Active collaborative projects

2020/01 – Black holes accreting at extreme rates: radio follow up of eROSITA tidal disruption events and transient ultra-luminous X-ray sources

PIs: Gemma Anderson (ICRAR), Arne Rau (MPE)
Australian Collaborators: James Miller-Jones, Adelle Goodwin, Adela Kawka
eROSITA Collaborators: Adam Malyali, Zhu Liu, Joern Wilms, Iuliia Grotova
Australian Surveys/Instruments: AAT, ATCA

Summary: The release of gravitational energy when mass is suddenly dumped onto a black hole, powers some of the most explosive phenomena in the Universe. This is the most extreme example of a universal process called accretion, which is responsible for the growth of all astrophysical systems, from stars to galaxies. This project aims to understand how the most rapidly feeding black holes (accreting in the super-Eddington regime) produce powerful outflows, and to determine under what conditions these jets can be launched. We will perform radio follow-up of short-lived, explosive events to unveil when the jets are formed and how they evolve in real time. These include stellar-mass black holes rapidly consuming material torn off a nearby companion star (known as transient ultra-luminous X-ray sources), and supermassive black holes tearing apart unlucky stars that wander too close (known as tidal disruption events). The unrivalled capabilities of the new X-ray telescope eROSITA will allow us to discover thousands of such rapidly evolving systems. We will follow up many of these with Australian radio telescopes to explore in detail the connection between the infalling matter and the launching of jets in some of the most extreme environments known in the Universe.

2020/02 – Connecting HI and Xray absorption in distant AGN with FLASH/eRosita

PIs: Vanessa Moss (CSIRO), Mara Salvato (MPE) 
Australian Collaborators: Elaine Sadler, James Allison, Elizabeth Mahony, Emily Kerrison
eROSITA Collaborators: Andrea Merloni, Antonis Georgakakis, Johannes Buchner, Tom Dwelly
Australian Surveys/Instruments: FLASH HI 

Summary: We propose a joint CAASTRO/eROSITA project to investigate the nature of dense gas in the environment surrounding supermassive black holes, using HI absorption from ASKAP‐FLASH to measure the neutral gas and eROSITA to trace the hydrogen content via X‐rays. This project will enable us to shed light on the hidden gaseous regions near accreting black holes, and understand the role that neutral gas plays, alongside its eventual fate, in these active galaxies.

2020/03 – Supernova remnants, superbubbles, and the global structure of the interstellar medium in the Magellanic Clouds

PIs: Manami Sasaki (Dr Karl Remeis Observatory, Friedrich-Alexander-University Erlangen-Nürnberg), Lister Staveley-Smith (ICRAR)
Australian Collaborators: Miroslav Filipovic, Bärbel Koribalski
eROSITA Collaborators: Frank Haberl, Jürgen Kerp, Jonathan Knies, Kisetsu Tsuge, Federico Zangrandi
Australian Surveys/Instruments: ASKAP, ATCA, Parkes, MWA, and AAT 

Summary: The evolution of spiral galaxies is driven by star formation and matter cycle between the stars and the interstellar medium (ISM). Massive OB stars inject energy through their radiation, stellar winds, and finally by supernova (SN) explosions. Supernova remnants (SNRs) also act as recycling centres, returning elements forged in stars to the ISM. These processes are often correlated in space and time, generating superbubbles (SBs) with sizes of typically 100 − 1000 pc. By studying the physics of SNRs and SBs we will better understand the chemical composition and evolution of galaxies.


2020/05 – CLOSED / CONTINUED AS PROJECTS 2022/03 AND 2022/04

2020/06 – Radio and X-ray observations of Galactic SNR and SNR Candidates

PIs: Natasha Hurley-Walker (Curtin University), Werner Becker (MPE)
Australian Collaborators: Anne Green
eROSITA Collaborators: Francesco Camilloni
Australian Surveys/Instruments: GLEAM-X​ 

Summary: Supernova remnants (SNRs) are important contributors to the thermal, kinetic, and cosmic ray energy budget of the Milky Way, and also chemically enrich and shock the ISM, affecting star formation. Of the 2000 predicted SNRs in our Galaxy, fewer than 300 have been detected and confirmed over multiple wavelengths. Radio observations are responsible for the detection of over 90% of known and candidate SNRs, but full characterisation is only truly possible with X-ray observations, which give insights into the chemical composition of the shocked ejecta, position of the forward and reverse shocks, and allow ages to be estimated without ancillary data such as measurements of associated pulsars. Recent low-frequency radio surveys enabled the detection of 27 SNRs (Hurley-Walker et al., 2019). Current X-ray surveys are not sensitive enough to detect these objects, which are low surface-brightness, and often at higher Galactic latitudes. The eROSITA all-sky survey will characterise the X-ray emission from these objects, as well as ~300 proposed candidate SNRs in the literature, bringing us closer to detecting the full complement of SNRs predicted to exist in the Milky Way.  Additionally, the GLEAM-eXtended (GLEAM-X) survey will produce deeper, higher-resolution (1′) low-frequency images of the Galactic Plane, highly synergistic with the upcoming eROSITA observations.


