Welcome

• Vadim Burwitz (MPE)

Room: New Seminar Room

eROSITA Overview

• Andrea Merloni (MPE)

Room: New Seminar Room I will present a brief overview of the eROSITA science program, with particular emphasis on the all-sky survey, and describe how the eROSITA X-ray data can be used to open up new discovery spaces across several areas of high-energy astrophysics.

How eROSITA came to be !

• Peter Predehl (MPE)

Room: New Seminar Room eROSITA is an X-ray telescope on the Russian-German space mission Spektrum-Röntgen-Gamma. It was launched from the Russian Baikonur Cosmodrome on 13 July 2019 and has been orbiting the Lagrange point Earth-Sun L2 - 1.5 million kilometers away from Earth in the direction of the sun - since October 2019. The scientific concept of eROSITA was to scan the entire sky eight times over the course of four years in order to discover 100,000 galaxy clusters. This is particularly important as these are the most massive structures in the universe, which can help us track their growth over billions of years and determine the influence of dark matter and dark energy. In addition, we have discovered millions of new X-ray sources, from all kinds of objects in the Milky Way to the active centers of the most distant galaxies. eROSITA consists of seven identical telescopes: seven Wolter telescopes, each with 54 nested cylindrical mirrors, focusing X-ray light onto seven X-ray sensitive CCD cameras. A complex system of radiators and heat pipes cools the CCDs to temperatures below -80 °C. Nine large electronic boxes are used for data processing, instrument control, and data storage. In addition, there are two star sensors to determine the alignment of the telescope, kilometers of cable, and much more, weighing over 800 kg in total. All of this was designed, developed, built, and tested at MPE.

eROSITA Cameras

• Norbert Meidinger (MPE)

Room: New Seminar Room The seven eROSITA cameras are a further development of the PN-camera on ESA's XMM-Newton satellite. The eROSITA camera concept and design are explained, and the development is described. Its key component is the silicon PN-CCD detector, which was custom-developed for the eROSITA project. The most important scientific parameters are the energy, spatial, and time resolution, as well as the quantum efficiency and long-term stability. I describe the measured properties and performance of the cameras and discuss their advantages and disadvantages. Finally, expected and unexpected effects during camera operation in space are presented, and I conclude with a recent application of the eROSITA detector for the Einstein Probe satellite.

eROSITA Optics

• Peter Friedrich (MPE)

Room: New Seminar Room eROSITA's X-ray optics consist of lightweight, replicated gold-coated nickel shells that follow the Wolter-1 design. Each of the seven identical mirror assemblies consists of 54 nested mirror shells with different diameters. The mirror assemblies with a focal length of 1.6 m are arranged in a hexagonal configuration and form a compact telescope resting on a satellite platform. The lecture starts with a general introduction to X-ray optics and gives an overview of different manufacturing techniques of X-ray mirrors. The focus will be on the design, development, testing, and performance of the eROSITA mirror modules, complemented by a description of the "baffle" in front of the optics. The baffle design is closely linked to the design of the optics as it ensures that a certain type of stray light from the optics is suppressed. Finally, some sky images taken by eROSITA are shown to demonstrate the optical performance in space.

eROSITA Calibration

• Konrad Dennerl (MPE)

Room: New Seminar Room The power of eROSITA (extended ROentgen Survey with an Imaging Telescope Array), the soft X-ray instrument on the Russian–German Spectrum–Roentgen–Gamma (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 X-ray telescope modules, each composed of 54 paraboloid/hyperboloid mirror shells in a Wolter–I geometry, to focus the X–rays through optical blocking filters onto PN-CCDs with a total of 1 million pixels, providing a spectral resolution of 60 – 160 eV FWHM over an energy range 0.2 – 8 keV and a 1-degree field of view at a time resolution of 50 ms. In order to make full scientific use of the unique capabilities of eROSITA, it is essential to know quantitatively how the instrument modifies the incident signal. Therefore, all of its components have to be calibrated. I will report on the extensive and often challenging calibration activities performed on ground and in space.

