Quasinormal modes-shadow correspondence paper published in PRD!

My paper with Davide Pedrotti, which explores the validity of the eikonal quasinormal modes-shadow radii correspondence for rotating regular black holes (see this earlier news item), has now officially been published in PRD! The full bibliographic coordinates for the paper are Phys. Rev. D 110 (2024) 084075. Here is the link to the paper.

UniTrentoMag piece on fifth forces and Bennu paper

I was interviewed by Alessandra Saletti, head of the University of Trento’s Press Office and External Relations, on our paper on fifth forces and Bennu in Communications Physics. The piece appeared in UniTrentoMag, the University of Trento’s online magazine, and is available both in Italian and English, at the links below:
mag.unitn.it/ricerca/121147/polvere-di-asteroidi-sulle-tracce-della-quinta-forza
mag.unitn.it/ricerca/121147/polvere-di-asteroidi-sulle-tracce-della-quinta-forza#English-version
Enjoy the read!

Alessandro La Sala joins my group!

Today Alessandro La Sala officially joins my group, thus becoming the first BSc student to write his BSc thesis/final project under my supervision. Alessandro is enrolled in the Mathematics BSc, but has a keen interest in physics, and his project will be on the topic of General Relativity and Dark Energy. Welcome Alessandro!

Press release for fifth forces and Bennu paper

APS Reviewer Excellence Award!

I’m absolutely honored to have received the 2024 Reviewer Excellence Award from the American Physical Society, in recognition of my exceptional peer review contributions to PRD. I strongly believe in the value of peer review and always put significant efforts into ensuring my reviews are detailed and helpful for the authors, while upholding the high standards of the journals I review for: I am therefore very glad my efforts have been officially recognized! For me this award is especially valuable coming from PRD, which is both the journal I review the most for, and the journal where I have published the most papers (including my first one).

Varying electron mass and ΛsCDM paper published in PDU!

My paper with Yo Toda, William Giarè, Emre Özülker, and Eleonora Di Valentino, where we attempt to solve the Hubble tension combining a spatially uniform time-varying electron mass in a non-spatially flat Universe, and the ΛsCDM model, featuring a late-time sign-switching cosmological constant (see this earlier news item), has now officially been published in PDU! The full bibliographic coordinates for the paper are Phys. Dark Univ. 46 (2024) 101676. Here is the link to the paper (which is published Open Access).

Quasinormal modes-shadow correspondence paper accepted in PRD!

My paper with Davide Pedrotti, which explores the validity of the eikonal quasinormal modes-shadow radii correspondence for rotating regular black holes (see this earlier news item), has been accepted for publication in PRD! Very minor revisions compared to the previous version include the addition of an extra point for which we tested the correspondence and minor updates to the figures. Unfortunately, during the review process the paper also changed its title (losing its cool first part on the lightning-thunder correspondence!), but we knew far too well that it would have been super hard to keep it. Congratulations Davide for your first paper accepted for publication, and here’s to hoping there will be many more! You can read the preprint version of the paper on arXiv: 2404.07589.

Fifth forces and Bennu paper mentioned in Scientific American

A recent piece in Scientific American, mainly focused on this recent paper on tests of asteroid-mass primordial black holes from Solar System ephemerides, dedicated a paragraph to our recent paper in Communications Physics on using the asteroid Bennu to test dark matter and other aspects of fundamental physics (see this earlier news item), with quotes from first author Yu-Dai Tsai. Here is a link to the piece in Scientific American:
www.scientificamerican.com/article/dark-matter-black-holes-could-fly-through-the-solar-system-once-a-decade/

Varying electron mass and ΛsCDM paper accepted in PDU!

My paper with Yo Toda, William Giarè, Emre Özülker, and Eleonora Di Valentino, where we attempt to solve the Hubble tension combining a spatially uniform time-varying electron mass in a non-spatially flat Universe, and the ΛsCDM model, featuring a late-time sign-switching cosmological constant (see this earlier news item), has been accepted for publication in PDU! Minor revisions compared to the previous version include a small change to the title, small updates to the figures and tables for consistency, and especially a proper Bayesian evidence-based model comparison analysis. You can read the preprint version of the paper on arXiv: 2407.01173.

Teaching feedback

I just received the feedback from students of the courses I delivered last semester (again General Physics I part 2 and Advanced Topics in Theoretical Physics). As with last year, the feedback was excellent, with a satisfaction index of 100% (which in turn gives me lots of satisfaction): particularly appreciated were my efforts to develop the students’ physical intuition, which is something I indeed consistently pay particular attention with. Again, these positive comments will motivate me to do even better next time (when I will also be taking over the Special Relativity course, after decades during which Luciano Vanzo taught it - a rather big pair of shoes to fill)!

