HEASARC: The Hidden Universe Revealed

The Hidden Universe Revealed

In its lonely halo orbit 1.5 million miles from earth, the Spektr-RG observatory (SRG for short) scans great circles on the sky around the Sun-Earth L2 point (the first Russian observatory to operate there). SRG carries two telescopes, eROSITA and ART-XC, and these two telescopes map out the entire X-ray Universe every six months. SRG has just finished its first all-sky X-ray survey, which lasted from December 8, 2019 until June 10, 2020. The ART-XC telescope provides the highest-resolution wide-field images in the high-energy X-ray band (4-30 keV), and so provides a revolutionary new view of the X-ray Universe. Because the high-energy X-rays that ART-XC observes can penetrate through vast amounts of dust, ART-XC can find obscured objects hidden to telescopes which operate in lower energy bands. The image above shows the very first all-sky map obtained by ART-XC, in the 4-12 keV band. ART-XC has already detected nearly 600 objects, about two thirds of which are within the Milky Way, and the remainder beyond our Galaxy. The bright areas in the upper left and lower right of the image are the ecliptic poles, which are more highly exposed due to SRG’s orbit around the Sun-Earth line. The all-sky survey will be repeated 7 more times over the next 3.5 years, building up exposure to detect ever-fainter sources and allowing scientists to monitor changes in the X-ray sky. ART-XC is expected to eventually find around 10 thousand hard X-ray sources, providing a unique census of actively feeding supermassive black holes and other strange objects. The ART-XC telescope was developed by the Space Research Institute(Moscow) and the Russian Federal Nuclear Center (Sarov), while its mirrors were fabricated by NASA’s Marshall Space Flight Center.

Published: June 22, 2020 https://heasarc.gsfc.nasa.gov/docs/objects/heapow/archive/large_scale_structure/art-xc_survey.html


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

HEASARC: The Launch of SRG

The image above shows the launch of Spectrum-Roentgen-Gamma from the Baikonur Cosmodrome in the Republic of Kazakhstan on July 13, 2019. Spectrum-Roentgen-Gamma (also called Spektr-RG, or SRG for short) is a Russian-German space observatory (with contributions from NASA), which will explore the entire high-energy X-ray Universe. The primary instrument on SRG is the “extended ROentgen Survey with an Imaging Telescope Array” telescope, better known as eROSITA. eROSITA will perform an unprecedented, 4-year long survey of the entire X-ray sky, greatly improving upon the only prior imaging all-sky X-ray survey, obtained by the German-US-UK ROSAT observatory in the early 1990s. The eROSITA survey will be obtained over a 5-times wider X-ray energy band, extending from 0.2 keV up to 10 keV, and to a much higher sensitivity than achieved by the ROSAT All-Sky Survey. The Astronomical Roentgen Telescope – X-ray Concentrator (or ART-XC) on SRG will expand the energy range of SRG to even higher energies, up 30 kilo-electron volts. One of the primary goals of SRG is to detect tens of thousands of distant galaxy clusters to determine the large scale structure in the Universe and test our understanding of the mysterious dark energy which drives the Universe apart. SRG will observe the Universe from a parking orbit at the Sun-Earth L2 point, a region of gravitational stability about a million miles behind Earth along the Sun-Earth axis. SRG will execute its 4-year all-sky survey by orbiting around the Sun-Earth axis every 4 hours. After this survey, SRG will spend 3 years taking detailed observations of individual celestial objects including galaxy clusters, active galactic nuclei, stars, neutron stars and black holes.

Published: July 15, 2019

On-line broadcast of launch – today (July 13, 2019) from 14:30 MSK

On-line broadcast of launch:

Launch schedule

15:30:57 MSK Liftoff
15:33:01 MSK Stage I separation
15:36:29 MSK Stage II separation
15:36:42 MSK Fairing separation
15:40:41 MSK Booster separates from stage III
15:46:41 MSK First booster engine firing, to lift the payload into a transfer orbit
17:08:24 MSK Second booster engine firing, spacecraft on the way to L2
17:30:58 MSK Booster separation from the payload

Launch postponed until July 13, 2019

The state commission that oversees the launch of Proton-M carrier rocket with DM-03 booster and Spektr-RG satellite telescope decided to postpone the launch of the Spektr-RG observatory to July 13, 2019 due to issues with rocket subsystem.

Final decision about a possibility of the launch will be provided by the state commission at morning of July 13, 2019.

Source (russian) at Roscosmos official site

Roscosmos: Pre-launch tests at Baikonur

Roscosmos and space industry specialists perform pre-launch tests of the Proton-M vehicle with the Spectr-RG observatory at the Baikonur cosmodrome.  In particular, a cycle of planned tests and additional checks of all the launch vehicle systems, the DM-03 upper stage and the observatory are carried out.

However, during the final phase of the ground tests, an issue on the launch missile was revealed, which required additional time to eliminate.

Source: Roscosmos


RIA Novosti reported that the issue with discharged battery has been resolved

The RIA Novosti news agency reported, that the discharged KhIT battery, which had required to postpone the launch of the Spektr-RG observatory to a backup date on July 12, was replaced by specialists at the Baikonur cosmodrome.

“The chemical current source has been replaced. The re-erect of the rocket to the launch pad is planned on July 8. The launch is scheduled on July 12 at 15.31 Moscow time,” said the agency source.