eROSITA Operations / Data Analysis

• Miriam Ramos-Ceja (MPE)

Room: New Seminar Room The eROSITA ground operations comprise the areas of mission planning, telescope operation, and data reception, the operation of the data processing pipeline, and the creation of tools for data access and interactive data analysis. All these activities take place at and are the responsibility of MPE. Since its launch, eROSITA spent almost 1,000 days in nominal operations. During this time, the eROSITA operations team had a daily basis interaction in real-time with Mission Control in Moscow to carry out routine, maintenance, and contingency operations, as well as the downlink of the observed data. The eROSITA data processing pipeline consists of modules for data ingestion, event calibration, exposure calculation, source detection, and the creation of high-level source-specific data products. It is operated at MPE, and the data products are released to the collaboration members and the public. A subset of the software tasks comprising the data analysis pipeline also functions as interactive data analysis tools for scientists who are interested in eROSITA data. These can be grouped into tasks for X-ray event calibration, selection and binning, exposure, background and sensitivity map creation, and source detection. In this talk, I will show how the daily operations of eROSITA were carried out during nominal operations. A tour of the eROSITA control room will be possible. Furthermore, I will guide you through the process of how the observed X-ray photons are transformed into FITS files that you can analyze and use for your research.

Overview Clusters of Galaxies

• Esra Bulbul (MPE)

Room: New Seminar Room A significant milestone in X-ray survey science was achieved with the successful launch of eROSITA in July 2019. The German-built eROSITA X-ray telescope, on board the Russian-German Spectrum-RG (SRG) mission, operates within the 0.2-8 keV range and has produced the largest ICM-detected catalogs of galaxy clusters and groups through its All-Sky Surveys. The first eROSITA all-sky survey, with over 10,000 confirmed clusters, is pivotal in cluster astrophysics. I will give an overview of the physical properties of clusters of galaxies and galaxy groups and present rich cluster science eROSITA initiated.

Clusters: Data analysis

• Jeremy Sanders (MPE)

Room: New Seminar Room The primary mission of eROSITA is to detect clusters of galaxies in order to measure cosmological parameters. In order to build a cosmological model, we also need well-characterized X-ray mass measurements. Therefore, detecting clusters and measuring their properties is therefore a very important aspect of eROSITA data analysis. We will describe how clusters are detected in the eROSITA sky survey by the standard detection pipeline. Measuring the properties of clusters requires a combination of imaging and spectral analyses. We will discuss the MBProj2D (Multi-Band Projector in 2D), a Python package that simultaneously models clusters in multiple energy bands to measure radial profiles of their physical properties. We will also discuss the accurate spectral fitting of clusters.

Hands-on Session Clusters of Galaxies

• Jeremy Sanders (MPE)
• Xiaoyuan Zhang (MPE)
• Ang Liu (MPE)
• Esra Bulbul (MPE)

Room: New Seminar Room We will guide the attendees through measuring the properties of clusters of galaxies. The session will focus on fitting images of clusters of galaxies with MBProj2D to obtain profiles of their physical properties, such as density and gas mass. This will include extracting images, setting up a model, fitting it, and interpreting the results. We will also cover the extraction and fitting of spectra from clusters.

White Dwarfs

• Susanne Friedrich (MPE)

Room: New Seminar Room White dwarfs are the final state of stellar evolution of main-sequence stars with masses from about 0.1 to 10 solar masses. After the hydrogen-fusing period, the star expands to a red giant, and helium fuses to carbon and oxygen in its core. Depending on its mass, no further fusion is possible, and the red giant sheds its outer layers so that the core is exposed. The mass of these remnants is comparable to the sun’s, but their diameter is about the same as that of the Earth. The only energy source of a white dwarf is its residual thermal energy. A thin atmosphere of a few hundred meters in height, composed mainly of hydrogen and/or helium with sometimes traces of heavier elements, covers the core. Surface temperatures range from about 100,000 K to 4000 K. Only hot white dwarfs with surface temperatures above 30,000 K can be observed in soft X-rays or in extreme UV.

