Big stars burn everything they have, die fast, and produce big black holes. So when you see two black holes together, it’s likely that the big black hole comes from the big star. Or maybe not? Before dying, the big … Continue reading
May 25, 2022
Category Archives: Birmingham
April 8, 2022
The last three years: multiband gravitational-wave observations of stellar-mass binary black hole
Observing gravitational waves from the ground (i.e. LIGO, Virgo, etc) give us a unique view on “the last three minutes” of the life of compact objects before they merge with each other. Going to space (I’m talking to you, LISA!) … Continue reading
March 9, 2022
Deep learning and Bayesian inference of gravitational-wave populations: hierarchical black-hole mergers
It took a while (so many technical challenges…) but we made it! Matt‘s monster paper is finally out! Let me introduce a fully-fledged pipeline to study populations of gravitational-wave events with deep learning. If it sounds cool, well, it is … Continue reading
October 13, 2021
Gravitational-wave population inference at past time infinity
Great Scott, a new paper! When analyzing gravitational-wave data, looking at one black hole at a time is not enough anymore, the fun part is looking at them all together. The issue Matt and I are tackling here is that … Continue reading
October 11, 2021
Nate is joining us!
Nathan Steinle is officially starting his postdoc in the group today! Nate graduated with Mike Kesden at the University of Texas at Dallas and is now working with me and the rest of the Birmingham crowd. Welcome Nate! Hope you … Continue reading
August 6, 2021
Population-informed priors in gravitational-wave astronomy
No black hole is an island entire of itself. We’ve got many gravitational wave events now. One can look at each of them individually (aka “parameter estimation”), all of them together (aka “population”), or each of them individually while they’re … Continue reading
July 14, 2021
Well done Max!
Huge congrats to Maciej (Max) Dabrowny, who just graduated from the University of Birmingham after a very successful research project with us (Max’s project ended up in a paper!). Well done and all the best for the future.
July 11, 2021
Settimana dell’astronomia 2021
I was recently interviewed for the Italian Week of Astronomy (“Settimana dell’Astronomia”), a science festival organized by Fondazione Lombardia per l’Ambiente and supported by various Italian associations, universities, and research centers. Here is the nice clip they put together (I … Continue reading
June 24, 2021
Modeling the outcome of supernova explosions in binary population synthesis using the stellar compactness
Today we go deep into the perilous world of binary population synthesis! Using Nicola’s code MOBSE, our master student Maciej has implemented some new prescriptions for how supernovae explode and produce compact objects. In practice, we use the compactness (that’s … Continue reading
June 10, 2021
A new IREU friend from Missouri
We have a new friend in the group! Meredith Vogel is joining us for her undergraduate summer research project. Meredith is e-visiting us from Missouri State University (but will soon start her grad school at the University of Florida*) and … Continue reading
June 10, 2021
Bayesian parameter estimation of stellar-mass black-hole binaries with LISA
LISA is going to be great and will detect stuff from white dwarfs to those supermassive black-hole that live at the center of galaxies. If we’re lucky (yeah, who knows how many of these we will see), LISA might also … Continue reading
May 27, 2021
Looking for the parents of LIGO’s black holes
Who are the parents of LIGO’s black holes? Stars, most likely. Things like those we see in the sky at night will eventually surrender to gravity and collapse. Some of them will form black holes. Some of them will form … Continue reading
May 11, 2021
Hierarchical mergers of stellar-mass black holes and their gravitational-wave signatures
The quest of finding their astrophysical origin of merging black-hole binaries is now a key open problem in modern astrophysics. Stars are the natural progenitor of black holes: at the end of their lives, the core collapses and leaves behind … Continue reading
April 26, 2021
High mass but low spin: an exclusion region to rule out hierarchical black-hole mergers as a mechanism to populate the pair-instability mass gap
Hierarchical mergers are the new black. LIGO is seeing black holes that are just too big to be there. The reason is that stars, which collapse and produce black holes, do some funny things when they get too massive. Notably, … Continue reading
March 31, 2021
Testing general relativity with gravitational-wave catalogs: the insidious nature of waveform systematics.
General Relativity works well. But we still want to test it, and I guess that’s because it actually works too well (you know, all those quantum things that don’t really fit, etc). And we want to test it with gravitational-wave … Continue reading
March 31, 2021
Group study on BH binaries in AGN disks
This is a quick update some of our group activities… In the past few months we’ve been busy learning about the formation of stellar-mass black-hole binaries in the disks of active galactic nuclei. We organized a journal club and studied … Continue reading
March 9, 2021
A taxonomy of black-hole binary spin precession and nutation
Here is the latest in our (by now long) series of papers on black-hole binaries spin precession. This work was is championed by two outstanding PhD students, Daria (in my group) and Nate (UT Dallas). The key idea behind this … Continue reading
January 29, 2021
Eccentric binary black hole surrogate models for the gravitational waveform and remnant properties: comparable mass, nonspinning case
Orbital eccentricity in gravitational-wave observations has been long neglected. And with good reasons! Gravitation-wave emission tends to circularize sources. By the time black holes are detectable by LIGO/Virgo/LISA/whatever, they should have had ample time to become circular. Unless something exciting … Continue reading
January 22, 2021
HopBham!
