Live and recent posts from across the Fediverse tagged #cosmomag, aggregated by home.social.
Gradual building of the magnetic cosmic web (the quantity on display is the magnetic field strength) along a portion of the simulated cosmic web, one slice at a time for 100Mpc/h. ENZO-MHD simulation produced for the scientific case of the Square Kilometer Array.
#COSMOMAG #SimulatedUniverses #astrophysics #astronomy #science
#paperday on #astroph
"Monitoring the power spectrum of magnetic field fluctuations
across the simulated intracluster medium" by PhD student Tommaso Bartalesi, myself et al.
https://arxiv.org/pdf/2609.19307
we discuss how the 3D spectrum of magnetic fields amplified by cluster dynamics change as a function of the position and local dynamics of a cluster of galaxies, simulated at high resolution using ENZO-MHD.
The (simulated) progressive ejection of magnetic fields from galaxies (via galactic winds and/or AGN feedback) into the cosmic web, in a large ENZO cosmological simulation run on LEONARDO at CINECA.
The red colors mark the baryon matter distribution while the green colors mark the magnetic field amplitude, averaged along the line of sight.
Same cosmological model and same dark matter distribution (left) but two differently simulated magnetic field model in the other two panels: a stochastic magnetic field with correlation length=250kpc (centre) or a magnetic field with correlation length 1Mpc (right). The final magnetic fields are similar within halos, while they remain significantly different in more rarefied regions (filaments, voids) .
For the same simulation displayed here on a tomographic scan
https://mastodon.social/@franco_vazza/117228586791104438
this is instead how a fixed slice looks as a function of changes in the initial cosmological or magnetic field parameters
-s05-1.0 : changes in the initial σ8
-B09---B16 changes in the initial magnetic field amplitude (uniform seed field)
-nB=-2.09-2.0 changes in the initial slope of the power-spectrum seed magnetic field.
more details in https://arxiv.org/pdf/2511.22573
#cosmomag #astrophysics #SimulatedUniverses
Continuous scanning through the layers of the dark matter distribution in a simulated 150^3 Megaparsec volume, of the "baseline" (=simple physics) run of our Makitra https://cosmosimfrazza.eu/makitra suite of simulations. The resolution is small (512^3 particles/cells) and yet the intricacy of the web of matter is gorgeous already.
A resolution test in which the same initial uniform magnetic field is evolved using from 100^3 cells (top left) to 800^3 cells (bottom right), i.e. going from 100kpc of resolution to 12,5kpc.
In most of the cosmic volume, i.e. in cosmic voids and filaments, where compression/expansion dominate, the magnetic fields little evolve with resolution. In halos instead, where dynamo switches on if the fluid is turbulent, we don't have a very converged solution.
#cosmomag #astrophysics #physics #science
#paperday by A. Botteon et al. including myself
"The topology of the magnetic field in Abell 2255 out to its virial radius"
https://arxiv.org/pdf/2607.14209
This study uses very deep MeerKAT radio observations of diffuse emission in a famous cluster of galaxies, to try a reconstruction of the magnetic field topology (something you cannot easily know in 3-dimension, of course)
Three models of primordial magnetic field seeds evolving in the same cubic 10 Megaparsec box. The extreme left is for an inflationary-like spectrum (fluctuations correlated on large scales), the middle is for a causal post-inflationary model (fluctuations only on <<Mpc scales), the extreme right is for a uniform magnetic field. Especially in voids, the memory of the seed structure is retained even until at present.
#paperday
"Bridging the mass gap: Diffuse radio emission in GAMA galaxy groups
using EMU and DINGO survey data" by Sai Wagh and collab. including myself.
https://arxiv.org/pdf/2607.12434
It presents the radio analysis of ASKAP-EMU maps of 400 groups in the Gama survey, focusing on the diffuse synchrotron radio emission after the contribution of radio galaxies has been removed - reporting quite a lot of unexpected emission.
#paperday on #astroph
"An SKA-Low RM Grid for constraining the origin of cosmic magnetism" by S. O'Sullivan, myself and others
https://arxiv.org/abs/2606.25096
in one of the many contribution to the Advancing Astrophysics with the SKA II collection of works.
Here we discuss the many directions in which the SKA is going to improve our understanding of cosmic magnetism using its polarisation capabilities, to study the Faraday Rotation effect across the cosmic web
#paperday on #astroph
"Isochrones in primordial magnetic field evolution"
by A. Brandenburg, Cielo, Iarygina & myself
https://arxiv.org/pdf/2606.10863
where we present Pencil simulations of the evolution of different stochastic magnetic field configurations in the early universe, with the goal of finding simple ways to rescale them to the same evolutionary sequence.
