My group keeps expanding, and now includes Mattia Scotto as well! He will be working on his Master’s thesis under my supervision, where we plan on studying various cosmological signatures of dark energy models featuring a negative cosmological constant (perfect timing given today’s new preprint!), and how the signatures we will find can help us distinguish these models from the cosmological constant of ΛCDM. Welcome Mattia, and I’m looking forward to our work together!
Negative cosmological constant and JWST part 2
Together with Nicola Menci, Shahnawaz Adil, Upala Mukhopadhyay, and Anjan Sen, today we posted a new preprint which is basically the sequel to our earlier negative cosmological constant and JWST paper published in JCAP. What we did here, in no small part thanks to Nicola’s contribution, was to perform a more thorough analysis of JWST data, which significantly strengthens our earlier conclusions and shows that a dark energy model featuring a negative cosmological constant is a very interesting candidate model in light of the JWST observations. One notable addition was our study not only of photometric observations, but also spectroscopic observations from the FRESCO survey, which again confirm the earlier results and at the same time make them much more robust. It was great fun working on this paper, and I learned a lot about high-redshift galaxies! You can read our results in the preprint we just posted on arXiv: 2401.12659.
CosmoVerse seminar
Today I delivered a CosmoVerse seminar by the title of Seven hints that early-time new physics alone is not sufficient to solve the Hubble tension, no surprise focused on my seven hints paper (slides here). The seminar was recorded and posted on YouTube, here is the link. A long and stimulating discussion followed, with several very interesting questions and comments from experts in the field, including Adam Riess, Vivian Poulin, and Leandros Perivolaropoulos. For other videos in this seminar series, check out the CosmoVerse YouTube channel. The next seminar from Stefano Anselmi is one which promises to be very interesting!
Applications for 2 DARKTRACK-funded postdoc positions closed
The applications for 2 DARKTRACK-funded postdoc positions to join my group have now officially closed. I received 62 applications in total, although only 51 are formally complete and can be assessed. Together with other 2 committee members, we will meet in the following days to assess all applications, and we hope to come up with rankings and extend offers, at least informally, by early next week. The number of applications we received is huge for Italian standards, and I want to extend a heartfelt thank you to everyone who applied. I’m sure there are a lot of excellent applications in there!
YouTube videos on our Laniakea paper
A number of well-known YouTubers have provided in-depth coverage of our Laniakea paper over the past two months, with their videos tallying up over a million views! Three stand our particularly:
Anton Petrov - link
Dr. Becky (Rebecca - Becky - Smethurst) - link
PBS Space Time (Matt O’Dowd) - link
I found all three to be excellently presented, and rather accurate scientifically. Funnily enough, I didn’t come across them myself, but they were pointed out to me by three different students (“Prof., your work is on YouTube” 😅). I really enjoyed watching these videos, and I hope you do too!
Laniakea paper accepted in JCAP!
My paper with Leo Giani, Cullan Howlett, Khaled Said, and Tam Davis, where we show how the Hubble tension is worsened when properly accounting for local effects of Laniakea (see this earlier news item), has been accepted in JCAP - excellent Christmas present! There were a few minor changes compared to the previous version, and I especially want to highlight the first sentence from the referee report, which in my opinion really sums up the impact of the paper and of Leo’s exceptional work: “I found this paper to be a significant contribution to the characterization of our local spacetime“ (thank you so much referee, whoever you are!). You can read the preprint version of the paper on arXiv: 2311.00215.
Holidays
I’m now officially off for Christmas holidays (a bit earlier this year to avoid adding an extra two zeros, i.e. two orders of magnitude, to the price for plane tickets)! We’ll be travelling to Spain, where my parents live (the picture below was taken on the beach in Roquetas de Mar). See you again when I’m back in the first half of January!
Abilitazione Scientifica Nazionale as Full Professor in the 02/A2 sector (Theoretical Physics)
After receiving the Abilitazione Scientifica Nazionale (National Scientific Habilitation) as Full Professor in Astrophysics in October, I’ve now officially received it, again as Full Professor, in the competition sector 02/A2 - Theoretical Physics of Fundamental Interactions! This is actually the sector within which I was hired, and therefore this Abilitazione is of more direct relevance to me than the 02/C1 one. The list of candidates who received the Abilitazione in the 02/A2 sector in the same round as me can be found here.
