SRG Observatory: Half a Year in Space!

Half a year ago, on July 13, 2019, the SRG astrophysical observatory was launched from the Baikonur Cosmodrome. These six months have been full of events: orbit corrections, switch-on and the “first light” of the ART-XC and eROSITA telescopes, their tuning and calibration, the first scientific observations, entry into the operating orbit around the L2 point, and, finally, the long-awaited beginning of the all-sky X-ray survey.

In the course of the calibration and performance verification phase, during daily communication sessions a total of 360 gigabytes of scientific data were received by three ground stations. The first results of these observations were presented at the all-Russian conference “High-energy astrophysics today and tomorrow – 2019”, which was held in December at the Space Research Institute of the Russian Academy of Sciences in Moscow.

On December 8, 2019, the SRG observatory began its all-sky survey. Completing six revolutions per day around the spacecraft’s axis pointed at the Sun, the telescopes of the observatory will complete the first scan of the whole sky already by June 2020, and a total of 8 such surveys are planned to be carried out over 4 years. The illustration shows (in Galactic coordinates) the one sixth of the sky for which data have been obtained during the first month of the survey. During this period, the ART-XC telescope has detected more than 3 million hard X-ray photons (with energies between 4 and 30 keV) from the distant Universe. It is these photons which are shown on the map.

To demonstrate the huge scientific potential of these data, two small fragments of the map are shown on a much larger scale. In the first of them, one can see an extended object – the hot remnant of the Cassiopeia A supernova, which exploded about 300 years ago in our Galaxy (the colors show the image obtained with ART-XC in hard X-rays, while the contours show for comparison an image obtained previously in soft X-rays with the German ROSAT observatory). In the second field, three point-like sources are clearly visible: two X-ray binary systems,

V395 Car and MAXI J0911-655, in our Galaxy, in which matter from a normal star is flowing onto a neutron star (in the latter case, a strongly magnetized neutron star is spinning 340 times per second), and a Seyfert galaxy, IRAS 09149-6206, at a distance of 840 light-years from us, where accretion of interstellar medium onto a supermassive black hole takes place.

The service systems of the SRG spacecraft and all 14 units of the ART-XC and eROSITA telescopes continue to operate in nominal regime, providing the scientists with new data on a daily basis. The unique all-sky X-ray survey is going on!

 

Spectrum-RG Orbital X-ray Observatory Begins its All-sky Survey

The Spectrum-RG orbital X-ray observatory, launched from the Baikonur kosmodrom on July 13, 2019, begins the survey of the entire sky. On December 8, a spacecraft moving along the orbit around the L2 libration point at a distance of one and a half million kilometers from the Earth, started rotation around the axis directed towards the Earth. Thus, the SRG observatory began scanning the sky along the big circle on the celestial sphere, marking the start of the 4-years long all-sky survey. Following the Earth movement around the Sun, the ART-XC and eRosita telescopes will obtain every six months the map of the whole sky more sensitive than any all-sky data obtained by X-ray astronomers so far. The sum of eight independent sky maps that are expected after four years of the survey will make it possible to achieve record-high sensitivity and find about three million active nuclear galaxies and quasars, hundreds of thousands of clusters and group galaxies, and about half a million active stars, white dwarfs, pulsars and remnants of supernova explosions, neutron stars and black holes in our Galaxy. Comparison of individual sky maps will allow astrophysicists to monitor variability of millions of X-ray sources over the entire sky.

The main scientific goal of sky survey is the study of the large-scale structure of the Universe and the study of the nature of Dark Matter and Dark Energy. At the same time, the unprecedented sensitivity of the survey and numerous selection of X-ray sources of different types that will be discovered during the survey have enormous potential for new discoveries and will gain research in all branches of modern high-energy astrophysics.

The beginning of the sky survey was preceded by the painstaking work of scientists and engineers at the Space Research Institute (IKI) of the Russian Academy of Sciences in Moscow and at the Institute of Extraterrestrial Physics (MPE) of the Max Planck Society in Germany to set up and calibrate two unique X-ray telescopes. This work ended with extensive verification observations, during which the telescopes were tested during real observations of astrophysical objects. The figures below demonstrate the capabilities of the SRG / eRosita telescope for conducting deep sky fields with the size of tens of square degrees (see also the image of the eFEDS mini-survey on the MPE website).

Figure 1 shows an X-ray map of the Galactic disk region (the so-called “Ridge of the Galaxy”) obtained by the eRosita telescope in October 2019. As seen from the image map with a size of 25 squared degrees, numerous X-ray sources were detected, both located in our Galaxy, and quasars located at large distances from the Earth and observed through the Galaxy. Of great interest are Galactic objects: clusters of young stars emitting in X-rays, stars even less massive than our Sun, but having corona emitting in X-rays thousands of times brighter than the corona of our Sun. The map also shows X-ray pulsars: rapidly rotating magnetized neutron stars, the remnants of supernova explosions in which shock waves emit X-ray photons due to collisions of gas detached from a dead star with the surrounding interstellar matter. The map exhibits zones of diffuse X-ray emission. Blue and green colors correspond to high photon energies emitted by a gas with a temperature of tens of millions of degrees, and red color corresponds to a colder gas with a temperature of hundreds of thousands to a million degrees.

