SRG/eROSITA-triggered XMM-Newton observations of three Be/X-ray binaries in the LMC: Discovery of X-ray pulsations
F. Haberl, C. Maitra, D. Kaltenbrunner, D. A. H. Buckley, I. M. Monageng, A. Udalski, V. Doroshenko, L. Ducci, I. Kreykenbohm, P. Maggi, A. Rau, G. Vasilopoulos, P. Weber, J. Wilms
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Accepted for publication in Astronomy & Astrophysics
Using data from eROSITA, the soft X-ray instrument aboard Spectrum-Roentgen-Gamma (SRG), we report the discovery of two new hard transients, eRASSU J050810.4-660653 and eRASSt J044811.1-691318, in the Large Magellanic Cloud. We also report the detection of the Be/X-ray binary RX J0501.6-7034 in a bright state. We initiated follow-up observations to investigate the nature of the new transients and to search for X-ray pulsations coming from RX J0501.6-7034. We analysed the X-ray spectra and light curves from our XMM-Newton observations, obtained optical spectra using the South African Large Telescope to look for Balmer emission lines and utilised the archival data from the Optical Gravitational Lensing Experiment (OGLE) for the long-term monitoring of the optical counterparts. We find X-ray pulsations for eRASSU J050810.4-660653, RX J0501.6-7034, and eRASSt J044811.1-691318 of 40.6 s, 17.3 s, and 784 s, respectively. The Halpha emission lines with equivalent widths of -10.4 A (eRASSU J050810.4-660653) and -43.9 A (eRASSt J044811.1-691318) were measured, characteristic for a circumstellar disc around Be stars. The OGLE I- and V-band light curves of all three systems exhibit strong variability. A regular pattern of deep dips in the light curves of RX J0501.6-7034 suggests an orbital period of ~451 days. We identify the two new hard eROSITA transients eRASSU J050810.4-660653 and eRASSt J044811.1-691318 and the known Be/X-ray binary RX J0501.6-7034 as Be/X-ray binary pulsars.
We present a probabilistic model built for the optical cross-match between the SRG/eROSITA X-ray sources and photometric data from the DESI Legacy Imaging Surveys. The model relies both on positional and photometric information on optical objects nearby X-ray sources and allows performing selection with precision and recall $\approx94$% (for $F_{\rm X,0.5-2}>10^{-14}$ erg/s/cm$^2$). With this model, we calibrated positional error of the SRG/eROSITA sources detected in the Lockman Hole: $σ_{\rm corr} = 0.87\sqrt{ σ_{\rm det}^{2.53} + 1.12^2}$. The model will become a part of the SRGz system for…
We present the results of the optical identification, classification, as well as analysis of photometric and spectral observations of the X-ray transient SRGe2149+6736 detected by the eROSITA telescope during SRG all-sky X-ray survey. Photometric observations of the optical companion of SRGe2149+6736 were carried out on 6m telescope BTA SAO RAS, 1.5m Russian-Turkish telescope RTT-150 and 2.5m telescope CMO of Moscow State University. Together with ZTF data they showed that the source is a cataclysmic variable with an orbital period $P=85\pm0.4$~min which demonstrates long-term brightness varia…
X-ray emission from counterparts of historical classical novae (CNe) in our Galaxy is studied. To this end, we use data from three SRG/eROSITA sky surveys in the hemisphere analyzed by the RU eROSITA consortium. Out of 309 historical CNe, X-ray emission has been detected from 52 sources with 0.3-2.3 keV luminosities in the $\rm L_X\approx 10^{30}\sim 10^{34}$ erg/s range. Among them, two sources have supersoft spectra and are associated with the post-nova supersoft X-ray emission. Hardness of X-ray spectra of some of the remaining sources tentatively suggests that magnetized white dwarfs (WDs)…
A four-year sky survey with the use of the eROSITA telescope on board the Spektr-RG observatory will provide the best coverage in the soft (0.5-2 keV) and standard (2-10 keV) X-ray ranges, both in terms of sensitivity and angular resolution. We have analysed the possibility of detecting various types of isolated neutron stars with eROSITA. Among already known objects, eROSITA will be able to detect more than 160 pulsars, 21 magnetars, 7 central compact objects, all seven sources of the Magnificent Seven, and two other X-ray isolated neutron stars during the four-year survey mission.
