Welcome to my webpage!
I'm an Assistant Astronomer ("Astronome Adjoint") at the Institut de Recherche en Astrophysique et Planétologie (IRAP – Toulouse, France).
On these pages you will find more about my activities, research interests, as well as a CV, a list of publications, and other (useful and less useful) things...
Research interests
About 80% of the total baryonic matter of the Universe is in the form of a very hot gas, glowing in X-ray wavelengths, and filling the very large gravitational well of clusters of galaxies. This so-called intra-cluster medium (ICM) contains not only primordial hydrogen and helium, but is rich in heavy elements (O, Mg, Si, S, Ca, Fe, Ni,...). These metals have been created by billions of supernovae within cluster galaxies since the major epoch of star formation (about 10-12 billion years ago), then spread out and accumulated over cosmic time into the ICM. When, where, and how did this chemical enrichment occur? And which types of supernovae are responsible for creating the metals we see today? Using X-ray observatories (e.g. XMM-Newton, Chandra, XRISM), I measure the abundance of these elements in galaxy clusters in order to answer these open questions.
Cas A supernova
(credit: NASA/JPL-Caltech)
Abell 4038
(credit: F.M.)
Hydra A
(credit: Chandra X-ray obs.)
M87
(credit: Chandra X-ray obs.)
Abell 85
(credit: F.M.)
Tycho supernova
(credit: NASA/CXC/Rutgers)
XMM-Newton
(credit: ESA)
Perseus cluster
(credit: NASA/CXC/IoA)
Résumé
Born in Brussels (Belgium), 27 June 1989
Languages: French (native), English (fluent), Dutch (intermediate)
Academic positions
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2025-now - Astronome-adjoint (Assistant astronomer) - IRAP, Toulouse (France)
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2022-2024 - XRISM support scientist - NASA/GSFC, University of Maryland (USA)
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2019-2022 - Research Fellow - ESA/ESTEC (The Netherlands)
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2017-2019 - Postdoc - MTA/Eötvos University (Hungary)
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2017-2017 - Postdoc - Leiden University (The Netherlands)
Education
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2013-2017 - PhD - High-energy Astrophysics, Leiden University/SRON (The Netherlands)
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2010-2012 - MSc - Space Sciences, University of Liège (Belgium)
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2007-2010 - BSc - Physics, Université Libre de Bruxelles (Belgium)
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2001-2007 - High school - Latin-Mathematics, Lycée Émile Jacqmain, Brussels (Belgium)
Publications
First author:
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- Mernier, F., Su, Y., Markevitch, M., Zhang, C., Simionescu, A., Rasia, E., Lin, S.-C., Zhuravleva, I., Sarkar, A., Kraft, R., Ogorzalek, A., Ayromlou, M., Forman, W. R., Jones, C., Bregman, J. N., Ettori, S., Dolag, K., Biffi, V., Churazov, E., Sun, M., ZuHone, J., Bogdán, Á., Khabibullin, I. I., Werner, N., Truong, N., Chakraborty, P., Walker, S. A., Vogelsberger, M., Pillepich, A., Mirakhor, Mohammad S.
Exploring chemical enrichment of the intracluster medium with the Line Emission Mapper (White Paper)
2023, arXiv:2310.04499 -
- Mernier, F., Werner, N., Bagchi, J., Gendron-Marsolais, M.-L., Gopal-Krishna, Guainazzi, M., Richard-Laferrière, A., Shimwell, T. W., Simionescu, A.
Discovery of inverse-Compton X-ray emission and estimate of the volume-averaged magnetic field in a galaxy group
2023, MNRAS, 524, 4939 -
- Mernier, F., Werner, N., Su, Y., Pinto, C., Grossová, R., Simionescu, A., Iodice, E., Sarzi, M., Görgei, A.
The cycle of metals in the infalling elliptical galaxy NGC 1404
2022, MNRAS, 511, 3159 -
- Mernier, F., Cucchetti, E., Tornatore, L., Biffi, V., Pointecouteau, E., Clerc, N., Peille, P., Rasia, E., Barret, D., Borgani, S., Bulbul, E., Dauser, T., Dolag, K., Ettori, S., Gaspari, M., Pajot, F., Roncarelli, M., Wilms, J., Noûs, C.
Constraining the origin and models of chemical enrichment in galaxy clusters using the Athena X-IFU
2020, A&A, 642, A90 -
- Mernier, F., Werner, N., Lakhchaura, K., de Plaa, J., Gu. L, Kaastra, J. S., Mao, J., Simionescu, A., Urdampilleta, I.
How do atomic code uncertainties affect abundance measurements in the intracluster medium?
2020, Astron. Nachr., 341, 203 -
- Mernier, F., Werner, N., Bagchi, J., Simionescu, A., Böhringer, H., Allen, S. W., Jacob, J.
Magnetic fields and extraordinarily bright radio emission in the X-ray faint galaxy group MRC 0116+111
2019, MNRAS, 486, 5430 -
- Mernier, F., Biffi, V., Medvedev, P., Simionescu, A., Ettori, S., Werner, N., Kaastra, J. S., de Plaa, J., Gu, L.