The Lockman Hole is a unique area in the sky where the absorption of X-rays by the interstellar medium of our Galaxy reaches its minimum value, which allows us to study distant quasars and clusters of galaxies with record sensitivity. In the sky region with the size of 20 square degrees, the eRosita telescope detected about 6,000 X-ray sources (Figure 2). The vast majority of these sources are the active galactic nuclei and quasars, the radiation of which is associated with the accretion of matter into a supermassive black hole. According to photometric redshift estimate, the most distant of them are located at redshifts up to z ~ 4-5. Also found more than 100 clusters of galaxies and several hundred active stars located in our galaxy.

The images shown above were obtained within the Russian quota of observational time of the eRosita telescope, and were analyzed by the scientists of the high-energy astrophysics department at IKI.

“Spectrum-RG: 100 days in flight” press conference

Link to broadcast: http://pressmia.ru/pressclub/20191022/952527193.html

October 22 at 14:30 MSK at the International Multimedia Press Center of the MIA “Russia Today” will host a multimedia press conference on the topic: “Spectrum-RG: 100 days in flight”.

The participants:
– Scientific leader of the Spectrum-RG project, academician of the RAS Rashid SYUNYAEV;
– Deputy Head of Department – Head of Department of Roscosmos State Corporation Viktor VORON;
– Deputy Head of  NPOL Ilya LOMAKIN;
– Deputy Scientific Director of the Spectrum-RG project, Corresponding Member of the RAS Eugene CHURAZOV;
– Leading Researcher at IKI, Corresponding Member of RAS Marat GILFANOV;
– Principal Investigator of the ART-XC telescope, head of the high-energy astrophysics department at IKI Mikhail PAVLINSKY;
– Head of the Department of Ground-Based Scientific Complexes, IKI RAS Vladimir NAZAROV.

Link: https://ria.ru/20191021/1560017579.html

The first SRG/eROSITA X-ray image

On August 26, 2019 the first X-ray image was obtained by one of the seven eROSITA telescope modules  on board the Spektr-RG space observatory. 

The image of the UDS field with an area of the order of one square degree clearly shows dozens of X-ray sources, mainly active galactic nuclei and quasars. The image was obtained with the exposure of about 2000 seconds in the 0.5–2 keV energy range. Data obtained by Russian and German consortiums of the SRG/eROSITA mission.

The first X-ray image obtained by one of the seven eROSITA telescope modules on board the Spektr-RG space observatory in the 0.5-2 keV energy range. Data obtained by Russian and German consortiums of the SRG/eROSITA mission.

SRG/ART-XC continues to see activity from Sgr A*

ATel #13039M. Pavlinsky on behalf of the ART-XC collaboration (Space Research Institute (IKI), Moscow, Russia)

The ART-XC telescope onboard Spektr-RG space observatory continues to monitor the Galactic center region after reports on Sgr A* flaring activity (ATel #13007, #12768).

Recent ART-XC observations of Sgr A* on August 15-16 (2019-08-14T23:40 – 2019-08-15T14:00 and 2019-08-15T23:40 – 2019-08-16T14:00, UTC) with total exposure of 50 ks each, demonstrate source average 5-16 keV flux at the level of 1.6×10-11 erg cm-2 s-1, which corresponds to the luminosity of 1.4×1035 erg s-1 , assuming a distance of 8.5 kpc. This measurement of the source luminosity is comparable to that observed with ART-XC on August 12 (ATel #13023). We also see a small flux variability at the level of 15% on the timescale of a few hours. More detailed information will be provided in the corresponding publication, which is under preparation.

Multi-wavelength observations are encouraged; next time when ART-XC will observe Sgr A* is between 2019-08-22T05:46 and 2019-08-22T15:20 UTC.

The first scientific publication: SRG/ART-XC observes activity from Sgr A*

The SRG/ART-XC collaboration sent its first astronomic “telegram” on observing the supermassive black hole Sagittarius A* in the center of the Milky Way.

ATel #13023; M. Pavlinsky on behalf of ART-XC collaboration (IKI RAS, Moscow)
on 13 Aug 2019; 21:56 UT

Following the recent report on Sgr A* flaring activity (ATel #13007, #12768) ART-XC telescope onboard Spektr-RG observed the Galactic center region for 50 ks during the period between 2019-08-11 22:27:50 UTC and 2019-08-12 13:19:12 UTC

We found Sgr A* in unusually active state: using absorbed power-law spectral model (slope Γ=2, following Zhang+17) we estimated mean flux in 5-16 keV band as (1.6±0.2)x10-11 erg cm-2 s-1, which corresponds to the unabsorbed bolometric luminosity of 2×1035 erg s-1 (0.1-20 keV), assuming a distance of 8.5 kpc.