(submitted to A&A)
"The Impact of the Magnetised Cosmic Web on Ultra High Energy Cosmic Ray Propagation" by Allegra Firinu, myself and Carmelo Evoli.
We investigated the role of realistic extragalactic magnetic fields in deflecting E>1e18eV cosmic rays, effectively creating "an horizon" beyond which particles cannot reach us, as they are trapped by magnetic fields.
Two cool papers today in #astroph, related to our #COSMOMAG exploration:
https://arxiv.org/pdf/2604.25647
Intergalactic Magnetic Field constraints from detected very high-energy Gamma-Ray Bursts using the Cherenkov Telescope Array Observatory (Keita et al.)
https://arxiv.org/abs/2604.24835 JWST Constraints on Primordial Magnetic Fields (Fairbarn et al)
Both explore the upper and lower limits allowed for primordial fields in the Universe, with different effects.
In other news, since yesterday our project COSMOMAG funded by the #ERC with a Synergy Grant has officially started!
It will last until 2032 at least.
Principal investigators: A. Neronov (APC), C.Caprini (CERN), A. Brandenburg (Nordita), F. Vazza (UNIBO).
Here is the (unofficial) website in the absence of an official one 😅
https://cosmosimfrazza.eu/cosmomag and we even have a professional logo!
I will use the #COSMOMAG hashtag to relate to it in the near future.
Conclusion of a 2-weeks PhD school organised at Nordita (Stockholm) within our newborn #COSMOMAG project. I hope it was a nice closing for the ~30 students who visited us, and who hopefully by now have a more in-depth understanding of the phenomenology of cosmic #magnetism and of its incredible potential to unlock some of the biggest mysteries in the Universe.
One piece of yesterday lectures at Nordita from our #COSMOMAG school: how a discovery during the late stage of M. #Faraday's career turned a failure in optical astronomy into a vertiginous progress for radio astronomy.
"Faraday Rotation" is the most powerful we have to perform magnetic tomography of the Universe and study the 3 dimensional distribution of B in clusters and possibly filaments of galaxies
Todays and yesterday lectures at Nordita for our #COSMOMAG school:
connecting linear and non-linear stages of cosmic structure formation to potential impact of primordial magnetic fields on halo formation and their clustering.
I begun yesterday a full one week every -day teaching at the Winter Astrophysics School at Nordita (Stockholm) about primordial magnetic fields and their evolution, pretty much connected with our incoming #COSMOMAG project. Usually when you prepare lectures, you learn a lot.
My goal is to show the connections between cosmic structure formation and magnetism.
Will the students learn more, or I?
#academia #astrophysics #science
Kickoff of the Nordita Winter School on Cosmological Magnetic Fields we organised within #COSMOMAG in Stockholm, with about 40 international participants (mostly PhD students), which will last 2 intense weeks.
Remarkable quote from lecture one by A. Neronov: "There's nothing wrong with the Universe having magnetic fields" 😅
#COSMOMAG-related Post-Docs in CERN, and Laboratoire de Physique de l’École Normale Supérieure with C. Caprini, with projects related to
- The generation, evolution, and properties of primordial magnetic fields at the electroweak energy scale
- The generation, evolution, and properties of primordial magnetic fields at the QCD energy scale
please share with potentially interested applicants.
DEADLINE 20 January!
#Academic #JobPosting in #astronomy
2 Full-time Post-Doctoral Fellowship at NORDITA (Stockholm) on the theoretical study of the generation of evolution of primordial magnetic fields, under the supervision of A. Brandenburg and within the recently funded ERC Synergy Grant #COSMOMAG
https://su.varbi.com/en/what:job/jobID:887705/where:4/
Deadline to apply: 20 January 2026
#paperday
"Magnetic field spreading from stellar and galactic dynamos into the exterior" by A. Brandenburg, O. Ghosh, myself and A. Neronov
https://arxiv.org/pdf/2512.17770
It is the direct numerical simulation, using the PENCIL code, of how magnetic fields produced by the mean-field dynamo in (very idealised) galaxies distribute over large distances (i.e. potentially into voids).
Big day! Carrying the official announcements of funded #ERC #SynergyGrants, including the one I am part of:
which will study the first micro-seconds (!) of the Universe using magnetic fields (and gravitational waves).
Interesting 6 years ahead!!
https://erc.europa.eu/news-events/news/synergy-grants-2025-examples-projects