Teaching ends today (for now)
My teaching duties for the autumn semester end today, with the final lecture for the cosmology course focused on deriving the angular power spectrum of CMB temperature anisotropies (a lecture I always particularly enjoy, even though students seem to find it particularly difficult). Unlike the previous semester, this one was much lighter, as I only taught my cosmology course. It was once more very rewarding to interact with a bunch of bright students, whom I really hope enjoyed the course, and whose feedback I look forward to. While the next two months will be devoted to exams (teaching restarts at the end of February), I’ll be able to focus almost entirely on research, with the goal of wrapping up a few papers which are nearly done but just need a final push. So, once more, stay tuned for some interesting work which hopefully will appear in the coming months!
Teaching committee
I’m extremely pleased to have been nominated member of the new Teaching Committee (Commissione Didattica) - “new” given that we just elected the new Head of Department, and this implies a reshuffling/re-election of all committees, councils, and boards. The other members of the committee will be Albino Perego (teaching coordinator and chair of the committee), Stefano Azzini, Roberto Iuppa, Matteo Leonardi, and Marco Zanatta. Our tasks will include taking care of all things teaching-related, and in particular I will be responsible for the theoretical courses at both BSc and MSc levels. It will undoubtedly involve a lot of work, but I am very happy to put myself on the line to help improve our teaching activities, for which we are among the best Italian Universities. I look forward to working with my fellow committee members over the next years!
Tonale Winter School
This week I’m travelling to Passo del Tonale to lecture at the 2023 Tonale Winter School on Cosmology. The weather is fortunately fantastic, with clear skies and a lot of snow (below is the view from my hotel window)! For those of you who might be interested, below are the slides I will use during the lectures, and the questions which will be discussed in the working group sessions:
Lecture 1: Basics of theoretical and observational cosmology [Slides]
Lecture 2: Measuring the Hubble constant – the Hubble tension [Slides]
Lecture 3: How (not) to solve the Hubble tension? [Slides]
Lecture 4: Other tensions and challenges for ΛCDM [Slides]
I have really fond memories from the time I attended as a student in 2014 (fun fact: my roommate was Vivian Poulin, now one of the big names in the Hubble tension game), and I’m looking forward to an exciting week!
Official openings for 2 DARKTRACK-funded postdoc positions
I am officially hiring! Applications are now welcome for 2 DARKTRACK-funded postdoc positions, for which I was previously gathering expressions of interest. Two positions are available, depending on whether or not the candidate holds a PhD at the time of the application:
* call 185/2023: lavoraconnoi.unitn.it/en/research-contracts/department-physics-call-selections-awarding-no-1-research-fellowship-decree-no-185-2023 (for candidates already holding a PhD)
* call 186/2023: lavoraconnoi.unitn.it/en/research-contracts/department-physics-call-selections-awarding-no-1-research-fellowship-decree-no-186-2023 (for candidates yet to obtain their PhD)
Please have a look at the INSPIRE job ad for further details, but make sure you submit all your application material to the above links, as we cannot consider material received via other channels. Please reach out to me if you have further questions about the project or the positions!
Universe Today interview
A few weeks ago I had the pleasure to be interviewed by Fraser Cain, publisher of Universe Today, for his well-known Universe Today Podcast YouTube channel. We mostly talked about my seven hints paper (at a level I would say accessible to those within the general public who are interested in cosmology and keep up at a popular science level with what is going on in the field), as well as a few other things including my current research obsessions (spoiler: it has to do with dark energy). The video interview is now available on YouTube, and you can find it here, or if you prefer you can listen to it on Spotify. In the frame below, I was clearly very amused by something Fraser had just said, whereas he was equally surprised by what I had just said 😄 It was really great fun chatting with Fraser, and I hope you enjoy the interview!
Media coverage for Laniakea paper
Our Laniakea paper has been picked up by Universe Today, who write a nice piece which you can find here:
www.universetoday.com/164198/if-you-account-for-the-laniakea-supercluster-the-hubble-tension-might-be-even-larger/
The same piece was later picked up by Phys.org, and our results were mentioned in passing in the Spanish newspaper El Confidencial (as well as a number of other news outlets). Enjoy the read!