Science News interview

I was recently interviewed by Emily Conover for Science News on the puzzling status of cosmological neutrino mass constraints after DESI, with part of the discussion motivated by my recent paper on the topic. It was very nice to chat with an amazing and tremendously well-known journalist such as Emily (whose pieces I highly recommend)! Her extremely nice piece appeared today and, besides from myself, contains quotes from a number of well-known scientists, including Licia Verde, Dan Green, Willem Elbers, as well as my friends and colleagues Miguel Escudero and Eleonora Di Valentino. You can read the full article here:
www.sciencenews.org/article/neutrino-mass-phenomenon-cosmology
I had great fun talking to Emily, and I hope you enjoy the interview!

Fifth forces and Bennu paper published in Communications Physics!

My paper with Yu-Dai Tsai, Davide Farnocchia, Marco Micheli, and Luca Visinelli, where we use OSIRIS-REx tracking data for the asteroid Bennu to set new constraints on fifth forces and ultralight dark matter (see this earlier news item), has now officially been published in Communications Physics (making this my first proper Nature publication)! The full bibliographic coordinates for the paper are Commun. Phys. 7 (2024) 311. Here is the link to the paper (which is published Open Access).

Top 2% scientists (2023 edition)

As with last year, for what it’s worth, it looks like my name appeared in the list of top 2% scientists worldwide, compiled by John Ioannidis at Stanford University, and available here. It seems that for the year 2023 I’ve been ranked 2633rd across all fields, and 28th in my area (looks a bit too high, perhaps it’s because some Scopus research evaluation tool thinks my main area is Nuclear & Particle Physics rather than Astronomy & Astrophysics), whereas considering my whole career the numbers become 67934th and 1228th respectively. Again, all the caveats highlighted last year apply.

Farewell to Jun-Qian Jiang

Today we say farewell to Jun-Qian Jiang, who after an extremely successful 6 months as a long-term visiting PhD student, is returning to China (below is a picture from our farewell pizza dinner at Doc: from left to right we have Simony Santos da Costa, Marco Calzà, Guan-Wen Yuan, Jun-Qian Jiang, and yours sincerely). Jun-Qian’s time here was extremely productive, with 3 very interesting papers, many more in the making, and several key contributions to my group’s activities, for which his arrival was extremely important. Thanks a lot Jun-Qian for everything you taught me, and have a nice trip back to China!

Solar chameleons paper published in PRD!

My paper with Tom O'Shea, Anne Davis, Maurizio Giannotti, Luca Visinelli, and Julia Vogel, where we revisited the issue of production of Solar chameleons (see this earlier news item), has now officially been published in PRD! The full bibliographic coordinates for the paper are Phys. Rev. D 110 (2024) 063027. Here is the link to the paper (which is published Open Access).

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.

Stochastic gravitational wave background from cosmologically coupled black holes

Very happy to see my latest paper with Marco Calzà, Francesco Gianesello, and Max Rinaldi out! This is a 100% “made in Trentino” paper, and more precisely made within the Theoretical Gravitation and Cosmology Group led by myself and Max. At some point in 2023, the possibility that dark energy could be sourced by cosmologically coupled black holes (BHs), whose mass increases in time through purely cosmological growth even in the absence of accretion and merger events, received a lot of interest, especially given the possibility that signatures of such a coupling could have been observed in the growth of supermassive BHs in red-sequence elliptical galaxies. In today’s paper we show that mergers of such cosmologically coupled BHs would lead to a stochastic gravitational wave background whose strength is significantly larger (up to an order of magnitude stronger!) than the standard one from mergers of uncoupled BHs, with very interesting implications for the signal observed last year by pulsar timing arrays (among which NANOGrav, EPTA, PPTA, and CPTA), which is a bit too strong to be easily explainable by mergers of standard BHs. You can read our results in the preprint we just posted on arXiv: 2409.01801.

Solar chameleons paper accepted in PRD!

My paper with Tom O'Shea, Anne Davis, Maurizio Giannotti, Luca Visinelli, and Julia Vogel, where we revisited the issue of production of Solar chameleons (see this earlier news item), has been accepted for publication in PRD! Minor revisions compared to the previous version include a rough estimate of how much the CAST bound on the chameleon-photon coupling changes accounting for the production channels we studied. You can read the preprint version of the paper on arXiv: 2406.01691.

Fifth forces and Bennu paper accepted in Communications Physics!

Very happy to report that my paper with Yu-Dai Tsai, Davide Farnocchia, Marco Micheli, and Luca Visinelli, where we use OSIRIS-REx tracking data for the asteroid Bennu to set new constraints on fifth forces and ultralight dark matter (see this earlier news item), has officially been accepted for publication in the prestigious Communications Physics, part of the Nature Portfolio collection of journals (it is my second time publishing in Nature journals after my 2020 book review in Nature Astronomy, but only the first time publishing a proper original scientific article)! It was quite a long journey, with a couple of rounds of revision on both the scientific and editorial sides, although overall there were no major changes to our results which, if anything, have been clarified better. You can read the preprint version of the paper on arXiv: 2309.13106.