Asteroid and fifth forces paper published in JCAP!

My paper with Yu-Dai Tsai, Youjia Wu, and Luca Visinelli on the use of asteroids as a probe of fifth forces, which I previously reported on in an earlier news item, has now officially been published in JCAP! The full bibliographic coordinates for the paper are JCAP 2304 (2023) 031. Here is the link to the paper.

SIGRAV Prize!

I am honored to announce that I have been awarded the 2023 SIGRAV Prize (yes, given the day, I did initially think this was an April’s Fool)! This is one of the most prestigious Italian early-career awards in my field, and is awarded by the Italian Society for General Relativity and Gravitation (SIGRAV) to under-40 promising Italian researchers who have made important contributions to the fields of gravitation, astrophysics, and cosmology. It is a true honor to receive this Prize, which boasts a prestigious list of previous winners, back then young but now all tremendously successful researchers and most of them leaders in their fields, among whom (just to name a few): Augusto Sagnotti, Massimo Bianchi, Massimo Giovannini, Paolo Pani, Alessandra Buonanno, Alberto Vecchio, Rosalba Perna, Mariafelicia De Laurentis, Enrico Barausse, Marica Branchesi, and Davide Gerosa. I will be receiving the Prize (a silver medal) and delivering a plenary talk about my work at the XXV SIGRAV conference in Trieste this September, where the other winners will also be awarded (the other SIGRAV Prize has been awarded to Giulia Gubitosi, whereas the Amaldi medals have been awarded to my colleague and collaborator Joe Silk and Gabriele Veneziano). It is always great to be recognized in one’s home country, and I would like to sincerely thank my mentors and collaborators, without whom this would not have been possible!

Visit by William Giarè

This week we have William Giarè visiting us from the University of Sheffield, funded by a CosmoVerse COST STSM grant, as reported in this earlier news item. We’ll be finalizing a project exploring the state of the dark energy equation of state (pun intended), while starting up a number of other projects somewhat broadly related to cosmological tensions and the nature of dark energy. Looking forward to an exciting week of science!

Caritro Postdoctoral Fellowship

We’re hiring, or rather, trying to hire! The call for the 2023 Caritro Postdoctoral Fellowships is open, and the Theoretical Gravitation and Cosmology group led by Max Rinaldi and myself expects to be able to support at most one application. Caritro Fellowships are founded by the Caritro Foundation, and are meant to offer opportunities for professional growth to young researchers who have not turned 35 years old at the start date of the project, through support for research projects with a maximum duration of 24 months to be started in 2023, whose results are expected to benefit (broadly intended) the Province of Trento. We are looking for a young researcher below the age of 35, already in possession of a PhD, and with an excellent research track in cosmology and gravitation broadly intended, with a broad profile at the interface of theory and data, and experience in tests of fundamental physics from cosmological and astrophysical data. If you are interested, please send us an expression of interest following the indications provided in our INSPIRE job ad (with material preferably sent to this AJO eDelivery link - note that there are several stages of selection, please see towards the end of the INSPIRE job ad for more details): please get in touch if you are interested!

Physics Frontiers Random Questions interview on YouTube

The Random Questions video interview associated to the Physics Frontiers podcast episode on my primordial graviton background paper, which I previously reported on in an earlier news item, has now been published on YouTube. You can find it here, where you can listen to Jim and I discuss a few (truly) random things, from the way I get my ideas, to my career, to culture shock, and so on. I hope you will enjoy it!

Asteroid precession and fifth forces paper accepted in JCAP!

My paper with Yu-Dai Tsai, Youjia Wu, and Luca Visinelli, where we use asteroids as a probe of fifth forces, including those mediated by new ultralight particles which could be the dark matter, has been accepted for publication in JCAP! We find that we can potentially set some of the leading fifth force constraints in a certain range of mediator mass. This is another paper which has gone through a really long journey, as it was conceived during a brainstorm Zoom call in October 2020. We are now developing a number of follow-up ideas with asteroid experts, so stay tuned for more! You can find the preprint version of the paper on arXiv: 2107.04038.

Teaching starts today!