We are running a virtual workshop with my group (Bham) and Emanuele Berti’s group at Johns Hopkins University (Hop). It’s an attempt to feel a bit less lonely during the COVID pandemic. Hope this is the opportunity to start new … Continue reading
December 15, 2020
Up-down instability of binary black holes in numerical relativity
[Intro music…Now imagine one of those voices from a TV show trailer…] Up-down instability S01-E03.“Previously on the up-down instability. After finding out that the instability exists (S01-E01) and calculating its analytic endpoint (S01-E02), one terrifying prospect remains. What if it’s … Continue reading
November 25, 2020
A generalized precession parameter chi_p to interpret gravitational-wave data
Spin precession is cool, and we want to measure it. In General Relativity, the orbital plane of a binary is not fixed but moves around. This effect is related to the spin of the orbiting black holes and contains a … Continue reading
November 16, 2020
Nicola joins the band
It’s a great pleasure to welcome Nicola Giacobbo, who starts his postdoc with us today. Nicola completed his PhD and first postdoc year in Padova, and is an expert in population-synthesis simulations, compact binary progenitors, stellar physics, and all those … Continue reading
November 10, 2020
Inferring the properties of a population of compact binaries in presence of selection effects
If you want to know what’s out there, you need to figure out what’s missing. And gravitational-wave astronomy is no exception. We are trying to infer how things like black holes and neutron stars behave in the Universe given a … Continue reading
September 25, 2020
Lincei National Academy prize
I am truly honored to receive this year’s research prize of the Italian Culture Ministry and the Lincei National Academy. The prize is given to Italian researchers in various fields, and this year was awarded in the physical sciences. For more information see here and … Continue reading
September 17, 2020
ERC Starting Grant
I was awarded a Starting Grant from the European Research Council for my program titled “Gravitational-wave data mining”. My team and I will look into gravitational-wave data, machine-learning tools, black-hole binary dynamics, stellar-evolution simulations, etc. The total awarded amount is … Continue reading
September 14, 2020
Daria’s PhD adventure starts here
I am very happy to welcome Daria Gangardt back in my group. We worked together last summer for a short but successful summer project. Now Daria is starting her PhD. I’m honored we can be part together of the next … Continue reading
September 11, 2020
Congrats to MSc students
Congratulations to my Master’s students that graduate this year: Abdullah Aziz and Julian Chan from the University of Birmingham, and Beatrice Basset from the University of Lyon. Well done all, and good luck with your future adventures.
July 30, 2020
Structure of neutron stars in massive scalar-tensor gravity
And here is the latest episode in the series of our massive scalar-tensor gravity papers… After stellar collapse, we now look at how neutron stars look like in this strange theory of gravity (recap: “massive scalar-tensor” means that gravity is … Continue reading
July 15, 2020
Gravitational-wave selection effects using neural-network classifiers
And here is my latest lockdown effort: some experiments in the wonderful and perilous world of machine learning. The idea of this paper is to teach a computer to figure out by itself if a gravitational-wave signal will be detectable … Continue reading
June 12, 2020
Massive black hole binary inspiral and spin evolution in a cosmological framework
Supermassive black hole inspiral and spin evolution are deeply connected. In the early stages when black holes are brought together by star scattering and accretion, spin orientations can change because of interactions with the environment. Later on, when gravitational waves … Continue reading
May 20, 2020
Core collapse in massive scalar-tensor gravity
If General Relativity is too boring, couple it to something else. In this paper we study what happens to stellar collapse and supernova explosions if gravity is transmitted not only with the usual metric of Einstein’s theory (aka the graviton) … Continue reading
May 12, 2020
Astrophysical implications of GW190412 as a remnant of a previous black-hole merger
The latest news from our LIGO/Virgo friends (including some colleagues here in Birmingham) was an astrophysical surprise. The black-hole binary GW190412 is just different from every other one we have had so far. One of the two black holes is about three times larger … Continue reading
May 6, 2020
Mapping the asymptotic inspiral of precessing binary black holes to their merger remnants
A black-hole binary starts its life as two single black holes, and finish it as a single black hole. In between there’s all the complicated dynamics predicted by General Relativity: many orbits, dissipation of energy via gravitational waves, spins that … Continue reading
April 8, 2020
The Bardeen-Petterson effect in accreting supermassive black-hole binaries: a systematic approach
New paper today! We’ve been working on this for a very long time but three weeks of lockdown forced us to finish it. It’s about distorted (aka warped) accretion discs surrounding black holes. If the black hole is spinning and … Continue reading
