My thoughts on what the Hubble tension really is, based on George Efstathiou’s “To H0 or not to H0?“, arXiv:2103.08723.
After disappearing for a week, this week I cover three papers discussing why reducing the sound horizon is necessary but not sufficient to solve the Hubble tension, how to probe gravitational waves using astrometry, and whether unparticles might have something to do with dark energy. As of this week I’ve also decided to start including plots from the respective papers, where necessary, in my summaries, as a good plot is worth a thousand words. Enjoy!
End of the week wrap-up, which discusses how early dark energy runs into trouble when confronted against large-scale structure full-shape galaxy power spectrum data (with a social injustice metaphor related to bad practices when trying to solve the H0 tension), the puzzling origin of GW190814, and a good ambulance chasing paper which turns XENON1T into a machine to set precise constraints on non-standard neutrino interactions.
This week’s entry features a futuristic way for obtaining a direct geometrical measurement of the Hubble constant using the so-called cosmic secular parallax, a study on the possibility of cross-correlating ultra-high energy cosmic rays and large-scale structure and what we would learn from this cross-correlation, and the second-best constraint on the tidal charge of brane-world black holes from the shadow of M87* detected by the Event Horizon Telescope. Enjoy!
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 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.
With a week of delay, due to my recent travels to Norway, my Week 10 arXiv summaries are out! This week’s papers are all more or less related to dark matter, covering the particle physics, gravitational waves, and cosmology side of the story. Enjoy, and note that Week 11’s summaries are out too!
The common denominator between the 3 papers I selected this week is that they all are, to some extent, provocative, although related to completely different topics (respectively the Hubble tension, possible hints for dark matter in low-threshold direct detection experiments, and the possible need to move beyond archaic units in cosmology). I won’t say anything more to not spoil the fun, so enjoy reading!