Today marks the start of the new semester, and with it of my teaching duties. I have a particularly heavy teaching load this semester (as a result of my having started mid-semester in October, which implied I obviously could not teach classes in the previous semester), where I’ll be lecturing General Physics I part 2 (basically Classical Thermodynamics, roughly following Zemansky) for the Mathematics BSc, Advanced Topics in Theoretical Physics (which, despite the cryptic name, is an advanced course in Modern Cosmology, which will more or less cover Chapters 1-8 of Dodelson) for the Physics MSc, as well as within the Percorso di Approfondimento in Fisica (PAF), a supplement lecture series for the Physics BSc aimed towards particularly capable and motivated students. Needless to say, I already know that throughout the semester research will proceed on a very low gear in the best of cases (and I hope my collaborators won’t hate me for this! 😝). However, despite the overall heavy load, I really look forward to teaching and interacting with bright young minds! As an aside, all my teaching material (notes, slides, exams, solutions, and so on) will be available, while being regularly updated, on the English and Italian versions of my teaching page.

LQG and Sgr A* paper published in ApJ!

My paper with Misba Afrin and Sushant Ghosh on Loop Quantum Gravity and the shadow of Sgr A*, which I previously reported on in an earlier news item, has now officially been published in ApJ! The full bibliographic coordinates for the paper are Astrophys. J. 944 (2023) 149. Here is the link to the paper (which is published Open Access).

Physics Frontiers podcast episode on the primordial graviton background

In early December 2022 I had the pleasure to be interviewed by Jim Rantschler for his well-known Physics Frontiers podcast, where we talked about my primordial graviton background paper, other stuff in physics, and life in general. The podcast episode is now officially out, and you can find it here, or if you prefer on Spotify. There will also be an associated Random Questions video interview which will appear on the podcast’s YouTube channel in the coming weeks. It was great fun chatting to Jim, and I hope you enjoy the interview!

Early dark energy and massive neutrinos paper published in MNRAS!

My paper with Alex Reeves, Laura Herold, Blake Sherwin, and Elisa Ferreira on early dark energy and massive neutrinos, which I previously reported on in an earlier news item, has now officially been published in MNRAS! The full bibliographic coordinates for the paper are Mon. Not. Roy. Astron. Soc. 520 (2023) 3688. Here is the link to the paper (which is published Open Access).

Visit by Luca Visinelli

And we have more visitors: Luca Visinelli from Shanghai Jiao Tong University will also be here for the next two days! Luca is a close collaborator of mine (he is in fact the person with whom I have the most papers in common, with the reverse also holding), and is a very well-known scientist with broad research interests spanning dark matter, dark energy, and black holes. We’ll take the opportunity to catch up on the many projects we have ongoing, and Luca will also deliver a seminar by the title of “The interplay of primordial black holes and particle dark matter”. To celebrate Luca’s birthday, we enjoyed a nice dinner together with Anjan (see below) at La Grotta, one of my favorite restaurants in Trento. It’s very nice to have people travelling and visiting once more, it was definitely something I had missed during the pandemic!

Universe special issue (successfully) closed

The Universe Special Issue “Dark Matter and Dark Energy: Particle Physics, Cosmology, and Experimental Searches” I guest edited together with Eleonora Di Valentino, Alessandro Melchiorri, Olga Mena, and Luca Visinelli, has officially closed today. I am happy say that it was a great success: we published 21 papers, some of which either already of very high impact, or whose impact I expect will be very high. Some highlights of the Special Issue include the classic Mazur-Mottola 2001 gravastar paper (with nearly 1000 citations!), which had previously remained unpublished for over two decades, with a similar fate for the classic Benaoum 2002 modified Chaplygin gas paper, and finally a nice review on dark radiation by Archidiacono and Gariazzo. It was a great fun to work on this Special Issue, and thanks to all the authors for their very nice contributions!

Visit by Anjan Sen

I’m delighted to host my first official visito here in Trento, Anjan Sen from Jamia Millia Islamia! Anjan is a well-known cosmologist whose recent research interests include the nature of dark energy and cosmological tensions. We have never met in person but have shared many interesting email discussions, and more generally share many common interests among which the cosmological consequences of a negative cosmological constant. Anjan will be visiting us for a week and a half, and will also deliver a seminar by the title of “Story of the Dark Universe”. Looking forward to many interesting discussions!

