Andrea Botteon

#paperday #Extragalactic What determines whether a galaxy can become a jellyfish galaxy? Thanks to new Meerkat data, we now propose that this may be due to a combination of supersonic orbits and interactions with the magnetic field of the galaxy cluster. More at arxiv.org/abs/2602.21821

High-resolution LOFAR HBA image of the tailed radio galaxy (C) in the galaxy cluster MACS J1354.6+7715, observed at 144 MHz. A and B denotes two compact radio sources, while D marks an additional radio source detected in the field. Please see the paper for the full caption.

Composite image of the cluster combining optical, radio, and X-ray data. Please see the paper for the full caption.

Published in #MNRAS: "Wiggling through the ICM: multiresolution radio imaging of a tailed radio galaxy in MACS J1354.6+7715", Gani et al. These are Figs. 1 & 6: please visit academic.oup.com/mnras/articl... to read the paper. @royalastrosoc.bsky.social @academic.oup.com

LoTSS-DR3, by Shimwell+ (w/ many)
We have released the largest collection of data from a radio survey: 13M+ sources detected over 19k deg^2 (88% of the Northern sky). This took ~13k h of @LOFAR observations, ~18 PT of data, and 10+ years of work. Data are public from today
arxiv.org/abs/2602.15949

Screenshot from the frontpage of the Open Journal of Astrophysics, featuring the following article informations. Title reads "Revisiting the Great Attractor: The Local Group's streamline trajectory, cosmic velocity and dynamical fate". Authors list: Richard Stiskalek, Harry Desmond, Stuart McAlpine, Guilhem Lavaux, Jens Jasche, Michael J. Hudson. Summary reads "The study revisits the Great Attractor concept, finding that it doesn't dominate the Local Group's cosmic velocity; multiple structures contribute to the motion, with no single attractor accounting for it". Dated February 17, 2026. Background image featuring an allsky map of the depth of the inferred Classical Great Attractor basin as a function of sky position in Galactic coordinates.

Great paper on the Great Attractor, just published by The Open Journal of Astrophysics

doi.org/10.33232/001...

@ojastro.bsky.social 🧪 #Cosmology #Cosmicflows

and @tonymroczkowski.bsky.social!

A radio relic mimicking a radio halo? by @paola-dominguez.bsky.social+ (w/ @jzuhone.bsky.social @emstar.bsky.social myself+)
This could be the case of MACSJ0018.5+1626, where numerical simulations show that the radio emission could be due to a relic seen face-on
arxiv.org/abs/2602.05050

Radio observations A1775 and A1795, by vanWeeren+ (w/ @cjriseley.bsky.social, @rtimmerman.bsky.social, myself+)
MeerKAT @SKA_Africa recovers the known diffuse emission in both systems. Interestingly, the large-scale halo in A1795 is compatible with a hardonic origin...
arxiv.org/abs/2601.16288

New study of two merging galaxy clusters, by Srikanth+ (w/ myself, @roxycas++)
@LOFAR, GMRT, and @ESA_XMM observations are combined to investigate the nature of the diffuse emission in A773 and A1351.
Congrats to Koushika on her first paper!
arxiv.org/abs/2601.13316

...and of course:

Pick your favorite "dot"

What comes after paper I? Paper II! Still led by @e_derubeis
In the new paper, a more detailed investigation about the origin of the filaments is done by combining LOFAR @astronnl.bsky.social data with new uGMRT and VLA observations at higher frequency
arxiv.org/abs/2512.19471

Paper accepted for publication in @aanda-journal.bsky.social! You can find the accepted version in today's replacements on arXiv (arxiv.org/abs/2509.14348). The only notable update is that we left the merger scenario open, as we are not sure if the clusters are observed pre or post collision

A fresh look at Abell 2163, by Santra+ (including myself)
This is one of the hottest, most massive, and brightest cluster in the sky. New uGMRT band 3 and band 4 data are used to study the giant (among the largest!) radio halo hosted in this merging system
arxiv.org/abs/2511.22124

