High Energy Astrophysics at Masaryk University

The High Energy Astrophysics Group is a research group in the Department of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University, Brno, Czech Republic. We are an international research group focused on the hot and energetic Universe over multiple wavelengths and physical scales. We bridge obvervational, theoretical, and computational fields over a broad array of disciplines.

Horizons 2020

Studying the Hot Universe

Most of the Universe consists of dark energy and dark matter, which are hidden from our view. However, even most of the “ordinary matter”, made of standard-model particles, remains unseen and unexplored. In the course of structure formation, only a small fraction of the baryons turned into stars - most remain in the form of a hot, strongly ionised, low-density, X-ray emitting plasma. In the innermost parts of galaxies this plasma is often referred to as interstellar medium (ISM), at large radii, well beyond the stellar component, as circumgalactic medium (CGM), in groups of galaxies as intragroup medium (IGrM), in clusters of galaxies as intracluster medium (ICM), and in the filaments of the cosmic web as intergalactic medium (IGM) or warm-hot intergalactic medium (WHIM). Since the hot phases of all these media share crucial similarities, we will refer to them at all scales as hot atmospheres. They can be best probed by observations at soft X-ray energies, which require spaceborne observatories, or using ground based mm-observations using the Sunyaev-Zeldovitch (SZ) effect.

Ongoing research projects in the group include:

Studies of the role of the hot galactic atmospheres and accreting supermassive black holes in galaxy evolution. We use proprietary and public multi-wavelength, mostly X-ray and radio, data to study nearby early-type galaxies and test various predictions of the so-called “precipitation” and black hole feedback models, and compare our data with state of the art numerical simulations.

Determine the dynamics, thermodynamics, and the chemical composition of the hot plasma by using multi-wavelength X-ray, SZ, and radio observations. We use mostly X-ray observations of cluster outskirts and merging galaxy clusters and complement these data with SZ and radio observations. We also study mock X-ray observations of state-of the-art cosmological simulations with existing and planned high-resolution X-ray observatories. Our group is involved in the scientific preparations for the Athena mission.

Use of machine learning to study the evolution of galaxies, clusters of galaxies, and the large scale structure of the Universe. We are also looking forward to observations of the evolution of the earliest massive galaxies and their central black holes using the James Webb Space Telescope (JWST).

Selected Publications and Contributions

Extinction biases quasar luminosity distances determined from quasar UV and X-ray flux measurements (adsabs)
Zajaček M., Czerny B., Khadka N., Prince R., Panda S., Martínez-Aldama M. L., Ratra, B., May 2023, submitted to MNRAS.

Particle-in-cell simulations of electron-positron cyclotron maser forming pulsar radio zebras (adsabs)
Labaj, M., Benáček, J., Karlický, M., April 2023, submitted to A&A.

Ram-pressure stripped radio tail and two ULXs in the spiral galaxy HCG 97b (adsabs)
Hu D., Zajaček M., Werner N., Grossová R., Jáchym P., Roberts I. D., Ignesti A., Kenney J. D. P., Plšek T., Breuer J-P., Shimwell T., Tasse C., April 2023, submitted to MNRAS.

Cavity DEtection Tool (CADET): Pipeline for automatic detection of X-ray cavities in hot galactic and cluster atmospheres (adsabs)
Plšek T., Werner N., Topinka M., Simionescu A., April 2023, submitted to MNRAS.

A multifrequency characterization of the extragalactic hard X-ray sky. Presenting the second release of the Turin-SyCAT (adsabs)
Kosiba M., Peña-Herazo H.A., Massaro F., Masetti N., Paggi A., Chavushyan V., Bottacini E., Werner N., February 2023, submitted to MNRAS.

Radio Emission of Nearby Early-type Galaxies in the Low and Very Low Radio Luminosity Range (adsabs)
Wójtowicz A., Stawarz Ł., Cheung C. C., Werner N., Rudka D., February 2023, ApJ, 944, 195.

