Davide Gerosa

Caltech


Long-lived inverse chirp signals from core collapse in massive scalar-tensor gravity

Ulrich Sperhake, Christopher J. Moore, Roxana Rosca, Michalis Agathos, Davide Gerosa, Christian D. Ott.
Physical Review Letters 119 (2017) 201103.
arXiv:1708.03651 [gr-qc].

Supernova can be used to test gravity! …and if there’s a massive scalar field around, things get terribly interesting. Here we generalize arXiv:1602.06952 to study stellar collapse in massive scalar-tensor theories of gravity (that is, the graviton is coupled to a massive scalar field) with numerical simulations. The scalar-field mass introduces a dispersion relation, and different GW frequencies travel at different speeds. It might even make sense to target historic supernovae: maybe the tail of the signal is still coming to us!


Impact of Bayesian priors on the characterization of binary black hole coalescences

Salvatore Vitale, Davide Gerosa, Carl-Johan Haster, Katerina Chatziioannou, Aaron Zimmerman.
Physical Review Letters 119 (2017) 251103.
arXiv:1707.04637 [gr-qc].

Bayesian statistics is really cool. It lets you specify clearly and openly all the assumptions that enter an analysis. What’s the effect of these prior assumptions on current inference with gravitational-wave data from black-hole binaries? Here we tackle this question head-on, and perform parameter estimation runs on LIGO data with many (astrophysically motivated!) prior assumptions. Some parameters (like chirp mass) do not suffer from prior choices but others (like the effective spin) do! Specifying the astrophysics as priors is a powerful tool to extract more science from GW data

Posterior sample data release.

Update: at the time of publication, this was the first independent reanalysis of any GW data! (There are many more now…). Also, use our data for your research!


Inferences about supernova physics from gravitational-wave measurements: GW151226 spin misalignment as an indicator of strong black-hole natal kicks

Richard O’Shaughnessy, Davide Gerosa, Daniel Wysocki.
Physical Review Letters 119 (2017) 011101.
arXiv:1704.03879 [astro-ph.HE].

Black-hole data can be used to probe the lives of stars. That’s the promise of gravitational-wave astronomy, right? Here we give it a go. We present a (admittedly) very simple model showing that the misalignment of GW151226 can be easily explained with large natal kicks. I like simple things…

Press release: Rochester Institute of Technology, Caltech’s tweet.
Editor’s coverage in physics.aps.org.
Other press coverage: IOP’s physicsworld.com, Science Daily, Phys.org, astronomy.com, sciencenews, iflscience.


Black-hole kicks as new gravitational-wave observables

Davide Gerosa, Christopher J. Moore.
Physical Review Letters 117 (2016) 011101.
arXiv:1606.04226 [gr-qc].

Black hole kicks are cool: powerful (up to thousands of km/s!) recoils that black holes receive following a merger. Here we show these events might leave an imprint on the emitted gravitational waves, which is potentially detectable by future interferometers.

Selected as PRL Editors’ Suggestion.
Press releases: Cambridge UniversityCambridge Center for Theoretical Cosmology
Other press coverage: Daily Mailphys.org, Particle Bitesegno.gr (Greek), Daily Galaxy, RegisterMedia INAF (Italian), IneffableIsland, AstronomyNow, Accademia delle Stelle (Italian), noticiasdelaciencia (Portuguese).
Blog posts on astrobites and particlebites.
TV interview, aired on Cambridge TV.


Precessional instability in binary black holes with aligned spins

Davide Gerosa, Michael Kesden, Richard O’Shaughnessy, Antoine Klein, Emanuele Berti, Ulrich Sperhake, Daniele Trifirò.
Physical Review Letters 115 (2015) 141102.
arXiv:1506.09116 [gr-qc].

Here we study the stability of black-hole binaries with spins (anti)aligned with the orbital angular momentum. Aligned configurations are points of equilibrium, but are they stable? If the heavier black-hole is aligned and the lighter one is anti-aligned, this turns out to be unstable! And the onset of this instability can be in the LIGO or LISA band!

Selected as PRL Editors’ Suggestion.
Supporting material available here.


Effective potentials and morphological transitions for binary black-hole spin precession

Michael Kesden, Davide Gerosa, Richard O’Shaughnessy, Emanuele Berti, Ulrich Sperhake.
Physical Review Letters 114 (2015) 081103.
arXiv:1411.0674 [gr-qc].

2PN black-hole binary spin precession works exactly like Kepler’s two-body problem. Not kidding: just define effective potentials and divide the phase space into morphologies. The only things you need are a few timescales to play with.

Press releases: Cambridge University, Cambridge Center for Theoretical Cosmology, Ole Miss, UT Dallas.
Other press coverage: Science Daily, phys.org, phys.org (2), Media INAF (Italian), Astroblogs (Dutch), RIA (Russian), Daily News, Science World Report, Tech Times, Tech Times (2)SpaceRef, Space Daily, ECN, R&D, Daily Galaxy, scitechdaily, nanowerk
Supporting material available here.