We present a method for the optical identification of sources detected in wide-field X-ray sky surveys. We have constructed and trained a neural network model to characterise the photometric attributes of the populations of optical counterparts of X-ray sources and optical field objects. The photometric information processing result is used for the probabilistic cross-match of X-ray sources with optical DESI Legacy Imaging Surveys sources. The efficiency of the method is illustrated using the SRG/eROSITA Survey of Lockman Hole. To estimate the accuracy of the method, we have produced a validat…
We report the discovery of three previously unknown cataclysmic variables in the data of the first year of the all-sky X-ray survey by the SRG orbital observatory. The sources were selected due to their brightness in the 4--12 keV band in the data of the Mikhail Pavlinsky ART-XC telescope. They are also detected by the eROSITA telescope, which provided accurate localizations and spectral data for broad-band spectral analysis. All three objects had been previously known as X-ray sources from the ROSAT all-sky survey and XMM-Newton slew survey, but their nature remained unknown. The X-ray spectr…
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) instrument onboard the Russian-German `Spectrum-Roentgen-Gamma' (SRG) mission observed the Her X-1/HZ Her binary system in multiple scans over the source during the first and second SRG all-sky surveys. Both observations occurred during a low state of the X-ray source when the outer parts of the accretion disk blocked the neutron star from view. The orbital modulation of the X-ray flux was detected during the low states. We argue that the detected X-ray radiation results from scattering of the emission of the central source by …
In this note we discuss the possibility of detecting the accompanying X-ray emission from sources of fast radio bursts with the eROSITA telescope onboard the Spektr-RG observatory. It is shown that during four years of the survey program about 300 bursts are expected to appear in the field of view of eROSITA. About 1\% of them will be detected by ground-based radio telescopes. For a total energy release $\sim~10^{46}$~ergs depending on the spectral parameters and absorption in the interstellar and intergalactic media, an X-ray flare can be detected from distances from $\sim 1$~Mpc (thermal spe…
We discuss the potential of the eROSITA telescope on board the \emph{Spectrum-X-Gamma} observatory to detect gamma-ray burst (GRB) X-ray afterglows during its 4-year all-sky survey. The expected rate of afterglows associated with long-duration GRBs without any information on the bursts proper that can be identified by a characteristic power-law light curve in the eROSITA data is 4--8 events per year. An additional small number, $\lesssim 2$ per year, of afterglows may be associated with short GRBs, ultra hard (GeV) GRBs and X-ray flashes. eROSITA can thus provide the first unbiased (unaffected…
We report the discovery of X-ray emission from CFHQS J142952+544717, the most distant known radio-loud quasar at z=6.18, on Dec. 10--11, 2019 with the eROSITA telescope on board the SRG satellite during its ongoing all-sky survey. The object was identified by cross-matching an intermediate SRG/eROSITA source catalog with the Pan-STARRS1 distant quasar sample at 5.6 < z < 6.7. The measured flux $\sim 8 \times 10^{-14}$ erg cm$^{-2}$ s$^{-1}$ in the 0.3--2 keV energy band corresponds to an X-ray luminosity of $2.6^{+1.7}_{-1.0}\times 10^{46}$ erg s$^{-1}$ in the 2--10 keV rest-frame energy band,…
We report the results of follow-up investigations of a possible new thermally emitting isolated neutron star (INS), 4XMM J022141.5-735632, using observations from XMM-Newton and Spectrum Roentgen Gamma (SRG) eROSITA. The analysis is complemented by Legacy Survey imaging in the optical and near-infrared wavelengths. The X-ray source, the first to be targeted by XMM-Newton in an effort to identify new INS candidates from the fourth generation of the XMM-Newton serendipitous source catalogue Data Release 9 (4XMM-DR9), shows a remarkably soft energy distribution and a lack of catalogued counterpar…
(abridged version) We present a detailed spectroscopic and timing analysis of X-ray observations of the bright radio-to-gamma-ray emitting pulsar PSR B0656+14, which were obtained simultaneously with eROSITA and XMM-Newton during the Calibration and Performance Verification phase of the Spektrum-Roentgen-Gamma mission (SRG) for 100 ks. Using XMM-Newton and NICER we firstly established an X-ray ephemeris for the time interval 2015 to 2020, which connects all X-ray observations in this period without cycle count alias and phase shifts. The mean eROSITA spectrum clearly reveals an absorption feat…
We report the discovery of a giant dust scattering ring around the Black Hole transient MAXI J1348-630 with SRG/eROSITA during its first X-ray all-sky survey. During the discovery observation in February 2020 the ring had an outer diameter of 1.3 deg, growing to 1.6 deg by the time of the second all sky survey scan in August 2020. This makes the new dust ring the by far largest X-ray scattering ring observed so far. Dust scattering halos, in particular the rings found around transient sources, offer the possibility of precise distance measurements towards the original X-ray sources. We combine…