Visit to Ferrara
Yesterday and today I enjoyed visiting the INFN Ferrara division, where I gave a talk on “Searching for dark energy off the beaten track” (slides here). I really enjoyed these two days, especially since I got to catch up with three long-term collaborators but especially friends of mine: Martina Gerbino (who was the postdoc following my day-to-day work during my PhD, and without whose help I certainly wouldn’t be in my position today!), Massimiliano (Massi) Lattanzi, and Thejs Brinckmann. The Ferrara cosmology group led by Paolo Natoli is really fantastic: young, dynamic, talented, diverse, and with a wide range of interests! If Padova is currently the best place for cosmology in Italy, I have no doubts that Ferrara is definitely one of the top places to look out for in the near future (but let’s hope to put Trento on the list soon!), especially in light of Martina’s ERC Starting Grant and the group’s commendable strategy of investing in very young people. Non-scientific highlights included tasting salama, a delicious local specialty, which I highly recommend trying if you get the chance!
Laniakea and the Hubble tension
Extremely excited about my latest work with Leo Giani, Cullan Howlett, Khaled Said, and Tam Davis (all four from the University of Queensland), where we study the impact of Laniakea, the supercluster hosting the Milky Way (also known as our home in the Cosmos) on local cosmological measurements and in particular measurements of the Hubble constant. Our initial hope was that taking into account the local inhomogeneities and anisotropies induced by Laniakea could help alleviate the Hubble tension - surprisingly, we found the opposite! The reason in short is that Laniakea is on average overdense compared to the cosmological background in which it resides, so its effect is the opposite of the prototype one would need to alleviate the Hubble tension locally (e.g. a void) - in other words, if one accounts for Laniakea’s impact on distances when inferring the Hubble constant locally, one should find an even higher Hubble constant, by an amount which we quantify exactly. Congratulations to Leo, who did basically all the heavy-lifting on this paper (incidentally this is what we were working on when he visited), which I expect can become a very important one! You can read our results in the preprint we just posted on arXiv: 2311.00215.
Davide Pedrotti (re)joins my group!
Today Davide Pedrotti, after an excellent MSc defense, (re)joins my group as a PhD student. We will be starting some very cool work on cosmological tensions, while also carrying on Davide’s earlier research interests in black hole physics. Stay tuned in particular for our upcoming paper on the connection between quasinormal modes and shadows for rotating regular BHs, which constituted a major part of Davide’s MSc thesis! Welcome (back) Davide!
Science Magazine interview
I was recently interviewed by Adrian Cho for Science Magazine on the current status of the Hubble tension and what could solve it, with part of the discussion motivated by my seven hints paper. Adrian’s extremely nice piece appeared today and, besides from myself, contains quotes from a number of well-known scientists, including Adam Riess, Tanvi Karwal, Johannes Eskilt, Ryan Keeley, Marc Kamionkowski, and Samuel Goldstein. You can read the full article here:
www.science.org/content/article/universes-puzzlingly-fast-expansion-may-defy-explanation-cosmologists-fret
I had great fun talking to Adrian, and I hope you enjoy the interview!
Expressions of interest for 2 DARKTRACK-funded postdoc positions
As mentioned earlier I am looking to hire 2 postdocs funded by my DARKTRACK project grant, focused on developing new ways to look for dark energy. There are a few bureaucratic steps I need to navigate before I can officially open the application process for these positions, but in the meantime I welcome expressions of interest from qualified and interested candidates. If you are interested, please send me an expression of interest following the indications provided in the INSPIRE job ad, with material to be sent to this AJO eDelivery link by November 23, 2023. As explained in the job ad, the cover letter is particularly important and will play a key role in my evaluation of the expressions of interest, so do pay particular attention to that. Do not hesitate to get in touch if you have further questions about the project or the positions!
Negative cosmological constant and JWST paper published in JCAP!
My paper with Shahnawaz Adil, Upala Mukhopadhyay, and Anjan Sen, studying a dark energy model featuring a negative cosmological constant in light of the JWST observations, 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 2310 (2023) 072. Here is a link to the paper (which is published Open Access).