Detection of a Superluminous Spiral Galaxy in the Heart of a Massive Galaxy Cluster (adsabs)
Bogdán Á., Lovisari L., Ogle P., Kovács O. E., Jarrett T., Jones C., Forman W. R., Lanz L., May 2022, ApJ, 930, 138.

Microscopic black holes as probes for quantum gravity (adsabs)
S. Kováčik, 2022, eprint arXiv:2203.12332

Eigenvalue-flipping algorithm for matrix Monte Carlo (adsabs)
S. Kováčik, J. Tekel, 2022, Journal of High Energy Physics, Volume 2022, Issue 04, article id. 149

Consistency study of high- and low-accreting Mg II quasars: no significant effect of the Fe II to Mg II flux ratio on the radius-luminosity relation dispersion (adsabs)
Khadka, Narayan; Zajaček, Michal; Panda, Swayamtrupta; Martínez-Aldama, Mary Loli; Ratra, Bharat. September 2022, MNRAS, Volume 515, Issue 3.

Standardizing reverberation-measured C IV time-lag quasars, and using them with standardized Mg II quasars to constrain cosmological parameters (adsabs)
Cao, Shulei; Zajaček, Michal; Panda, Swayamtrupta; Martínez-Aldama, Mary Loli; Czerny, Bożena; Ratra, Bharat. eprint arXiv:2205.15552

Wavelength-resolved Reverberation Mapping of quasar CTSC30.10: Dissecting MgII and FeII emission regions (adsabs)
Prince, Raj; Zajaček, Michal; Czerny, Bożena; Trzcionkowski, P.; Bronikowski, M.; Figaredo, C. S.; Panda, S.; Martinez-Aldama, M. L.; Hryniewicz, K.; Jaiswal, V. K.; Śniegowska, M.; Naddaf, M.; Bilicki, M.; Haas, M.; Sarna, M. J.; Karas, V.; Olejak, A.; Przyłuski, R.; Rałowski, M.; Udalski, A.; Sefako, R. R.; Genade, A.; Worters, H. L. eprint arXiv:2201.11062.

Electromagnetic signatures of strong-field gravity from accreting black-holes (adsabs)
Karas, Vladimír ; Zajaček, Michal; Kunneriath, Devaky ; Dovčiak, Michal. Advances in Space Research, Volume 69, Issue 1, p. 448-466.

Discovery of inverse-Compton X-ray emission and robust estimation of magnetic field in a galaxy group (adsabs)
Mernier, F. ; Werner, N. ; Bagchi, J. ; Gendron-Marsolais, M. -L. ; Gopal-Krishna ; Guainazzi, M. ; Richard-Laferrière, A. ; Shimwell, T. W. ; Simionescu, A. eprint arXiv:2207.10092

Geant4 simulation of the residual background in the ATHENA Wide Field Imager from protons deflected by the Charged Particle Diverter (adsabs)
Galgóczi, Gábor ; Breuer, Jean-Paul ; Fioretti, Valentina ; Zlámal, Jakub ; Werner, Norbert; Čalkovský, Vojtěch ; Boudin, Nathalie ; Ferreira, Ivo ; Guainazzi, Matteo ; von Kienlin, Andreas ; Lotti, Simone ; Mineo, Teresa ; Molendi, Silvano ; Perinati, Emanuele. eprint arXiv:2207.06864

Quick Ultra-VIolet Kilonova surveyor (QUVIK) (adsabs)
Werner, N. ; Řípa, J. ; Münz, F. ; Hroch, F. ; Jelínek, M. ; Krtička, J. ; Zajaček, M.; Topinka, M. ; Dániel, V. ; Gromeš, J. ; Václavík, J. ; Steiger, L. ; Lédl, V. ; Seginak, J. ; Benáček, J. ; Budaj, J. ; Faltová, N. ; Gális, R. ; Jadlovský, D. ; Janík, J. ; Kajan, M. ; Karas, V. ; Korčáková, D. ; Kosiba, M. ; Krtičková, I. ; Kubát, J. ; Kubátová, B. ; Kurfürst, P. ; Labaj, M. ; Mikulášek, Z. ; Pál, A. ; Paunzen, E. ; Piecka, M. ; Prišegen, M. ; Ramezani, T. ; Skarka, M. ; Szász, G. ; Thöne, C. ; Zejda, M. eprint arXiv:2207.05485

