My thoughts on what the Hubble tension really is, based on George Efstathiou’s “To H0 or not to H0?“, arXiv:2103.08723.
This week’s entry features a new proposal by Ed Witten for hunting Planet 9, a study on signatures of scattering between dark energy and visible matter in cosmological observations, and new constraints on light dark matter produced from primordial black hole evaporation. As usual, comments are welcome, and hope you enjoy!
With a week of delay due to Italian bureaucracy-induced commitments, my Week 17 summaries are now out. There is a new entry in terms of topics covered, i.e. the thorny issue of naturalness in particle physics and cosmology (besides two papers covering limits on the duration of inflation, and independent inferences of the baryon energy density from Planck). As always, comments are very welcome!
A quick note to inform regular readers that my Week 17 review will likely be delayed. The reason is an important upcoming deadline for applying for the so-called Abilitazione Scientifica Nazionale (ASN), regulated by the Ministry of Education, University, and Research of Italy (MIUR). The ASN can be roughly translated as “National Scientific Habilitation”. It is qualification which is required to apply for permanent academic positions in Italy (you can read more here). Needless to say this application will be keeping me (and several other Italian researchers - many abroad) busy for the next few days…
This week’s entry discusses two papers on shadows (one in relation to superradiance, and one in relation to naked singularities), and one paper addressing the important question of how model-independent BAO measurements are. Following the discussion of the third paper, I have included a long-ish bonus discussion on what my opinion is on this whole BAO model-independence business (some readers might find the discussion provocative, if so that was not my intention). Enjoy!
This week’s entry focuses on observational tests of a specific class of string inflationary models (which allow to set limits on the fundamental microscopic string parameters), observational tests of naked singularity spacetimes from their shadows and the continuum spectrum emitted from accretion disks, and finally a study addressing the interesting question of what was the maximum initial temperature of the Universe in the radiation domination epoch. Happy Easter to those readers who celebrate it!
This week’s entry features a new ACT CMB lensing cross BOSS CMASS galaxies cross-correlation measurement implementing a new tSZ-cleaning procedure, a new update on the H0 tension and in particular how fifth forces could lower the TRGB-calibrated measurement (besides the usual Cepheid-calibrated one), and finally the return of black hole shadows (in asymptotically de Sitter spacetime). Enjoy and stay safe!
For a change, no H0 tension in this week’s entry (although I briefly touch on a new H0 measurement in paper 1)! This week I cover a new way to measure cosmological distances, a new dark matter candidate from an alternative to black holes, and the first calculation of how the neutrino Casimir force depends on the Dirac vs Majorana nature of neutrinos. Enjoy, and stay at home!
The past few weeks have clearly been very successful as far as prizes go :) Just today I found out that I am one of the recipients of the 2019 IOP Publishing Outstanding Reviewer Award for the British journal Classical and Quantum Gravity (CQG)!
This week’s entry is dedicated to the H0 tension and attempts to solve the latter through early dark energy (possibly going beyond General Relativity), as well as to how a mysterious phenomenon known as skyquakes could be connected to an exotic model of dark matter known as axion quark nuggets. I hope this post will provide you a bit of entertainment (hopefully at home) in this time of uncertainty due to COVID-19.