Diffuse Emission

• Gabriele Ponti (MPE)

Room: New Seminar Room The X-ray data from the eROSITA (extended ROetgen Survey with an Imaging Telescope Array) all sky survey have revealed a rich array of X-ray sources from point sources, extended sources, as well as diffuse emission. I will discuss the various components contributing to the diffuse X-ray emission, going from the emission from the Heliosphere to the emission on Galactic scales and beyond.

Hands-on Session White Dwarfs / Diffuse Emission

• Susanne Friedrich (MPE)
• Gabriele Ponti (MPE)
• Michael Yeung (Max Planck Institute for Extraterrestrial Physics)
• Xueying Zheng

Room: New Seminar Room During the hands-on session, we will learn how to create spectra of point sources and diffuse emission from the X-ray photons collected by eROSITA. Then, we will extract some physical properties of white dwarfs and diffuse emission by fitting the spectra with physical models. During the session, there will be plenty of space to ask questions.

Overview AGN

• Johannes Buchner (MPE)
• David Kaltenbrunner (MPE)
• Pietro Baldini (MPE)

Room: New Seminar Room This lecture has three parts: 1) introduction to Active Galactic Nuclei 2) tidal disruption events and other super-massive black hole transients 3) High-mass X-ray binaries Active galactic nuclei dominate the source population of eROSITA, with over a million point sources. In the extreme gravitational environment of black holes, gas accretion is accompanied by emission across the wavelength spectrum. eROSITA studies range from understanding this central engine, including the hot plasma emitting X-rays, the special viewpoint of blazars, transients such as sudden turn-on caused by the tidal disruption of stars, and characterizing the galactic nuclei and their cosmic web environment conducive to triggering black hole growth.

Spectral fitting of point sources

• Pietro Baldini (MPE)
• Zsofi Igo (MPE)
• David Kaltenbrunner (MPE)
• Johannes Buchner (MPE)

Room: New Seminar Room Concepts presented include the instrumentation response, the linear modelling approximation, Poisson count statistics and the Gaussian approximation, data re-binning, visualisation techniques, handling backgrounds, Bayesian and frequentist viewpoints, uncertainty quantification of model parameters, model checking, model comparison, and inferring population distributions.

Hands-on Session AGNs

• Johannes Buchner (MPE)
• David Kaltenbrunner (MPE)
• Zsofi Igo (MPE)
• Pietro Baldini (MPE)

Room: New Seminar Room

Social Dinner

Multiwavelength identification of counterparts to X-ray sources - overview

• Mara Salvato (MPE)

Room: New Seminar Room During this session, we will discuss all the facts that may undermine the correct identification of the multiwavelength counterparts to X-ray sources, such as X-ray catalog properties, ancillary data characteristics, and type of X-ray sources (Galactic, extragalactic). We will then discuss how to make the correct identification of counterparts to X-ray data. During the hands-on session, we will learn how to identify the most likely counterparts to the eROSITA/eFEDS sources using NWAY and different ancillary data. For this purpose, you need to have NWaY installed and tested. In addition, please download the file Number 4 in this page : https://erosita.mpe.mpg.de/edr/eROSITAObservations/Catalogues/

Multiwavelength identification of counterparts to X-ray sources - Data Analysis

• Mara Salvato (MPE)

Room: New Seminar Room

Hands-on Session Multiwavelength identification of counterparts to X-ray sources

• Mara Salvato (MPE)

Room: New Seminar Room We will also have hands-on experience using NWAY (Salvato et al. 2018), a Bayesian algorithm that can provide a reliable association between catalogs and account for externally computed priors. make sure to download also the DOC directory in NWAY (https://github.com/JohannesBuchner/nway) https://github.com/JohannesBuchner/nway/tree/master/doc