Athena charged particle diverter simulations: effects of micro-roughness on proton scattering using Geant4 (adsabs)
Breuer, Jean-Paul ; Galgóczi, Gábor ; Fioretti, Valentina ; Zlámal, Jakub ; Liška, Petr ; Werner, Norbert ; Santin, Giovanni ; Boudin, Nathalie ; Ferreira, Ivo ; Guainazzi, Matteo ; von Kienlin, Andreas ; Lotti, Simone ; Mineo, Teresa ; Molendi, Silvano ; Perinati, Emanuele

The cycle of metals in the infalling elliptical galaxy NGC 1404 (adsabs)
Mernier, F. ; Werner, N. ; Su, Y. ; Pinto, C. ; Grossová, R. ; Simionescu, A. ; Iodice, E. ; Sarzi, M. ; Görgei, A. Monthly Notices of the Royal Astronomical Society, Volume 511, Issue 3, pp.3159-3178

The relation between accretion rate and jet power in early-type galaxies with thermally unstable hot atmospheres (adsabs)
Plšek T., Werner N., Grossová R., Topinka M., Simionescu A., Allen S.W., 2022, MNRAS, 517, 3682.

Hawking-radiation recoil of microscopic black holes (adsabs)
Kováčik, Samuel. 2021, Physics of the Dark Universe Vol. 34, Pgs. 100906

Exploring Gravitationally-Lensed z > 6 X-ray AGN Behind the RELICS clusters (adsabs)
Bogdan, Akos; Kovacs, Orsolya E.; Jones, Christine; Forman, William R.; Kraft, Ralph P.; Strait, Victoria; Coe, Dan; Bradac, Marusa. 2021 arXiv e-prints, Pgs. arXiv:2111.03669

Enhanced Doppler Beaming for Dust-enshrouded Objects and Pulsars in the Galactic Center (adsabs)
Zajaček, Michal. 2021, The Astrophysical Journal, Vol. 915, Num. 2, Pgs. 111

Stellar Transits across a Magnetized Accretion Torus as a Mechanism for Plasmoid Ejection (adsabs)
Suková, Petra; Zajaček, Michal; Witzany, Vojtěch; Karas, Vladimír. 2021, The Astrophysical Journal, Vol. 917, Num. 1, Pgs. 43

The Apparent Tail of the Galactic Center Object G2/DSO (adsabs)
Peißker, Florian; Zajaček, Michal; Eckart, Andreas; Ali, Basel; Karas, Vladimír; Sabha, Nadeen B.; Grellmann, Rebekka; Labadie, Lucas; Shahzamanian, Banafsheh. 2021, The Astrophysical Journal, Vol. 923, Num. 1, Pgs. 69

Very Large Array Radio Study of a Sample of Nearby X-ray and Optically Bright Early-Type Galaxies (arXiv)
Grossová, R.; Werner, N.; Massaro, F.; Lakhchaura, K.; Plšek, T.; Gabányi, K.; Rajpurohit, K.; Canning, R.E.A.; Nulsen, P.; O’Sullivan, E.; Allen, S.W.; Fabian A. The Astrophysical Journal Supplement Series, 2022, Volume 258, Issue 2, id.30, 40 pp.

Ultradiffuse Galaxies in the Coma Cluster: Probing Their Origin and AGN Occupation Fraction (adsabs)
Kovács O.E., Bogdán Á., Canning R.E.A., August 2020, ApJ, 898, 164.

Multiwavelength classification of X-ray selected galaxy cluster candidates using convolutional neural networks (adsabs)
Kosiba M., Lieu M., Altieri B., Clerc N., Faccioli L., Kendrew S., Valtchanov I., Sadibekova T., Pierre M., Hroch F., Werner N., Burget L., Garrel C., Koulouridis E., Gaynullina E., Molham M., Ramos-Ceja M.E., Khalikova A., August 2020, MNRAS, 496, 4141.