Enrichment of the Hot Intracluster Medium: Observations
2018, Space Sci Rev, 214, 129 -
- Mernier, F., Werner, N., de Plaa, J., Kaastra, J. S., Raassen, A. J. J., Gu, L., Mao, J., Urdampilleta, I., Simionescu, A.
Solar chemical composition in the hot gas of cool-core ellipticals, groups, and clusters of galaxies
2018, MNRAS: Letters, 480, L95 -
- Mernier, F., de Plaa, J., Werner, N., Kaastra, J. S., Raassen, A. J. J., Gu, L., Mao, J., Urdampilleta, I., Truong, N., Simionescu, A.
Mass-invariance of the iron enrichment in the hot haloes of massive ellipticals, groups, and clusters of galaxies
2018, MNRAS: Letters, 478, L116 -
- Mernier, F., de Plaa, J., Kaastra, J. S., Zhang, Y.-Y., Akamatsu, H., Gu, L., Kosec, P., Mao, J., Pinto, C., Reiprich, T. H., Sanders, J. S., Simionescu, A., Werner, N.
Radial metal abundance profiles in the intra-cluster medium of cool-core galaxy clusters, groups, and ellipticals
2017, A&A, 603, A80 -
- Mernier, F., de Plaa, J., Pinto, C., Kaastra, J. S., Kosec, P., Zhang, Y.-Y., Mao, J., Werner, N., Pols, O. R., Vink, J.
Origin of central abundances in the hot intra-cluster medium. II. Chemical enrichment and supernova yield models
2016, A&A, 595, A126 -
- Mernier, F., de Plaa, J., Pinto, C., Kaastra, J. S., Kosec, P., Zhang, Y.-Y., Mao, J., Werner, N.
Origin of central abundances in the hot intra-cluster medium. I. Individual and average abundance ratios from XMM-Newton EPIC
2016, A&A, 592, A157 -
- Mernier, F., de Plaa, J., Lovisari, L., Pinto, C., Zhang, Y.-Y., Kaastra, J. S., Werner, N., Simionescu, A.
Abundance and temperature distributions in the hot intra-cluster gas of Abell 4059
2015, A&A, 575, A37 -
- Mernier, F., and Rauw, G.
An XMM-Newton view of the M 17 nebula
2013, NewA, 20, 42
Co-author:
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- See full lists below.
Scripts (etc.)
Here are some of my scripts, routines and tables you may find useful...
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Fits a set of intra-cluster abundances with a combination of supernova yield models. Several models (either SNcc or SNIa) are available and can be updated or created.
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These tables show the relative deviations of a given best-fit parameter (kT, Fe, O/Fe, Mg/Fe, Si/Fe, S/Fe) between the X-ray spectral models "cie" v3.0.5 (in the fitting package SPEX) and "(v)apec" v3.0.9 (in the fitting package XSPEC) expected for a collisionally ionized plasma at various assumed temperatures and metallicities. When you get a best-fit temperature or metal abundance value for your favourite galaxy cluster/group using your favourite spectral code, you can refer to these tables. They will give you an estimate of the current atomic/code-related uncertainties of your best-fit parameter.
- abunfit
/!\ If you use abunfit.py for a publication, please cite:
Mernier, F., de Plaa, J., Pinto, C., et al. 2016b, A&A, 595, A126
/!\ If you use the abundance measurements reported in abunfit/cluster/
for a publication, please cite:
Mernier, F., de Plaa, J., Pinto, C., et al. 2016a, A&A, 592, A157
/!\ If you use the supernova yields reported in abunfit/ for a publication,
please cite the original papers accordingly.
- SPEX (cie) vs. XSPEC (apec) comparison
/!\ If you use or refer to these numbers in a publication, please cite:
Mernier, F., Werner, N., Lakhchaura, K., et al. 2019, Astron. Nachr., 341, 203
PhD thesis
Outreach
Science is for everyone, and thus should be accessible to everyone. We, astronomers, are in general supported by public fundings; therefore it is also our responsibility to “close the loop” by revealing citizens the beauty of the Universe, keeping young (and less young) minds curious, and show the necessity of science in everyday’s life.
Below you will find some slides I presented during outreach events; in particular for the astronomy youth camps "Jeunesse et Science" (Modave, Belgium), for Astronomy on Tap - Budapest, and for Astronomy on Tap - Leiden.
About me (outside astronomy)
Astronomy is great, so are many other activities.
I'm also into music (rock, pop, and/or jazz), and one of my favourite Sunday-afternoon activities is to play piano/keyboards (see my YouTube channel). I'm also into sports: (indoor) football, fencing, sometimes also swimming, biking, or simply running. And of course, always in for deep discussions about politics, society, and philosophy while enjoying a good (preferably Trappist!) beer.
Contact
Institut de Recherche en Astrophysique et Planétologie (IRAP),
9 av. du colonel Roche,
31400 Toulouse (France),
Email: [firstname].[surname]@utoulouse.fr
...where [firstname] is francois
...and [surname] is mernier