We discuss the potential of the eROSITA telescope on board the Spectrum-Roentgen-Gamma (SRG) observatory to detect stellar tidal disruption events (TDE) during its 4-year all-sky survey. These events are expected to reveal themselves as luminous flares of UV/soft X-ray emission associated with the centres of previously non-active galaxies and fading by few orders of magnitude on time-scales of several months to years. Given that eROSITA will complete an all-sky survey every 6 months and a total of 8 such scans will be performed over the course of the mission, we propose to distinguish TDEs fro…
We report the discovery of a candidate X-ray supernova remnant SRGe J003602.3+605421=G121.1-1.9 in the course of \textit{SRG}/eROSITA all-sky survey. The object is located at (l,b)=(121.1$^\circ$,-1.9$^\circ$), is $\approx36$ arcmin in angular size and has a nearly circular shape. Clear variations in spectral shape of the X-ray emission across the object are detected, with the emission from the inner (within 9') and outer (9'-18') parts dominated by iron and oxygen/neon lines, respectively. The non-equilibrium plasma emission model is capable of describing the spectrum of the outer part with t…
Based on a comparison of the SRG/eROSITA catalog of X-ray active stars and the Gaia catalog, a sample of 502 peculiar objects was obtained for which Gaia, on one hand, detects statistically significant values of parallax or proper motion and, on the other hand, registers signs of the non zero source extent in the optical band. In the log ($F_X/F_{\rm opt}$) - (G-RP) color diagram these objects are separated from the balk of X-ray active stars and are located in the region typical for the galaxies with active nuclei. According to the SIMBAD database, about $\sim 50$% of them are confirmed AGNs …
eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian Spektrum-Roentgen-Gamma (SRG) mission which is scheduled for launch in late 2012. eROSITA is fully approved and funded by the German Space Agency DLR and the Max-Planck-Society.The design driving science is the detection of 50-100 thousands Clusters of Galaxies up to redshift z~1.3 in order to study the large scale structure in the Universe and test cosmological models, especially Dark Energy. This will be accomplished by an all-sky survey lasting for four years plus a phase of pointed obse…
X-ray surveys are well suited to detect, identify and study young stars based on their high levels of magnetic activity and thus X-ray brightness. The eROSITA instrument onboard the Spectrum-Roentgen-Gamma (SRG) satellite will perform an X-ray all-sky survey that surpasses existing data by a sensitivity increase of more than an order of magnitude. The 4 yr survey is expected to detect more than half a million stars and stellar systems in X-rays.
Abstract abridged. The eROSITA X-ray telescope aboard the SRG orbital observatory, in the course of its all-sky survey, is expected to detect about three million active galactic nuclei (AGN) and hundred thousand clusters and groups of galaxies. Such a sample complemented with redshift information, will open a new window into the studies of the Large-Scale structure (LSS) of the Universe and the determination of its cosmological parameters. The purpose of this work is to assess the prospects of cosmological measurements with the eROSITA sample of AGN and clusters of galaxies. We assume the avai…
X-ray panorama of the SS433/W50 complex by SRG/eROSITA
Space Research Institute (IKI)（空间研究所）；Max Planck Institute for Astrophysics（马克斯·普朗克天体物理学研究所）；Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München（慕尼黑大学物理学院大学天文台）
First X-ray detection of symbiotic nova CN Cha with eROSITA/SRG
Dr. Karl Remeis-Sternwarte, Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg（弗里德里希·亚历山大大学埃尔朗根天体粒子物理中心）；Astronomical Institute of Charles University（查理大学天文研究所）；Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）；Institut für Astronomie und Astrophysik, Universität Tübingen（蒂宾根大学天文与天体物理研究所）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）
SN 1987A is the closest observed supernova in the last four centuries and provides a unique opportunity to witness the birth and evolution of a supernova remnant. The source has been monitored by XMM Newton EPIC-pn from 2007--2020. SRG/eROSITA also observed the source during its commissioning phase and the first light in Sept. and Oct. 2019. We investigated the spectral and flux evolution of SN 1987A in X-rays over the last fourteen years up to Nov. 2020 using XMM-Newton and eROSITA observations. We performed a detailed spectral analysis using a three-component plane-parallel shock model and a…
Bayesian Multi-wavelength Imaging of the LMC SN1987A with SRG/eROSITA
Max Planck Institute for Astrophysics（马克斯·普朗克天体物理研究所）；Ludwig-Maximilians-Universität München（慕尼黑路德维希-马克西米利安大学）；Kavli Institute for Particle Astrophysics & Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理学与宇宙学研究所）；Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理学研究所）；Excellence Cluster ORIGINS（ORIGINS卓越集群）
The SRG/eROSITA all-sky survey: Hard X-ray selected Active Galactic Nuclei
Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Department of Astronomy, University of Geneva（日内瓦大学天文学系）；Exzellenzcluster ORIGINS（ORIGINS卓越集群）；Max-Planck Institut für Astronomie（马克斯·普朗克天体物理学研究所）