The mergers in Abell 2256: displaced gas and its connection to the radio-emitting plasma (arXiv, PDF, Supplement)
Breuer, J. P.; Werner, N.; Mernier, F.; Mroczkowski, T.; Simionescu, A.; Clarke, T. E.; ZuHone, J. A.; Di Mascolo, L., MNRAS, Volume 495, Issue 4, July 2020, Pages 5014–5026

Hot gaseous atmospheres of rotating galaxies observed with XMM-Newton (adsabs, PDF)
Juráňová, A.; Werner, N.; Nulsen, P. E. J.; Gaspari, M.; Lakhchaura, K.; Canning, R. E. A.; Donahue, M.; Hroch, F.; Voit, G. M., 2020, Monthly Notices of the Royal Astronomical Society, Vol. 499, Num. 4, Pgs. 5163-5174

Powerful AGN jets and unbalanced cooling in the hot atmosphere of IC 4296 (adsabs)
Grossová R., Werner N., Rajpurohit K., Mernier F., Lakhchaura K., Gabányi K., Canning R.E.A., Nulsen, P., Massaro, F., Sun, M., Connor, T., King, A., Allen, S. W., Frisbie, R. L. S., Donahue, M., Fabian, A. C., 2019, MNRAS, 488, 1917.

Studying the Universe with SmallSats

GRBAlpha and VZLUSAT-2

Among the most important breakthroughs of the past years is the detection of gravitational waves by the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo. In particular, the recent detection of the short gamma-ray burst GRB170817A associated with the gravitational wave signal GW170817 and produced by a binary neutron star merger, marks a milestone in multi-messenger astrophysics and highlights the importance of the efforts to search for electromagnetic counterparts to gravitational wave sources with space-borne instruments. Modern space observatories monitoring GRBs grew into several hundred million Euro missions. However, miniaturization recently opened new opportunities to monitor and localize GRBs with CubeSats (nano-satellites), which are affordable also for small countries and universities. Our group is involved in the HERMES-SP project and the CAMELOT initiative, including two in-orbit demonstration missions, GRBAlpha and VZLUSAT-2.

GRBAlpha has been successfully operating in orbit since March 2021 and has detected several gamma-ray bursts, see the list of transients detected by GRBAlpha. VZLUSAT-2 was successfully launched in January 2022 and has detected several gamma-ray bursts and solar flares, see the list of transients detected by VZLUSAT-2. Our research group is leading the data analysis and the scientific exploitation of the GRB detectors on these missions.


Our research group has recently initiated a proposal of a UV space telescope on a ∼80kg micro-satellite with a moderately fast repointing capability and a near real-time alert communication system. The mission, which has recently been approved for Phase 0, A, and B1 study shall measure the brightness evolution of kilonovae, resulting from the mergers of neutron stars in the near-UV band and thus it shall distinguish between different explosion scenarios. Between the observations of transient sources, the satellite shall perform observations of other targets of interest. The project is lead by the Czech Aerospace Research Centre VZLU, which is also responsible for the platform design. Our research group, together with a broader community of mostly Czech astrophysicists, leads the scientific preparations, including the definition of the scientific objectives and requirements. The Research Centre for Special Optics and Optoelectronic Systems TOPTEC is responsible for the telescope design. PEKASAT is responsible for the design of the communication solutions, ground station, and mission operation centre.

Our group also hopes to be a bridge between astrophysics and theoretical physics, exploring exotic phenomena such as the quantum structure of space and microscopic black-holes.

Selected publications about CubeSats and SmallSats

Checkout lists of transients detected by GRBAlpha and VZLUSAT-2.

