbursts, low level accretion does occur but usually cannot be studied at X-ray energies due to their extremely low fluxes. We have been monitoring ~40-50 X-ray binaries...
The eROSITA instrument onboard the SRG satellite provides a unique opportunity
for discovering transients in its X-ray All Sky survey data. There are many
classes of transients known to emit in X-rays, ranging from flares from active
stars to fast blazar variability. By necessity, I will highlight a few such
source classes and the open science questions that will benefit tremdously from
the...
The study of massive stars exploding as supernovae has seen a major breakthrough in recent years, with modern surveys making the detection and exploration of supernova explosions within a day of stellar core collapse possible. With its extremely wide field of view and mature infrastructure of integrated hardware, software and operations, the Zwicky Transient Facility (ZTF) has made such...
X-ray observations of Tidal Disruptions Events (TDEs) are a unique probe of the physics of accretion around supermassive black holes, as they are thought to transition from super- to sub-Eddington accretion on timescales of months/years. The first TDE candidates were found in the X-rays with the ROSAT All-Sky Survey, but, today, most of our candidates are found in the optical. While optical...
Due to eROSITA’s cadence and its 30-fold increased sensitivity in the soft X-ray band relative to ROSAT, eROSITA promises to detect 1000s of tidal disruption event (TDE) candidates during its all sky survey phase. I will present our machine-learning assisted approach for identifying TDE candidates amongst the millions of X-ray sources in eROSITA's source catalogues, and selected early results...
Almost 200 changing-look AGN/quasars are currently known showing significant spectroscopic and photometric variability on timescales of months to years. Although initially discovered by serendipity, systematic searches of archival survey data, such as SDSS, Pan-STARRS, and CRTS, have identified such sources in significant numbers. Ongoing time domain sky surveys, such as ZTF, which cover the...
During its PV phase eROSITA observed a ~100 deg2 field to the final depth expected after eight all-sky scans. The XMM Atlas survey is covered in this field. Between these data sets, we search for dramatic flux changes in AGN which would indicate AGN ignition/shut-down. I will present a few candidate events. We will extend this work using the data of all individual eight all-sky surveys by...
The Zwicky Transient Facility (ZTF) started science operation in March 2018. 40% of ZTF observing time is dedicated to two public surveys: one covering the entire Northern sky every three nights in g and r passbands and one visiting the Galactic Plane every night in g and r. In addition to the public Galactic Plane survey, ZTF has conducted a dedicated high-cadence survey of selected Galactic...
Ultraluminous X-ray sources are powerful extra-nuclear sources of X-rays found in nearby galaxies, which in most cases are believed to be powered by super-Eddington accretion onto neutron stars and black holes. While most known ULXs are persistent sources, recently some new sources have been found that appear to come and go. I will present results from a systematic search for these transient...
XMM-Newton supports currently nine joint programs and observes about 30% of its high priority targets simultaneously with other facilities. In addition, the observing program shows and exceptional high amount of TOO observations in comparison to other large observatory class mission. The talk describes the policy for joint programs and TOO and reflects on the potential for synergies with eROSITA.
A large number of transient low mass X-ray binaries (LMXB) exhibit a knee in the decay stage of their light curves where the X-ray flux transits from a slow-decay stage to a rapid-decay stage. For the case of neutron stars, it had long been suggested that this sharp drop in the luminosity is due to transition from accretion to the propeller stage i.e.\ formation of a centrifugal barrier at low...
We present results of cosmological redshift measurements for X-ray AGNs discovered by eRosita in the Lockman Hole extragalactic field during the SRG PV-phase survey. Photometric redshifts and related classification (absorbed/unobsorbed AGN) of X-ray sources were performed by machine learning photo-z models implemented in SRGz package. We discuss the importance of different photometric data...
Elliptical galaxies, especially those lacking an actively accreting supermassive black hole dominating the X-ray emission, tend to be located outside our immediate local neighbourhood, and should present an area of significant gain by the eROSITA survey. We highlight some of the science that is feasible with detailed studies of early-type galaxies via presentation of preliminary results from...
Galaxy clusters are the most massive gravitationally bound objects in the universe, forming the nodes of the cosmic web. The imprint of structure formation is carried by the galaxy cluster number density and spatial distributions of galaxy clusters. Hence, these cluster properties are sensitive to the underlying cosmological model. Specifically, the abundance of galaxy clusters with mass and...