2020/07 – Integral field spectroscopy of local eROSITA sources with the SAMI Galaxy Survey

PIs: Scott Croom (Usyd), Kirpal Nandra (MPE)
Australian Collaborators: Henry Poetrodjojo, SAMI team
eROSITA Collaborators: Andrea Merloni
Australian Surveys/Instruments: SAMI​​ 

Summary: This project aims to use the combined power of eROSITA and the SAMI integral field galaxy survey to further our understanding of the role of AGN in local galaxies.We will particularly focus on the nature of outflows driven by AGN and the excitation mechanisms in LINERS. To do this we will combine eFEDS eROSITA catalogues in the GAMA G09 region and SAMI emission line maps.

2020/08 – CLOSED - The Radio/X-ray connection in Radio-loud AGN

2020/09 – COMPLETED - The radio/X-ray connection in the Abell 3391/95 field

2020/10 – Radio properties of X-ray selected galaxy clusters with EMU and eROSITA

PIs: Marcus Brueggen (Hamburg Uni), Ray Norris (WSU)
eROSITA Collaborators: Thomas Reiprich, Kathrin Böckmann, Angie Veronika
Australian Surveys/Instruments: ASKAP/EMU​​​​​ 

Summary: We propose to study the radio properties of X-ray selected galaxy clusters. This includes studies of radio haloes, radio relics, tailed radio galaxies, as well as cluster central radio AGN and their correlation with morphological X-ray parameters. The X-ray and radio views of galaxy clusters are highly complementary, tracing the hot thermal and relativistic particle populations, respectively. ​

2020/11 – SkyMapper DR3 as Reference Sky for GROND follow-up of eROSITA_DE Transients

PIs: Christian Wolf (ANU), Arne Rau (MPE)
Australian Collaborators: Chris Onken
eROSITA Collaborators: Mara Salvato, Axel Schwope
Australian Surveys/Instruments: SkyMapper​​​​​​ 

Summary: The sensitivity and observing cadence of eROSITA will open a new window in to the X-ray transient and variable sky. One of the main challenges will be the rapid selection of the most interesting sources, e.g. Tidal Disruption Events and Fast X-ray Flares, from among the general population of variable X-ray sources dominated by AGN and stars. To address this, the eROSITA_DE transient follow-up will utilize its proprietary Target of Opportunity access to the GROND imager at the MPG 2.2m telescope at La Silla observatory. This instrument provides simultaneous optical/NIR imaging in 7-bands with a typical a typical delay of 24-48hr after the eROSITA detection.In order to identify and study the optical/NIR counterparts a sufficiently deep reference data set is needed. Here, we propose to use SkyMapper DR3 imaging data and source catalogs in the g,r,i, and z bands as reference sky for the GROND follow-up of eROSITA transients. The source catalog will allow to identify variable or new sources through comparison of the photometric measurements. Imaging data will be utilized for image subtraction, which is particularly important for nuclear transients such as Tidal Disruption Events.

2020/12 – Joint X-ray and spectroscopic monitoring of AGN in the SEP

PIs: Scott Croom (USYD), Kirpal Nandra (MPE)
eROSITA Collaborators: David Bogensberger, Mara Salvato, Teng Liu, Julien Wolf, Johan Comparat
Australian Surveys/Instruments: AAOmega ​​​​​​ 

Summary: We propose to seek spectroscopic monitoring using AAOmega of eROSITA-detected AGN in the South Ecliptic Pole (SEP). This is a unique region of the sky which, due to the eROSITA scan pattern, obtains intensive variability monitoring. The ~1 deg2 region at the pole itself is currently being covered once every four hours, and in principle this should continue throughout the entire 4-year period of the eROSITA All-Sky survey (eRASS). The resulting X-ray variability dataset is unique, but to exploit it fully requires optical spectroscopy for the identification and characterisation of the sources, determination of black hole masses, and joint spectroscopic variability monitoring. AAOmega provides the ideal complement to eROSITA, with its large field of view able to cover the most intensively monitored region in a single shot. Here we propose a joint program of X-ray and optical spectroscopic monitoring to investigate the relationship between the X-ray variability and fundamental parameters such as the black hole mass, accretion rate, and perhaps black hole spin. The eROSITA monitoring dataset will also likely reveal more dramatic variability such as “changing look” events, tidal disruption events (TDEs) and other transients, some of which may reveal new astrophysical phenomena. ​