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation (adsabs)
Thomas, M., Trenti, M., Sanna, A., Campana, R., Ghirlanda, G., Řípa, J., Burderi, L., Fiore, F., Evangelista, Y., Amati, L., Barraclough, S., Auchettl, K., del Castillo, M. O., Chapman, A., Citossi, M., Colagrossi, A., Dilillo, G., Deiosso, N., Demenev, E., Longo, F., Marino, A., McRobbie, J., Mearns, R., Melandri, A., Riggio, A., Di Salvo, T., Puccetti, S., Topinka, M., 2023, Publications of the Astronomical Society of Australia, 40, e008

Science with a small two-band UV-photometry mission I: Mission description and follow-up observations of stellar transients (adsabs)
Werner, N., Řípa, J., Thöne, C., Münz, F., Kurfürst, P., Jelínek, M., Hroch, F., Benáček, J., Topinka, M., Lukes-Gerakopoulos, G., Zajaček, M., Labaj, M., Prišegen, M., Krtička, J., Merc, J., Pál, A., Pejcha, O., Dániel, V., Jon, J., Šošovička, R., Gromeš, J., Václavík, J., Steiger, L., Segiňák, J., Behar, E., Tarem, S., Salh, J., Reich, O., Ben-Ami, S., Barschke, M. F., Berge, D., Tohuvavohu, A., Sivanandam, S., Bulla, M., Popov, S., Chang, H.-K., 2023, submitted to Space Science Reviews

Science with a small two-band UV-photometry mission II: Observations of stars and stellar systems (adsabs)
Krtička, J., Benáček, J., Budaj, J., Korčáková, D., Pál, A., Piecka, M., Zejda, M., Bakış, V., Brož, M., Chang, H.-K., Faltová, N., Gális, R., Jadlovský, D., Janík, J., Kára, J., Kolář, J., Krtičková, I., Kubát, J., Kubátová, B., Kurfürst, P., Labaj, M., Merc, J., Mikulášek, Z., Münz, F., Paunzen, E., Prišegen, M., Ramezani, T., Rievajová, T., Řípa, J., Schmidtobreick, L., Skarka, M., Szász, G., Weiss, W., Werner, N., 2023, submitted to Space Science Reviews

Science with a small two-band UV-photometry mission III: Active Galactic Nuclei and nuclear transients (adsabs)
Zajaček, M., Czerny, B., Jaiswal, V. K., Štolc, M., Karas, V., Pasham, D. R., Śniegowska, M., Witzany, V., Suková, P., Münz, F., Werner, N., Řípa, J., Merc, J., Labaj, M., Kurfürst, P., 2023, submitted to Space Science Reviews

GRBAlpha: the smallest astrophysical space observatory - Part 1: Detector design, system description and satellite operations (adsabs)
A. Pál, M. Ohno, L. Mészáros, N. Werner, J. Řípa, B. Csák, M. Dafčíková, M. Frajt, Y. Fukazawa, P. Hanák, J. Hudec, N. Husáriková, J. Kapuš, M. Kasal, M. Kolář, M. Koleda, R. Laszlo, P. Lipovský, T. Mizuno, F. Münz, K. Nakazawa, M. Rezenov, M. Šmelko, H. Takahashi, M. Topinka, T. Urbanec, J-P. Breuer, T. Bozóki, G. Dálya, T. Enoto, Z. Frei, G. Friss, G. Galgóczi, F. Hroch, Y. Ichinohe, K. Kapás, L. L. Kiss, H. Matake, H. Odaka, H. Poon, A. Povalač, J. Takátsy, K. Torigoe, N. Uchida, Y. Uchida, 2023, Astronomy & Astrophysics, 677, id.A40

The peak-flux of GRB 221009A measured with GRBAlpha (adsabs)
J. Řípa, H. Takahashi, Y. Fukazawa, N. Werner, F. Munz, A. Pal, M. Ohno, M. Dafcikova, L. Meszaros, B. Csak, N. Husarikova, M. Kolar, G. Galgoczi, J-P. Breuer, F. Hroch, J. Hudec, J. Kapus, M. Frajt, M. Rezenov, R. Laszlo, M. Koleda, M. Smelko, P. Hanak, P. Lipovsky, T. Urbanec, M. Kasal, A. Povalac, Y. Uchida, H. Poon, H. Matake, K. Nakazawa, N. Uchida, T. Bozoki, G. Dalya, T. Enoto, Z. Frei, G. Friss, Y. Ichinohe, K. Kapas, L. L. Kiss, T. Mizuno, H. Odaka, J. Takatsy, M. Topinka, K. Torigoe, 2023, Astronomy & Astrophysics, 677, id.L2