We also noticed variability on timescale of few kiloseconds.
Because of preliminary calibration status of ART-XC more accurate details will be provided in the following article.

Multi-wavelength observations are encouraged; ART-XC will observe Sgr A* between 14.08.2019 23:40 and 15.08.2019 15:20 UTC

http://www.astronomerstelegram.org/?read=13023

HEASARC Picture of the week

Seven First Lights of ART-XC

One of the most exciting times in the life of any astronomical observatory is achieving “first light“, the first time a telescope produces an image of an astronomical object. For space-based observatories, this can be a time that’s especially nerve-wracking, given the remote nature of the science and the fact that it can be difficult to address problems in deep space. As capabilities grow, and observatories are placed farther from earth, problems encountered are ever harder to resolve. The Spektr-RG observatory (or SRG as it’s more commonly known) is a Russian-German X-ray observatory, launched on July 13, and currently on a journey to its final staging point, a region of precarious orbital stability in the earth-Sun system called “L2”, about a million miles from earth along the earth-Sun line. Once it arrives at L2, SRG will survey the entire sky every six months over the next four years. SRG consists of two observing instruments. The Astronomical Roentgen Telescope X-ray Concentrator (ART-XC) instrument consists of 7 individual telescopes whichwill generate images of the X-ray sky in the energy band from 5 kilo-electronvolts up to 30 kilo-electronvolts, which is about 3 times higher in energy than most other imaging X-ray observatories, like ChandraXMM-Newton and Swift. ART-XC was developed by the Russian Academy of Sciences’ Space Research Institute, in cooperation with the Russian Federal Nuclear Centre; NASA’s Marshall Space Flight Center provided ART-XC’s X-Ray mirrors. The image above is the first light image from the 7 ART-XC telescopes, obtained on July 30, 2019. This image shows the well-known X-ray pulsar Cen X-3, a binary system in which a spinning neutron star (rotating once every 4.8 seconds) is in a 2-day orbit around Krzeminski’s star, a massive star about 20 times the mass of the Sun. ART-XC can also measure the time variation of the observed X-rays, and the plot on the bottom of the image clearly shows the 4.8 second X-ray variation of the pulsar as measured by ART-XC. eROSITA, developed by Germany’s Max Planck Institute, is the second instrument on SRG, and is expected to achieve first light in the coming weeks.

Published: August 12, 2019 

 

The new image obtained by ART-XC

During the ART-XC calibration observations on August 3, the collaboration received a new scientific image:

 Centaur X-3
The X-Ray pulsar Centaur X-3 (Cen X-3) in the ART-XC telescope central field of view.

As of August 7, 2019, the Spektr-RG spacecraft was continuing its flight to the L2 Sun – Earth system libration point area, the onboard equipment being adjusted. The ART-XC telescope creators expect to receive the images from the second telescope, eROSITA, to collate the fields of view of both telescopes.

eROSITA, the second telescope of the project was created in Germany. The spacecraft has already opened the lid used to cover the mirror systems entrance openings. eROSITA is expected to send its first images in mid-September.

Spektr-RG is a Russian-German joint project to create a space astrophysical observatory aimed to explore the Universe in the X-Ray electromagnetic radiation spectrum around the Sun – Earth system L2 point. The spacecraft was launched on July 13 2019 from the Baikonur Cosmodrome.

INTEGRAL coordinated observations of Cen X-3

31 July 2019 INTEGRAL is currently observing the High Mass X-ray Binary Cen X-3. The source is the target selected for the first light of the ART-XC detector onboard the Spektr-RG mission.

INTEGRAL observations will provide complementary information of the source at hard X-rays and will help to characterise the performance of the ART-XC detector in space. Spektr-RG was launched from the Baikonur Cosmodrome on 13 July 2019. We wish sucessful operations to our Spektr-RG colleagues.

Source: INTEGRAL ESA Mission

ART-XC First light

On July 30, 2019 the first images of Cen X-3 X-ray pulsar have been obtained with ART-XC telescope onboard Spektr-RG mission.

Quick-look data analysis demonstrated a strong pulsations with known period of 4.8 seconds.

 

Images of the X-ray pulsar Cen X-3 obtained with seven ART-XC telescope modules. The location of the images corresponds to the location of the telescope modules. Bottom panel: the pulse profile of Cen X-3 folded with the period of about 4.8 s, registered by the ART-XC telescope from this source.

More detailed investigations will be later presented in official press release.

Last, but not the least, there is a little film, showing how brightness of the pulsar changes – through the eyes of ART-XC