Davide Gerosa

Caltech


by

Frequency-domain waveform approximants capturing Doppler shifts

Katie Chamberlain, Christopher J. Moore, Davide Gerosa, Nicolas Yunes.
arXiv:1809.04799 [gr-qc].

We all know Doppler shifts, right? That’s like the biibouuubiiiiboouuuuuu of an ambulance. That happens to gravitational waves as well. Suppose you have a merging binary which is emitting gravitational waves (bibooou). If that binary is going somewhere (say it’s falling into the gravitational potential of a third body), much like the ambulance, the emitted signal will be Doppler shifted. This paper shows a very nice calculation to incorporate Doppler shifts into gravitational waves.

ps. This started out as Katie’s undergraduate summer project at Caltech. Congrats Katie!


by

Spin orientations of merging black holes formed from the evolution of stellar binaries

Davide Gerosa, Emanuele Berti, Richard O’Shaughnessy, Krzysztof Belczynski, Michael Kesden, Daniel Wysocki, Wojciech Gladysz.
Physical Review D, in press.
arXiv:1808.02491 [astro-ph.HE].

Today’s paper celebrates the wedding of stratrack and precession (the nickname for this project was pretrack 😉 ). We use population synthesis evolution from startrack to predict the parameters of spinning black-hole binaries observed by LIGO. The spin distribution is then propagated from formation to detection using post-Newtonian evolutions from my precession code. The bottom line is that spin measurements can be used to truly reconstruct the binary formation channels, and some specific mechanisms (like mass transfers, tides, natal kicks, supernova’s instabilities etc.). Our database is publicly available (play with it!), as well as a little code to compute gravitational-wave detectabilities.

Supporting material available here.


by

Optimizing LIGO with LISA forewarnings to improve black-hole spectroscopy

Rhondale Tso, Davide Gerosa, Yanbei Chen.
arXiv:1807.00075 [gr-qc].

LISA is going to be amazing: supermassive black-holes, galactic white dwarfs, EMRIs… Besides all of that, LISA can help us doing LIGO’s science better. Some LIGO’s sources (notably, things like GW150914) will show up in LISA years is advance. LISA is going to tell us when (in time) and where (in frequency) LIGO will see these sources. In this paper, we explore the idea of adapting the LIGO noise curve if one knows that a source is coming in (because LISA told us). We apply this idea to ringdown tests of GR, and show how powerful they become!


by

Mining gravitational-wave catalogs to understand binary stellar evolution: a new hierarchical bayesian framework.

Stephen R. Taylor, Davide Gerosa.
arXiv:1806.08365 [astro-ph.HE].
Physical Review D, in press.

Gravitational-wave astronomy is moving. Quickly. In a few years we are going to have large catalogs of many detections, and a whole lot of information to extract from them. Instead of focussing on parameters (masses, spins, redshifts) of single sources, we will want to extract hyperparameters describing physical features of the population (metallicity, natal kicks, common envelope, stellar winds, etc). Here we show how to do this in practice: read our new paper for an amazing journey through hyperlateral cubes, Gaussian process emulators, selection biases, hierarchical modeling and more.

Our tools are publicly available! Here is Steve’s Webpage and our public code.

Update: this is my 25th accepted paper! That’s silver, right?


by

Gravitational-wave astrophysics with effective-spin measurements: asymmetries and selection biases

Ken K. Y. Ng, Salvatore Vitale, Aaron Zimmerman, Katerina Chatziioannou, Davide Gerosa, Carl-Johan Haster.
arXiv:1805.03046 [gr-qc].
Physical Review D, in press.

LIGO can measure spins. Well, effective spins actually. These are special combinations of the two spins (magnitude and direction) and the binary mass ratio. There’s a ton of astrophysics that can be done just with this quantity, but one should always be careful. Today’s paper points out a few important shortcomings when dealing with effective spin measurements. Want to know more about asymmetries and selection biases?

ps. You can hardly find a better than to post a paper on the arxiv than May 4th


by

Black-hole kicks from numerical-relativity surrogate models

Davide Gerosa, François Hébert, Leo C. Stein.
Physical Review D 97 (2018) 104049.
arXiv:1802.04276 [gr-qc].

Surrogate models are fancy interpolation schemes developed to provide accurate (well, really accurate) waveforms directly from numerical relativity simulations. The first surrogate able to model fully precessing systems came up recently (and it’s really an amazing work!). Here we exploit these advances to explore how linear momentum is emitted in generic black-hole mergers, and well as its back-reaction. Black holes get kicked!

Open-source code: homepage, repository.