2020/13 – COMPLETED - The First Mpc Scale Recollimating AGN Jets in NGC 2663

2020/14 – PeVatrons at X-ray Energies

PIs: Gavin Rowell (Uni Adelaide), Manami Sasaki (Universität Erlangen-Nürnberg​)
Australian Collaborators: Miroslav Filipovic, Sabrina Einecke, Katie Jameson, Sanja Lazarevic
eROSITA Collaborators: Gerd Püehlhofer, Miltos Michailidis, Konstantin Haubner
Australian Surveys/Instruments: GLEAM ​​​​​​ 

Summary: With recent advances in γ-ray telescopes coupled with new radio and X-ray surveys, it is now finally possible to probe the origin of rare PeV Cosmic Rays (CR). The search for PeV CRs is a major legacy project for HESS and the CTA. To understand the TeV γ-ray images, we need to visualise the interstellar gas in 3D to create the model target material for CR collisions. The 3D picture will be built from the high-resolution surveys with the Mopra radio telescope, SGPS and GASKAP. Then, by modelling the propagation of CRs from their source into this gas and producing model γ-ray maps and spectra to compare with broadband data from radio to X-rays, we can infer the location of the CR accelerator and its age. To confidently identify the accelerator and its properties, we need eROSITA. X-ray results from eROSITA will provide crucial information on the competing γ-rays from electrons via the inverse Compton processes, as the X-rays constrain electrons and magnetic field properties of the accelerator via synchrotron emission.

2020/15 – Unifying the Macro and Micro properties of AGN Feedback in our Nearest Radio Galaxy

PIs: Benjamin McKinley (Curtin), Jeremy Sanders (MPE​)
Australian Collaborators: Steven Tingay
eROSITA Collaborators: Thomas Reiprich, Kirpal Nandra
Australian Surveys/Instruments: MWA ​​​​​​ 

Summary: We anticipate that the wide field of view and increased sensitivity of eRosita will allow us to accurately map out the large-scale X-ray emission of Centaurus A. This will allow us to study the properties of the hot halo out to the thermalisation radius observed with the MWA and to more accurately constrain the properties of the AGN wind. Armed with the radio and X-ray properties of Centaurus A we will be able to determine a more accurate picture of the AGN feedback processes at work and compare our findings with observations of AGN at higher redshifts, where the intricate details that are observable in our nearest radio galaxy remain hidden.

2020/16 – Searching for faint black holes and neutron stars in globular clusters

PIs: Arash Bahramian (Curtin/ICRAR), Joern Wilms (ECAP & Dr. Karl Remeis-Sternwarte, FAU Erlangen-Nürnberg)
Australian Collaborators: James Miller-Jones
eROSITA Collaborators: Axel Schwope, Arne Rau, Gloria Sala
Australian Surveys/Instruments: ATCA 

Summary: eROSITA_DE covers 75 well characterized Galactic globular clusters, 67 of which are well accessible by ATCA, and 51 of which are closer than 12 kpc, allowing us to reach a more desirable X-ray luminosity threshold for sensitivity to “very faint” X-ray transient (VFXT) outbursts. This provides us with a unique, rich sample of clusters to search for black hole VFXT systems for the first time. Rapid Target-of-Opportunity radio observations of a globular cluster transient with ATCA soon after a detection by eROSITA would allow us to characterize the disk-jet coupling in the transient and determine tentative classification of the object. Based on the findings in the ATCA observation, we will plan further follow up observations (e.g., Xray observations via Swift). The project will advance our understanding of the duty cycle, population and nature of very faint X-ray binaries and accreting black holes in globular clusters.

2020/17 – What causes star formation in high redshift BCGs, major mergers with gas rich galaxies or runaway cooling flows?

PIs: Chris Lidman (ANU), Esra Bulbul (MPE)
eROSITA Collaborators: Esra Bulbul, Jacob-Ider Chitham
Additional participants: Tracy Webb, Allison Noble
Australian Surveys/Instruments: AAT

Summary:  Sitting at the centre of most clusters is a single massive galaxy, known as the Brightest Cluster Galaxy (BCG). We wish to examine the X-ray morphology of clusters that contain star forming BCGs. All the BCGs have redshifts from follow-up program with 2dF+AAOmega, and many of them have CO measurements from ALMA. The peak of the X-ray emission will be compared to the location of BCG and the location of the CO gas. The control sample will be BCGs that are not star forming. All the BCGs come from the SpARCS survey.