Early results from GRBAlpha and VZLUSAT-2 (adsabs)
J. Ripa, A. Pal, M. Ohno, N. Werner, L. Meszaros, B. Csak, M. Dafcikova, V. Daniel, J. Dudas, M. Frajt, P. Hanak, J. Hudec, M. Junas, J. Kapus, M. Kasal, M. Koleda, R. Laszlo, P. Lipovsky, F. Munz, M. Rezenov, M. Smelko, P. Svoboda, H. Takahashi, M. Topinka, T. Urbanec, J-P. Breuer, T. Enoto, Z. Frei, Y. Fukazawa, G. Galgoczi, F. Hroch, Y. Ichinohe, L. Kiss, H. Matake, T. Mizuno, K. Nakazawa, H. Odaka, H. Poon, N. Uchida, Y. Uchida, January 2022, eprint arXiv:2207.03272

Detection of Low-Energy X-rays Using YSO Scintillation Crystal Arrays for GRB Experiments (adsabs)
Kim, Minbin; Ripa, Jakub; Park, Il H.; Bogomolov, Vitaly; Brandt, Søren; Budtz-Jørgensen, Carl; Castro-Tirado, Alberto J.; Chang, Sheng-Hsiung; Chang, Yenyun; Chen, Chia Ray; Chen, C. -W.; Chen, Pisin; Connell, Paul; Eyles, Chris; Gaikov, Georgii; Hong, Gihan; Huang, Jian Jung; Huang, Ming-Huey Alfred; Jeong, Soomin; Kim, Jieun; Lee, Jik; Lim, Heuijin; Lin, Chih-Yang; Liu, Tsung-Che; Nam, Jiwoo; Panasyuk, Mikhail; Petrov, Vasily; Reglero, Victor; Rodrigo, Juana M.; Svertilov, Sergey; Vedenkin, Nikolay; Wang, Ming Zu; Yashin, Ivan. 2021, Universe, Vol. 7, Num. 11, Pgs. 396

Distributed Architectures and Constellations for γ-ray Burst Science (adsabs)
Fiore, Fabrizio ; Werner, Norbert ; Behar, Ehud. Galaxies, vol. 9, issue 4, p. 120

GRBAlpha: a 1U CubeSat mission for validating timing-based gamma-ray burst localization (PDF)
Pál, A., Ohno, M., Mészáros, L., Werner, N., Ripa, J., Frajt, M., Hirade, N., Hudec, J., Kapuš, J., Koleda, M., Laszlo, R., Lipovský, P., Matake, H., Å melko, M., Uchida, N., Csák, B., Enoto, T., Frei, Z., Fukazawa, Y., Galgóczi, G., Hirose, K., Hisadomi, S., Ichinohe, Y., Kiss, L. L., Mizuno, T., Nakazawa, K., Odaka, H., Takahashi, H., & Torigoe, K. 2020, Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11444, 114444V

Simulations of expected signal and background of gamma-ray sources by large field-of-view detectors aboard CubeSats (PDF)
Galgóczi, G., Řípa, J., Campana, R., Werner, N., Pál, A., Ohno, M., Mészáros, L., Mizuno, T., Tarcai, N., Torigoe, K., Uchida, N., Fukazawa, Y., Takahashi, H., Nakazawa, K., Hirade, N., Hirose, K., Hisadomi, S., Enoto, T., Odaka, H., Ichinohe, Y., Frei, Z., & Kiss, L. 2021, Journal of Astronomical Telescopes, Instruments, and Systems, 7, 028004

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Monitoring the high-energy sky with small satellites
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2022 June 1-3


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High Energy Astrophysics Group
Department of Theoretical Physics and Astrophysics

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