In classical supergiant X-ray binaries (SgXBs), the Bondi-Hoyle-Lyttleton wind accretion was usually assumed which caused negligible changes in angular momentum of accretors. The observed spin-up of the neutron star, however, is still a hanging problem. In this paper, we report an extended low state of Vela X-1 (at about orbital phases 0.16—0.2), lasting for at least 30 ks, observed with...
In this study we present linear and circular polarisation maps in the optical rangeof the core and the jet in M87. The observations were acquired two days before theEvent Horizon Telescope campaign in early April 2017. A high degree (∼18%) of linearpolarisation is detected in three knots resolved along the jet from∼10′′up to23′′(0.8–1.8 kpc) from the centre, while the nucleus and...
Studies of the cosmological backgrounds are approaching the very technological limits of our present day instrumentation capabilities. But already today the systematic uncertainties exceed the statiscal ones. Simply, because our actual knowledge of the Milky Way foregrounds is not sufficient. We need to quantify precisely the essential quantity, the density distribution of hydrogen nucleons...
The study of the brightest cluster galaxy (BCG) coronae of noncool core (NCC) galaxy clusters and their central active galactic nuclei (AGN) is crucial for understanding the BCG's role on galaxy cluster evolution, as well as the activation of the self-regulated cooling and heating mechanism in the central regions of galaxy clusters. In this talk, I will present the X-ray properties of the...
Active galactic nuclei (AGN) are known to be variable in many respects and across many timescales. In order to probe the geometry of AGN and better understand their overall variability it is important to disentangle spectral components corresponding to the different structures surrounding the central supermassive black hole (SMBH). In the X-ray band, the main contributors to spectral...
Theory predicts that an accreting supermassive black hole binary (SMBHB) could be observed as an active galactic nucleus (AGN) that periodically varies in luminosity on the order of its orbital timescale, due to mechanisms such as binary-modulated accretion and relativistic Doppler boost. Several studies have searched for periodically varying quasars as possible SMBHBs in optical time domain...
It is now firmly established that remnant planetary systems orbit and pollute the surfaces of white dwarf stars with heavy elements, providing a unique empirical tool to assess the bulk composition of extrasolar planetary bodies. Yet despite the existence of myriad stars polluted by up to 15 heavy elements, and (self-consistent) model inferences for their mass accretion rates, there remains no...
The well studied Narrow-Line Seyfert 1 galaxy 1H0707-495 has been
observed by eROSITA for the first time in October 2019 simultaneously
with XMM-Newton. Besides its strong variability, it is most famous for
its steep spectral drop at 7 keV. Complementary to the contribution by
T. Boller et al., we will present a detailed spectral analysis of this
joint observation of 1H0707-495 in this...
The North Ecliptic Pole region is a subject of deepest surveys with many space bourne observatories, including the infrared observatory AKARI and Spectrum-RG. In particular, as a legacy program of AKARI, it pursued dedicated AKARI NEP Deep (ANEPD;~0.5 deg$^2$) and Wide (ANEPW;~5.4 deg$^2$) surveys in the NEP area with its unique nine infrared bands continuously covering the wavelength range...
The isotropy of the late Universe and consequently of the X-ray galaxy cluster scaling relations is an assumption greatly used in astronomy. However, many studies have recently reported deviations from isotropy using various cosmological probes, with a definitive conclusion yet to be made. New, effective and independent methods to robustly test the cosmic isotropy are of crucial importance. We...
We summarize the eROSITA in-flight calibration plan, from its design
phase to versions with selected celestial targets
optimized for various launch dates, to planning , implentation and
execution, and finally to the data analysis and the anticipated
calibration parameters.
It is known that the fraction of blue galaxies in galaxy clusters increases with increasing redshift, suggesting that star formation in the galaxy clusters has decayed rapidly over cosmic time (Butcher & Oemler 1984). Nearby groups of galaxies often show the anti-correlation between the blue fraction of member galaxies and their X-ray luminosities (Mulchaey 2003; Ota et al. 2004). However,...
In this talk, I will discuss our current understanding of the formation efficiency of high-mass X-ray binaries (HMXBs) by focusing on results derived from young accreting binary populations in the Magellanic Clouds. Using data from our Chandra X-ray Visionary program, extensive shallow Chandra and XMM-Newton surveys and the literature for the Small and Large Magellanic Cloud (SMC and...