2020/18 – Multiwavelength Constraints on the Nature of Fast Radio Bursts

2021/01 – Discovery of a double radio relic in the PSZ2 G277.93+12.34 galaxy cluster

PIs: Bärbel Koribalski  (CSIRO, Western Sydney Uni), Marcus Brüggen (Uni Hambürg)
eROSITA Collaborators: Thomas Reiprich, Angie Veronica
Australian Surveys/Instruments: ASKAP, MWA

Summary: We propose to analyse eROSITA X-ray data for a new double relic (diameter ~16 arcmin) serendipitously discovered in recently obtained MeerKAT radio continuum data. The relics are associated with the galaxy cluster PSZ2 G277.93+12.34 and likely filled with hot gas traced by X-ray emission. A narrow angle tail radio galaxy (z ~ 0.15) is detected just east of the northern relic. Adopting the same redshift for the cluster we estimate a relic separation of 1.5 Mpc. While the MeerKAT radio continuum map is in hand, provided by SARAO, further calibration and imaging is required to obtain spectral indices and polarisation estimates. Relics are known to attain polarisation fraction of up to 70%. We aim to compare our radio and X-ray data of the PSZ2 cluster with numerical simulations from the Magneticum project.

2022/01 – Linking the spatially resolved properties of galaxies to X-ray proxies forgroup environment using SAMI and eROSITA

PIs: Stefania Barsanti (ANU), Esra Bulbul (MPE)
Australian Collaborators: Matthew Colless, Matt Owers, SAMI team, GAMA team
eROSITA Collaborators: Esra Bulbul and her team
Australian Surveys/Instruments: SAMI datacubes, GAMA catalogues

Summary: In this project we aim to investigate the environmental mechanisms causing star formation quenching in nearby galaxy groups. We will study the dependence of spatially resolved properties of the galaxies on the X-ray proxies tracing the group environment. We will take advantage of (i) the eROSITA Final Equatorial Depth Survey (eFEDS) catalogue for the GAMA G09 region and the preliminary eRASS1 catalogue for the GAMA G12 and G15 regions to probe the X-ray properties of the groups; (ii) the GAMA survey for the optical selection of the groups (Robotham et al., 2011); and (iii) the SAMI Galaxy Survey for the spatially resolved galaxy properties (Bryant et al., 2015). We will analyse how star formation, morphological and kinematic properties of the galaxies are affected by the conditions of their host halo, such as its X-ray luminosity, temperature and the presence of substructures. The use of X-ray proxies for the group environment will also allow us to study any bias with respect to the optical environment metrics. This work will shed light on how the spatially resolved properties of galaxies are affected by the group environment using Xray proxies, advancing our understanding of galaxy evolution.

2022/02 – Stars with eROSITA and ASKAP

PIs: Laura Driessen (CSIRO / University of Sydney), Jan Robrade (Hamburger Sternwarte)
Australian Collaborators: Tara Murphy, George Heald, Andrew Zic, Emil Lenc, Joshua Pritchard
eROSITA Collaborators: Beate Stelzer
Australian Surveys/Instruments: ASKAP and potentially other radio telescopes (e.g. ATCA) for further follow-up of discoveries

Summary: We propose to use ASKAP and eROSITA data to search for and investigate stellar radio sources. The sensitivity and fields of view of new radio telescopes such as ASKAP and LOFAR are substantially increasing the number and type of known radio stellar sources. We can use these discoveries, in combination with X-ray observations, to investigate the coronae of stars and the physics behind the X-ray and radio emission. Recent work has shown that the connection between the X-ray and radio emission from stellar sources does not match our expectations for these sources, and ASKAP and eROSITA are well-placed to determine the cause of the mismatch. We propose to use eROSITA to determine the X-ray luminosities of ASKAP stars found through circular polarisation searches, to find new stellar radio sources by matching Gaia, eROSITA and ASKAP sources, and to determine the radio luminosities of eROSITA X-ray stars. Our goal is to determine the population of stars that emit in the radio and to investigate the emission mechanisms of stellar radio sources.

2022/03 – Optical/X-ray behavior of 6dF/SkyMapper-selected Changing-Look AGN

PIs: Christian Wolf (ANU), Mirko Krumpe (AIP)
Australian Collaborators: Christopher Onken (ANU), Neelesh Amrutha (ANU), Douglas Thompson (ANU), Dr. Katie Auchettl (Melbourne Uni), Wei Jeat Hon (Melbourne Uni)
eROSITA Collaborators: Mara Salvato (MPE), David Homan (AIP), Dusan Tubin (AIP), Sabina
Bahic (AIP), Georg Lamer (AIP), Jörn Wilms (Sternwarte Uni Erlangen)
Australian Surveys/Instruments: ANU 2.3m telescope and SkyMapper data

Summary: This project aims to study a well-defined CL-AGN sample, which was created by combining spectral types of AGN from 6dFGS observed in 2001 to 2007 with the nuclear colours of these objects from the SkyMapper Southern Survey DR3 observed in 2015 to 2019.