The supernova remnant (SNR) candidate G 116.6-26.1 is one of the few high Galactic latitude ($|b| > 15^o$) remnants detected so far in several wavebands. It was discovered recently in the SRG/eROSITA all-sky X-ray survey and displays also a low-frequency weak radio signature. In this study, we report the first optical detection of G 116.6-26.1 through deep, wide-field and higher resolution narrowband imaging in $\rm Hα$, [S II] and [O III] light. The object exhibits two major and distinct filamentary emission structures in a partial shell-like formation. The optical filaments are found in exce…
We report a discovery of a new X-ray-selected supernova remnant (SNR) candidate SRGe~J0023+3625 = G116.6-26.1 found in the SRG/eROSITA all-sky survey. The source features a large angular extent ($\sim 4$ deg in diameter), nearly circular shape and X-ray spectrum dominated by emission lines of helium- and hydrogen-like oxygen. It lacks bright counterparts of similar extent at other wavelengths which could be unequivocally associated with it. Given the relatively high Galactic latitude of the source, $b\approx-26$ deg, we interpret these observational properties as an indication of the off-disk …
X-ray reflection off dense molecular clouds in the Galactic Centre region has established itself as a powerful probe for the past activity record of the supermassive black hole Sgr A* on a timescale of a few hundred years. Detailed studies of the reflection signal from individual clouds allow us to estimate parameters of the brightest flare(s) and explore properties of the dense gas distribution inside and around them. On the other hand, wide area surveys covering the full Central Molecular Zone (CMZ) are crucial to spot brightening of the new clouds and long-term decay of the flux from the on…
Context. The Small Magellanic Cloud (SMC) hosts many known high-mass X-ray binaries (HMXBs), and all but one (SMC X-1) have a Be companion star. Through the calibration and verification phase of eROSITA on board the Spektrum-Roentgen-Gamma (SRG) spacecraft, the Be/X-ray binary XMMU J010429.4-723136 was in the field of view during observations of the supernova remnant, 1E0102.2-7219, used as a calibration standard. Aims. We report timing and spectral analyses of XMMU J010429.4-723136 based on three eROSITA observations of the field, two of which were performed on 2019 November 7-9, with the thi…
The nearby young open cluster eta Chamaeleontis has been observed by eROSITA/SRG during its CalPV phase for 150 ks. The eROSITA data were taken in the field-scan mode, an observing mode of Spectrum-Roentgen-Gamma (SRG) that follows a rectangular grid-like pattern, here covering a 5x5 deg field with an exposure depth of about 5 ks. We study the known members in X-rays and search for potential new members of the anticipated dispersed low-mass cluster population. Detected sources were identified by cross-matching X-ray sources with Gaia and 2MASS, and young stars were identified by their X-ray ac…
Magnetic CVs are luminous Galactic X-ray sources but have been difficult to find in purely optical surveys due to their lack of outburst behavior. The eROSITA telescope aboard the Spektr-RG (SRG) mission is conducting an all-sky X-ray survey and recently released the public eROSITA Final Equatorial Depth Survey (eFEDS) catalog. We crossmatched the eFEDS catalog with photometry from the Zwicky Transient Facility (ZTF) and discovered two new magnetic cataclysmic variables (CVs). We obtained high-cadence optical photometry and phase-resolved spectroscopy for each magnetic CV candidate and found t…
We present the results of our identification of 17 X-ray sources detected in the 4-12 keV energy range by the Mikhail Pavlinsky ART-XC telescope during the first year of the SRG all-sky survey. Three of them have been discovered by the ART-XC telescopes, while the remaining ones have already been known previously as X-ray sources, but their nature has remained unknown. We took optical spectra for nine sources located in the northern sky $δ> -20$ deg with the 1.6-m AZT-33IK telescope at the Sayan Observatory (the Institute of Solar-Terrestrial Physics, the Siberian Branch of the Russian Academy…
We present the first sample of tidal disruption events (TDEs) discovered during the SRG all-sky survey. These 13 events were selected among X-ray transients detected in the 0<l<180 deg hemisphere by eROSITA during its second sky survey (10 June - 14 December 2020) and confirmed by optical follow-up observations. The most distant event occurred at z=0.581. One TDE continued to brighten at least 6 months. The X-ray spectra are consistent with nearly critical accretion onto black holes of a few 10^3 to 10^8 M_Sun, although supercritical accretion is possibly taking place. In two TDEs, a spectral …
Context. Puppis A is a medium-age supernova remnant (SNR), which is visible as a very bright extended X-ray source. While numerous studies have investigated individual features of the SNR, at this time, no comprehensive study of the entirety of its X-ray emission exists. Aims. Using field-scan data acquired by the SRG/eROSITA telescope during its calibration and performance verification phase, we aim to investigate the physical conditions of shocked plasma and the distribution of elements throughout Puppis A. Methods. Using broad- and narrow-band imaging, we investigate the large-scale distrib…