Check for the wonderful science that @axisprobe.bsky.social would enable in the white book uploaded today in arXiv: arxiv.org/abs/2511.00253
I've participated with a chapter on "X-ray and radio surface brightness edges in the ICM", you can find it in the Galaxies GO Science section (page 69)

News on Abell 754 from @XRISM_jp, by Okabe+ and Omiya+
Combining the gas kinematic from XRISM and WL from Subauru, a new merger scenario is proposed. The "3rd dimension" has been unlocked thanks to XRISM 😀
arxiv.org/abs/2510.16291
arxiv.org/abs/2510.16553

Color rendering of the dark matter particle distribution from a N-body simulation of a LCDM model. Dark matter halos are visible as clumps of different sizes. The color coding follows the mass of the halos, with large halos appearing redder and small halos appearing bluer. The characteristic filamentary structure of the Cosmic Web is striking. Simulation credit: RAMSES. Image credit: S. Colombi.

in the #arXiv

Numerical Cosmology

by Romain Teyssier
arxiv.org/abs/2510.13129 🧪 #Cosmology

I also had two papers come out this month! I worked on the first XRISM results from the Perseus cluster and got time on XRISM to observe A1914, which we discovered was undergoing a line-of-sight merger! 🔭

To conclude, this work adds to the growing effort to investigate nonthermal phenomena outside the denser and well-studied regions of the ICM. Future instruments like @SKAO will likely probe these regions more efficiently. Paper submitted 7/7

What about the uGMRT non-detection? Since diffuse sources in cluster pairs are rare, even spectral limits would help to understand the mechanisms generating the emission. However, the MeerKAT emission is unfortunately too faint to provide a meaningful limit with the uGMRT... 6/7

We compared this extended emission with radio bridges and halos. While its classification is uncertain, its properties align with that expected for a diffuse emission generated in an early stage of the merger 5/7

The radio emission nicely follows the elongation of the X-ray emission from the clusters and intra-cluster bridge, suggesting that it is likely generated as consequence of the cluster-cluster encounter. In-between the clusters, the radio emission is enhanced 4/7

After careful analysis and removal of discrete sources, we confirmed the presence of the extended emission. The large-FoV images show that diffuse emission is present only at the position of the cluster pair in the MeerKAT field, while we have a non-detection with the uGMRT 3/7

The clusters are interacting and are likely observed shortly after pericenter passage. From the MeerKAT images, we noticed "excess" diffuse emission in the intra-cluster region 2/7

New paper alert! We studied a galaxy cluster pair with @SKA_Africa MeerKAT UHF and @NCRA_Outreach uGMRT band 3 data and found diffuse emission between the two clusters! 1/7
arxiv.org/abs/2509.14348

Aaand the paper has been accepted! The accepted version of the paper was posted on arXiv on Aug 19: arxiv.org/abs/2505.05415

Where is the counter lobe? An interesting hypothesis is that it could have been stretched as a consequence of the sloshing in the system, resulting in what is now observed as bridge/arc. See also our recent MeerKAT paper on Ophiuchus (arxiv.org/abs/2504.16158)!

Low frequency observations of the Ophiuchus cluster, by Giacintucci+
The giant fossil lobe is studied in detail. The new data show steep spectrum filamentary structures embedded in the lobe. The lobe extends up to 820 kpc from the cluster center
arxiv.org/abs/2508.20190

.@XRISM_jp obs of the Ophiuchus cluster, by Fujita+
A low velocity dispersion is measured in the inner and outer regions (115 km/s at <25kpc, 186 km/s at 25-50 kpc). The same goes for the bulk velocity (8 km/s vs 104 km/s): is the sloshing at its minimum?
arxiv.org/abs/2507.00126

(w/ @cjriseley.bsky.social, @annalisa-astro.bsky.social, @CStuardi, @FraLoi1)

The magnetic field in A2142, by Pagliotta+
A rotation measure and polarization study is performed with MeerKAT. The magnetic field profile of the ICM is drawn, indicating a central field strength of 9.5 muG at the cluster center.
arxiv.org/abs/2507.00114