2022/04 – True type-2’s among ~5,000 6dF-selected type-1/2 AGN

PIs: Christian Wolf (ANU), Mirko Krumpe (AIP)
Australian Collaborators: Christopher Onken (ANU), Douglas Thompson (ANU), Neelesh Amrutha (ANU), Dr. Katie Auchettl (Melbourne Uni), Wei Jeat Hon (Melbourne Uni)
eROSITA Collaborators: Mara Salvato (MPE), David Homan (AIP), Dusan Tubin (AIP), Georg Lamer (AIP), Jörn Wilms (Sternwarte Uni Erlangen)
Australian Surveys/Instruments: Primarily, the new 6dFGS AGN catalogue by Hon, Webster & Wolf, with fitted lines and SkyMapper data used for calibrating 6dF spectra

Summary: The canonical unification scheme of AGN stipulates that Seyfert 2 galaxies are essentially
Seyfert 1 galaxies that appear extinguished by a dusty torus (Urry & Padovani 1995). It has also been suggested that subtypes such as Seyfert 1.8/9 may harbour physically normal Sy-1 nuclei that are moderately obscured by host galaxy dust (Elitzur+2014). However, Changing-Look AGN (CL-AGN) have also highlighted that some Seyfert 2 galaxies did not suffer from orientation-induced extinction, but rather had low accretion rates. Separately, “naked” Sy-2 AGN with little obscuration and little accretion were also found (Tran 2001, 2003; Panessa & Bassani 2002; Laor 2003). This project aims to study a well-defined z<0.1 AGN sample with a focus on addressing the nature of Sy-2 galaxies.

2023/01 - A radio/X-ray study of the "Dancing Ghosts"

PIs: Ray Norris (WSU/CSIRO), Marcus Brueggen (U. Hamburg)
Australian Collaborators: Velibor Velovic (WSU), Miroslav Filipovic (WSU), Luke Barnes (WSU), Andrew Hopkins (MQ), Michelle Boyce (U. Manitoba, Canada), Chris O’Dea (U. Manitoba, Canada), Bill Cotton (NRAO, USA), Jim Condon (NRAO, USA)
eROSITA Collaborators: Thomas Reiprich (U.Bonn)
Australian Surveys/Instruments: Survey data from EMU Pilot Survey

Summary: We have observed the ‘Dancing Ghosts’ peculiar galaxy pair PKS 2130–538 with ASKAP (as part of the EMU Pilot Survey) and with MeerKAT. This complex, of overlapping and possibly interacting jets and lobes results from two Active Galactic Nuclei hosts in the Abell 3785 galaxy cluster. We also detect a number of collimated synchrotron threads, originating from the AGN lobes. Such threads were unknown until the advent of next-generation telescopes such as ASKAP and MeerKAT. We wish to augment these data with X-ray data from eROSITA to understand the physical processes that generate the peculiar morphology of this source and understand the formation of the collimated synchrotron threads.

2023/02 - Radio follow-up of X-ray quasi-periodic eruptions

PIs: Adelle Goodwin (Curtin/ICRAR), Riccardo Arcodia (MIT)
Australian Collaborators: Gemma Anderson (Curtin)
eROSITA Collaborators: Andrea Merloni, Arne Rau, Zhu Liu, Adam Malyali(MPE)
Australian Surveys/Instruments: Australia Telescope Compact Array  

SummaryX-ray quasi-periodic eruptions (QPEs) are a newly discovered type of X-ray transient representing the frontier of variability in accreting massive black holes. QPEs are sources which with fast and repeating quasi-periodic soft X-ray bursts characterised by a flux increase of more than one order of magnitude over the quiescent plateau. QPEs offer a new channel to activate the nuclei of low-mass galaxies, a poorly understood regime of the black hole-galaxy co-evolution.  

Little is currently known about the radio properties of QPE sources since to date, not all sources have been observed in the radio, and not all sources were detected if they were observed. The QPE sources that were observed and detected in some radio bands seem steady and weak, showing signs of small amplitude radio variability. With the origin scenario of QPEs being unknown, it is important to fully constrain these sources in the radio, especially given the emission pattern of Tidal Disruption Events in the radio, in which radio afterglow emission can often last for years after the event.