Tootfinder

Cosmic Strings in Multi-Step Symmetry Breaking
Akifumi Chitose, Masahiro Ibe, Satoshi Shirai, Yaxuan Wen
https://arxiv.org/abs/2506.15194 https://

Cosmic Strings in Multi-Step Symmetry Breaking
We investigate cosmic strings arising from a hierarchical gauge symmetry breaking sequence, $\mathrm{SU}(2) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1)' \rightarrow \text{Nothing}$. This pattern gives rise to two distinct classes of cosmic strings: light, stable strings formed at a later stage, and heavy, metastable strings originating from an earlier stage. Our focus is on the heavy strings, which may decay either before or after the final $\ma…

Went to see a Hoopla improv show at The Bell, a mix of half a dozen different groups doing different thin
gs. "Shuffle improv" were basing their scenes on a shuffled playlist built by the audience on the way in
and an interesting format from a improv-as-a-second-language group chatting about their experiences in a
foreign land and basing their scenes off it. The group called "twelve people" only had six but were good
chaotic fun.
Lots of stuff about cooking and food.
I found myself pondering optimum size for an improve group. In general the larger groups seemed more fun to me, with the exception of three-person "burn the script" who did excellent work. More than eight wouldn't fit in the tiny stage at that venue. In rehearsal I like to have the group split in half and perform for each other. Hard to do that with fewer than six. Still up in the air if our group will get off the ground or not. More people does mean more calendar clashes even if it makes for a cheaper-per-person room hire.
Everyone has instagram pages, which are no use to me. Won't link or visit there. Interesting that nobody has a Twitter profile any more and of course nobody seems to have just a damned website which still strikes me as madness. Imagine not wanting to own your own space on the web?
#improv #london

Procedures for Constraining Robotic Fiber Positioning for Highly Multiplexed Spectroscopic Surveys: The Case of FPS for SDSS-V
Ilija Medan, Tom Dwelly, Kevin R. Covey, Eleonora Zari, Michael R. Blanton, Joleen K. Carlberg, S. Drew Chojnowski, Alexander Ji, Yue Shen, John Donor, Jos\'e S\'anchez-Gallego, Sean Morrison, H\'ector J. Ibarra-Medel, Conor Sayres, Keivan G. Stassun

Procedures for Constraining Robotic Fiber Positioning for Highly Multiplexed Spectroscopic Surveys: The Case of FPS for SDSS-V
One crucial aspect of planning any large scale astronomical survey is constructing an observing strategy that maximizes reduced data quality. This is especially important for surveys that are rather heterogeneous and broad-ranging in their science goals. The Sloan Digital Sky Survey V (SDSS-V), which now utilizes the Focal Plane System (FPS) to robotically place fibers that feed the spectrographs, certainly meets these criteria. The addition of the FPS facilities an increase in survey efficienc…

Not-quite-primordial black holes
Wenzer Qin, Soubhik Kumar, Priyamvada Natarajan, Neal Weiner
https://arxiv.org/abs/2506.13858 https://

Not-quite-primordial black holes
We propose a new mechanism for the formation of seeds of supermassive black holes at early cosmic epochs. Enhanced density fluctuations with amplitudes that are not large enough to form primordial black holes post-inflation can still lead to collapsed dark matter halos at very early times. For halos forming prior to $1+z \approx 200$, the Cosmic Microwave Background (CMB) is energetic enough to suppress the formation of molecular hydrogen, hence preventing cooling and fragmentation, as a conseq…

Known as “white” asbestos,
chrysotile asbestos is banned in more than 50 countries
for its link to lung cancer and mesothelioma,
a cancer that forms in the lining of internal organs.
White asbestos, however, has been imported for use in the United States for roofing materials, textiles and cement as well as gaskets, clutches, brake pads and other automotive parts.
It is also used in chlorine manufacturing.
Last year the Environmental Protection Agency, u…

E.P.A. Plans to Reconsider a Ban on Cancer-Causing Asbestos
The Trump administration’s move sets back a decades-long effort to end the use of the material, which is widely banned in other countries.

With the #AAS246 presser number 3 came the press releases https://www.stsci.edu/contents/news-releases/2025/news-2025-018 (Moons of Uranus Surprise Scientists in NASA Hubble Study) and https://webbtelescope.org/contents/news-releases/2025/news-2025-125 (Frigid Exoplanet in Strange Orbit Imaged by NASA's Webb) and the paper "Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system" already covered in https://scicomm.xyz/@cosmos4u/114660217108691128 with the press release https://www.tcd.ie/news_events/top-stories/featured/silicate-clouds-discovered-in-atmosphere-of-distant-exoplanet/ (Silicate clouds discovered in atmosphere of distant exoplanet).

Do Cosmic String Segments Emit Gravitational Waves?
Akifumi Chitose, Masahiro Ibe, Shunsuke Neda, Satoshi Shirai
https://arxiv.org/abs/2507.12386 https://

Do Cosmic String Segments Emit Gravitational Waves?
Cosmic strings are predicted in various extensions of the Standard Model, including grand unified theories. Depending on the symmetry-breaking pattern, they can be either topologically stable or metastable. Intriguingly, metastable strings have been proposed as a possible origin of the gravitational wave (GW) background observed by recent pulsar timing array experiments. When metastable strings decay, they fragment into segments with monopoles and antimonopoles attached at their endpoints. The …

Observation of the Shadows of the Moon and Sun Using the Pierre Auger Observatory at an Average Energy of $7\times10^{17}\,$eV
Katar\'ina \v{S}imkov\'a (for the Pierre Auger Collaboration)
https://arxiv.org/abs/2507.08582

Observation of the Shadows of the Moon and Sun Using the Pierre Auger Observatory at an Average Energy of $7\times10^{17}\,$eV
The interaction of cosmic rays with celestial bodies such as the Moon or the Sun produces a shadow in the arrival direction distribution of the cosmic rays reaching the Earth. Such deficits from an isotropic flux have been observed by astroparticle observatories below energies of $10^{15}\,$eV. Above this energy, measurements were limited due to the low number of events as a result of the steeply falling cosmic-ray flux with energy. With more than 10.6 million events recorded during 20 years of…

More Masana slides about the geography and road network of relevance for the 2026 Total #SolarEclipse - beware of shadows and traffic. 11/n

Calibrating baryonic effects in cosmic shear with external data in the LSST era
Amy Wayland, David Alonso, Matteo Zennaro
https://arxiv.org/abs/2506.11943 …

Calibrating baryonic effects in cosmic shear with external data in the LSST era
Cosmological constraints derived from weak lensing (WL) surveys are limited by baryonic effects, which suppress the non-linear matter power spectrum on small scales. By combining WL measurements with data from external tracers of the gas around massive structures, it is possible to calibrate baryonic effects and, therefore, obtain more precise cosmological constraints. In this study, we generate mock data for a Stage-IV weak lensing survey such as the Legacy Survey of Space and Time (LSST), X-r…