April 3, 2020
The mass gap, the spin gap, and the origin of merging binary black holes
We’ve been knowing about the mass gap for a while, but I bet “spin gap” sounds new to you, uh? The gap in the spectrum of binary black hole masses is due to pair-instability supernovae (i.e. what happens if a … Continue reading
March 16, 2020
IUPAP General Relativity and Gravitation Young Scientist Prize
I am the recipient of the 2020 IUPAP General Relativity and Gravitation Young Scientist Prize. The prize is awarded by the International Society on General Relativity and Gravitation (ISGRG) through it affiliation with the International Union of Pure and Applied … Continue reading
March 5, 2020
Endpoint of the up-down instability in precessing binary black holes
Sometimes you have to look into things twice. We found the up-down instability back in 2015 and still did not really understand what was going on. Three out of four black hole binaries with spins aligned to the orbital angular … Continue reading
February 26, 2020
Milky Way satellites shining bright in gravitational waves
The LISA data analysis problem is going to be massive: tons of simultaneous sources all together at the same time. In Birmingham we are developing a new scheme to tackle the problem, and here are the first outcomes. We populate … Continue reading
February 26, 2020
Populations of double white dwarfs in Milky Way satellites and their detectability with LISA
The Milky Way, our own Galaxy, is not alone. We’re part of a galaxy cluster, but closer in we have some satellites. The bigger ones are the Large and Small Magellanic Clouds (which unfortunately I’ve never seen because they are … Continue reading
January 28, 2020
Prospects for fundamental physics with LISA
LISA is going to be cool. And not just for your astro-related dreams. Theoretical physicists can have fun too! This community-wide manifesto illustrates just how cool things are going to be with LISA. LISA will constitute a major milestone to … Continue reading
December 13, 2019
Postdoc positions in our group
The Institute for Gravitational Wave Astronomy at the University of Birmingham, UK, invites applications for postdoctoral positions. The Institute provides a vibrant and diverse environment with expertise covering theoretical and experimental gravitational-wave research, with applications to present and future-generation detectors, … Continue reading
December 12, 2019
Leverhulme Trust grant
My Leverhulme Trust grant proposal titled “Black-hole spins and accretion discs with gravitational waves from space” has been selected for funding (PI Davide Gerosa, University of Birmingham). The total awarded amount is GBP 191,417 over 3 years.
December 4, 2019
“Hitting this problem hard enough” on Scientific American
I was recently interviewed for Scientific American about my recent paper on multiple-generation black holes in stellar clusters. Here is the article: “Black Hole Factories May Hide at Cores of Giant Galaxies”. Very happy to be quoted saying “I don’t … Continue reading
November 20, 2019
ESA Voyage 2050
I was selected by the European Space Agency to join the Voyage 2050 Topical Teams. Voyage 2050 is ESA’s long-term programmatic plan to select scientific missions to be launched between 2035 and 2050. I am part of the review panel … Continue reading
November 1, 2019
PhD applications now open!
We’re accepting applications from prospective PhD students. The deadline is Dec 31, 2019 for positions starting in the Fall of 2020. General information on the PhDs in our department PhD projects and prospective supervisors Here below is my project description: Astrophysics and … Continue reading
October 28, 2019
GrEAT PhD winter school
This week I am organizing the GrEAT PhD winter school. GrEAT (which stands for Gravitational-wave Excellence through Alliance Training) is a synergy network between the UK and China. Our program features informal talks in the mornings and hands-on sessions in … Continue reading
October 6, 2019
Winter visitors
Two close collaborators will be visiting my group this winter. Vijay Varma, postdoc at Caltech and expert of numerical relativity surrogate models, will be here on October 7-11. Get ready for his talk “Binary black hole simulations: from supercomputers to … Continue reading
October 3, 2019
Amplification of superkicks in black-hole binaries through orbital eccentricity
Today’s paper is about superkicks. These are extreme configurations of black hole binaries which receive a large recoil. Black hole recoils work much like those of, say, a cannon. As the cannonball flies, the cannon recoils backwards. Here the binary … Continue reading
September 20, 2019
Welcome Matt!
I am very excited to welcome Matthew Mould in my research group. Matt is starting his Ph.D. with me in Birmingham. We already have too many ideas…
September 17, 2019
Machine-learning interpolation of population-synthesis simulations to interpret gravitational-wave observations: a case study
Gravitational-wave astronomy is, seems obvious to say, about doing astronomy with gravitational waves. One has gravitational-wave observations (thanks LIGO and Virgo!) on hand and astrophysical models on the other hand. The more closely these two sides interact, the more we … Continue reading