An appetizer to the all-sky banquet

First data of the eROSITA X-ray telescope now released to the public

The “eFEDS” (the eROSITA Final Equatorial Depth Survey) was designed as a preview to the final eROSITA all-sky survey for a small patch of the sky. The top panel shows all sources, color-coded by the energy of the photons. The inset is a zoom onto a "supercluster", i.e. a conglomeration of clusters of galaxies about to merge. In bottom panel, all stars and AGN (i.e. all the point sources) have been filtered out from the eFEDS X-ray image. What is left is the diffuse emission from clusters and groups of galaxies, the matter in between, and the halo of the Milky Way in front. As such, it gives a visual illustration of the large-scale structure that is almost impossible to gain otherwise.

As announced during the 2021 meeting of the European Astronomical Society, the German eROSITA collaboration has released the first set of data taken with the eROSITA X-ray telescope onboard the Russian-German space observatory Spektrum-RG (SRG). For the first time, astronomers throughout the world will have the chance to download and analyse data from this powerful new telescope. The Early Data Release consisting of data taken during the so-called ‘Calibration and Performance Verification Phase’ in mid-September to mid-December 2019 will be accompanied by the publication of 35 eROSITA science papers by the German eROSITA Consortium on the arXiv preprint server, with these and more to be published in a forthcoming special issue of the journal Astronomy and Astrophysics. Four of those are led by scientists from the University of Tübingen, one of the five core institutions which contributed to the development of the mission.

“This is the first public release of SRG/eROSITA data,” says Andrea Merloni, eROSITA principal investigator at the Max Planck Institute for Extraterrestrial Physics. “Since the start of observations with the X-ray telescope at the end of 2019, we have been impressed with the high-quality data, which have already led to numerous astronomical discoveries and breakthroughs. Now is the time to give astronomers worldwide a first taste of what is to come over the next few years. This is going to open up a whole new Universe of possibilities.”

The eROSITA survey 

The eROSITA X-ray telescope on-board the SRG spacecraft is primarily a survey machine and will be scanning entire sky until the end of 2023 to conduct the most sensitive all-sky X-ray survey to date. The current data release contains almost 100 individual observations of 29 distinct fields taken before the start of the all-sky scans and thus is just an appetizer for an all sky banquet. Still, over thirty papers led by the German eROSITA Consortium mostly based on EDR data accompain release “We are very excited to be part of the eROSITA consortium and take part in exploration of the data from this wonderful instrument”, says Andrea Santangelo, head of the high energy group at the Institute for Astronomy and Astrophysics (IAAT) at the University of Tübingen. “Bear in mind that the current release is just a tiny fraction of what has already been observed and more is to come”, adds Santangelo. 

Galactic science with eROSITA

“Most of the objects seen by eROSITA are Active Galactic nuclei at the edge of the Universe, and normal, hydrogen-burning stars in our galaxy which, among other local objects are the main focus of research in Tübingen. I am particularly inspired to study emission from the smallest stars that are barely massive enough to ignite nuclear fusion. Those are numerous but very cool and faint, so it is extremely hard to catch them unless in a sensitive all sky survey like that provided by eROSITA”, says Professor Beate Stelzer who leads the space-based astrophysics group at IAAT. "Much rarer objects are also expected to pop up in the survey", adds Victor Doroshenko leading compact object studies with eROSITA at IAAT: “For instance, we expect to detect several tens of the X-ray binaries which comprise a neutron star or a black hole that is fed by matter supplied by a  companion star, and, in fact, started to see those already. At the end of the survey the population of known objects of this type will be doubled which will help to learn more about their properties at low fluxes, their origin and evolution. Other surprises like the recently discovered eROSITA bubbles, a diffuse X-ray emission pervading a large part of the Milky Way can certainly also be expected”. 

Impact of the pandemic

The COVID-19 pandemic, which has had an impact on so many professional activities, has also complicated matters for the eROSITA team. “Only six months after the start of eROSITA science observations, the global pandemic forced us to modify almost all aspects of our work,” says Andrea Merloni. “Even operating the telescope 1.5 million kilometers away had to be done from home. I’d like to think that the unique opportunity of working with a brand new ‘discovery machine’ has helped many of us to keep some sort of focus or balance – at least it did for me. eROSITA has given us many reasons to celebrate, and we are all looking forward to having a real party soon.”

Further information

eROSITA is the primary instrument aboard Spektrum-RG (SRG), a joint Russian-German science mission supported by the Russian Space Agency (Roskosmos), in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI), and the German Space Agency at DLR (Deutsches Zentrum für Luft- und Raumfahrt). The SRG spacecraft was built by Lavochkin Association (NPOL) and its subcontractors, and is operated by NPOL with support from the Max-Planck Institute for Extraterrestrial Physics (MPE).

The development and construction of the eROSITA X-ray instrument was led by the Max Planck Institute for Extraterrestrial Physics (MPE), with contributions from the Dr. Karl Remeis Observatory Bamberg, the University of Hamburg Observatory, the Leibniz Institute for Astrophysics Potsdam (AIP), and the Institute for Astronomy and Astrophysics of the University of Tübingen, with the support of DLR and the Max Planck Society. The Argelander Institute for Astronomy of the University of Bonn and the Ludwig-Maximilians-Universität Munich also participated in the science preparation for eROSITA.

Press release of the MPI for Extraterrestrial Physics/Victor Doroshenko, University of Tübingen

The official press release by eROSITA consortium regarding the early data release is available at https://www.mpe.mpg.de/7710163/news20210628 

The data itself is accessible via the eROSITA data archive at MPE at

More information: 

The eROSITA EDR is available here: 

Meet the eROSITA team: https://www.mpe.mpg.de/news/press_releases/news20210628/news20210628-team 

Public eROSITA pages at MPE: https://www.mpe.mpg.de/eROSITA 

eROSITA science papers: 
Associated suite of papers led by the German eROSITA Consortium mainly focussing on EDR observations. These papers and some more will form part of a A&A Special Issue: "The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission" that will be published later in the year.

Webpage: https://www.mpe.mpg.de/7650552/news20210628 


University of Tuebingen:
Andrea Santangelo
Head of the High energy Astrophysics at Institute for Astronomy and Astrophysics (IAAT), University of Tubingen
+49 (0)7071 29 76128
santangelospam prevention@astro.uni-tuebingen.de 

Beate Stelzer 
Professor for space based, observational astrophysics at Institute for Astronomy and Astrophysics (IAAT), University of Tubingen
+49 (0)7071 29 76132
stelzerspam prevention@astro.uni-tuebingen.de 

Victor Doroshenko
Scientific assistant of the head of the High energy Astrophysics at the Institute for Astronomy and Astrophysics, University of Tubingen
+49 (0)7071 29 74980
doroshvspam prevention@astro.uni-tuebingen.de 

MPE, Garching
Andrea Merloni 
eROSITA PI, Max Planck Institute for Extraterrestrial Physics
+49 (0)89 30000-3893 
amspam prevention@mpe.mpg.de 

Mara Salvato 
eROSITA spokesperson, Max Planck Institute for Extraterrestrial Physics 
+49 (0)89 30000-3815 
maraspam prevention@mpe.mpg.de