Very happy to have posted my first new paper in about 10 months (excluding the CosmoVerse white paper) today (after several months spent applying for grants and teaching, with very little research done), together with Marco Calzà, Davide Pedrotti, and Guan-Wen Yuan, making it yet another paper entirely produced within my group! This is the third chapter in the series on primordial regular black holes as potential dark matter candidates (see the earlier part 1 and part 2, both published in PRD - paper 1 and paper 2), where we consider a completely different metric, which we call the Zhang-Lewandowski-Ma-Yang (ZLMY) BH, after the names of the authors which first proposed it here. This BH has completely different properties with respect to the ones we had considered earlier: it has a very strong theoretical foundation within an effective canonical (loop) quantum gravity framework which addresses the important issue of general covariance, whereas from the phenomenological perspective it is one of the few BHs which is hotter with respect to the Schwarzschild BH. We find that this leads to a smaller asteroid mass window where ZLMY PBHs can account for all the DM, smaller relative to Schwarzschild PBHs of course, a result which completely reverses the trend we found earlier, when the asteroid mass window was significantly enlarged and evaporation constraints could in principle be bypassed. You can read our results in the preprint we just posted on arXiv: 2507.02396.
Visit by Anjan Sen and Antonio Junior Iovino
For the next few days we have the pleasure of hosting Anjan Sen (who already visited us two years ago) and Antonio Junior Iovino, visiting us from Jamia Millia Islamia and NYU Abu Dhabi respectively. They will be giving us two talks respectively on an innovative way of measuring the low-redshift expansion rate and constrain the physics of Dark Energy at characteristic redshifts, and on recent important developments in primordial black hole physics. Welcome Anjan and Antonio!
Marco Calzà is on l'Adige!
Today l’Adige, the main regional newspaper of Trentino-Alto Adige, put out in their printed an extremely nice piece on Marco Calzà and his research (especially on primordial black holes)! Our group, in particular Max, Davide, and myself, is also mentioned in the final paragraph. Very nice to see a well-known newspaper covering the life, career, and work of local researchers, particularly in the case of Marco who has been doing excellent work!
Primordial regular black holes papers published in PRD!
My two papers on primordial regular BHs with Marco Calzà and Davide Pedrotti (see these two earlier news items: part 1 and part 2), where we characterize non-singular primordial BHs as DM candidates, have now officially been published in PRD! The full bibliographic coordinates for the papers are Phys. Rev. D 111 (2025) 024009 and Phys. Rev. D 111 (2025) 042010. Here and here are the links to the papers.
Primordial regular black holes papers accepted in PRD!
Extremely good news today as my two earlier papers on primordial regular BHs with Marco Calzà and Davide Pedrotti (see these two earlier news items: part 1 and part 2), where we characterize non-singular primordial BHs as DM candidates, have both been accepted for publication in PRD! There have been a few changes with respect to the earlier versions (slight changes to the titles, discussions on the time evolution of these BHs added, and a few minor additions), but our main messages are unaltered. You can read the preprint versions of the papers on arXiv: 2409.02804 and 2409.02807.
Primordial regular black holes (part 2)
A truly busy day today, as with Marco Calzà and Davide Pedrotti we posted not one but two papers! In our first paper, covered in this other news item and motivated by the fact that all studies on primordial black holes (PBHs) consider Schwarzschild and Kerr BHs which feature curvature singularities, we took a first step towards studying primordial regular BHs as dark matter (DM) candidates, focusing on phenomenological tr-symmetric metrics. In this paper, we extend our pilot study to non-tr-symmetric metrics, which complicate our work by a fair margin. Aside from the well-known Simpson-Visser metric, the space-times we studied include two metrics inspired by Loop Quantum Gravity, more specifically the Peltola-Kunstatter and D’Ambrosio-Rovelli ones, and in all three cases we find that the “asteroid mass window” where all the DM can be made of PBHs is enlarged. You can read our results in the preprint we just posted on arXiv: 2409.02807.
Primordial regular black holes (part 1)
I would be lying if I didn’t say I am particularly proud of this new paper which appeared today with Marco Calzà and Davide Pedrotti, making it another made in Trentino paper and, especially, another paper entirely produced within my group (note that this paper is for 2/3 made within the Valle dei Laghi, which is where both Marco and Davide originally come from)! There are a huge number of studies on primordial black holes (PBHs) as potential dark matter (DM) candidates, yet virtually (almost) all of these works consider Schwarzschild or Kerr BHs, which suffer from a few well-known problems, including the presence of curvature singularities. In today’s paper we therefore took a first step towards characterizing primordial regular BHs (which, on the contrary, do not feature curvature singularities) as DM candidates, finding that they can potentially lead to a larger “asteroid mass window” where PBHs can make up all the DM. Today’s pilot study is focused on so-called tr-symmetric metrics, which include the well-known Bardeen and Hayward regular BHs, whereas we have also put out a companion paper (covered in this other news item), where we study non-tr-symmetric metrics, which also include metrics inspired from Loop Quantum Gravity. You can read our results in the preprint we just posted on arXiv: 2409.02804.