UniVersum IV

Really excited to be attending UniVersum IV, the fourth edition of the UniVersum series of cosmology meetings, roughly the Italian equivalent of UKCosmo for the UK, or IberiCos for Spain-Portugal. This year’s edition is held, excitingly, in Trento! It also happens to be my first in-person conference after the pandemic. I will be giving a keynote talk on “Cosmic acceleration: now, then, and back then”, whose slides you can find here. Looking forward to lots of interesting discussions!

Associated to TIFPA-INFN

As of today I’m officially associated to INFN, the Italian National Institute for Nuclear Physics. I’m associated through our local TIFPA center, which stands for “Trento Institute for Fundamental Physics and Applications”. In particular, I’ll be a member of the FLAG Iniziativa Specifica, which stands for “Quantum Fields in Gravity, Cosmology and Black Holes”, and focuses on a number of themes which include early-Universe cosmology and black hole physics. Looking forward to many interesting discussions which will come out of this, especially from FLAG!

Early dark energy and massive neutrinos paper accepted in MNRAS!

My paper with Alex Reeves, Laura Herold, Blake Sherwin, and Elisa Ferreira (a very international collaboration, spanning 6 different countries - Switzerland, Germany, Italy, UK, Japan, and Brazil!), where we study whether a cosmological model featuring early dark energy (EDE) and massive neutrinos can alleviate cosmological tensions in a way which bypasses the potential problems EDE faces with galaxy clustering data, has been accepted for publication in MNRAS! We show that the answer is…“yes and no”, in the sense that our paper really reinforces the idea that prior volume effects are very important for EDE, to the extent that some of those which were previously described as problems, just maybe aren’t really problems in the first place. Kudos to Alex and Laura, two outstanding PhD students (though Laura is off to her first postdoc as a Miller fellow at JHU), who did all the heavy-lifting on this paper! It has been quite a journey, considering this paper was born out of Alex’s MSc thesis (Alex did his Part III in Cambridge with me, Blake, and George Efstathiou), whose project was conceived on a stuffy afternoon of July 2020, deep in lockdown period, while the first referee report was humongous to say the least, but really helped improve the paper! You can find the preprint version of the paper on arXiv: 2207.01501.

William Giarè wins STSM grant to visit Trento

We’ll have visitors soon: William Giarè, currently a postdoc at the University of Sheffield, has won a COST short-term scientific mission (STSM) within the CosmoVerse COST Action, which will allow him to visit the University of Trento! COST STSM grants are individual mobility and collaboration grants which are aimed towards fostering collaborations between researchers within a given COST Action. William will be visiting Trento at some point in March, and we plan on finalizing and starting up a number of projects, broadly related to the subject of cosmological tensions, ranging from the nature of dark energy, to the S8 tension “done properly” (I guess you’ll have to wait to see what we mean). We have several interesting things we want to discuss, and I look forward to the visit! Congratulations William!

LQG and Sgr A* paper accepted in ApJ!

The year is off to a truly great start research-wise: my paper with Misba Afrin and Sushant Ghosh, where we test two Loop Quantum Gravity (LQG, which is an interesting candidate framework for quantum gravity)-inspired rotating black hole space-times against the Event Horizon Telescope image of Sgr A*, the black hole at the center of our galaxy, has just been accepted for publication in ApJ! We use the size and shape of the shadow to place limits on a parameter which basically quantifies the strength of LQG effects. Our bounds are of course comparatively weak, but at the same time are interesting as a proof of principle given that there are very few ways (if any at all!) to test LQG from the observational point of view. And kudos to Misba, an outstanding PhD student at Jamia Millia Islamia, who did basically all the heavy-lifting on this paper! You can find the preprint version of the paper on arXiv: 2209.12584.

KICC report out

The Kavli Institute for Cosmology, Cambridge (KICC) 2021 annual report is finally out: www.kicc.cam.ac.uk/files/kicc2021_report_medium.pdf
I feature in various entries, especially a research piece on direct detection of dark energy written together with Anne Davis (Pages 37-38). Enjoy the read (and thanks to KICC for having sent me a physical copy), and I guess this is me officially signing off from Cambridge!