Davide Gerosa

University of Birmingham


Multiband gravitational-wave event rates and stellar physics

Davide Gerosa, Sizheng Ma, Kaze W.K. Wong, Emanuele Berti, Richard O’Shaughnessy, Yanbei Chen, Krzysztof Belczynski
arXiv:1902.00021 [astro-ph.HE].

The prospect of multiband gravitational-wave astronomy is so so so exciting (I mean, really!). So exciting that we want to make sure once again it’s true; and this is today’s paper. Multiband means seeing the same black hole binary with both LIGO at high frequencies and LISA at low frequencies. LISA observations can serve as precursors for the LIGO mergers, and you can a whole lot of new science (astrophysics, tests of GR, smart data analysis, cosmology, etc). Here we have a new semi-analytic way to estimate the rate (i.e. how many) of multiband events, and we also explore some of the stellar physics one could constraint with them. Enjoy!

Supporting material available here.


COST comes to California!

The COST action GWverse is an impressive network of European researchers and institutions tackling gravitational waves, black holes, etc (i.e. the things I like… sweet!). Together with conferences and outreach, they support collaborative visits between the network members, so here we come. Hey wait a minute, Caltech is kind of far from Europe isn’t it? Here’s the news: Caltech is now an international partner of GWverse, and we’re very happy to host European researchers who want to collaborate with us in sunny southern California.

We’re having our first visitors. Serguei Ossokine from the AEI, is here to work with me on a black-hole binary spin project. Yann Bouffanais from University of Padova (Italy) is coming to collaborate on formation channels.  Welcome Serguei and Yann, and thanks to COST for supporting our science!

europetocaltech.jpg


The binary black hole explorer: on-the-fly visualizations of precessing binary black holes

Vijay Varma, Leo C. Stein, Davide Gerosa.
arXiv:1811.06552 [astro-ph.HE].

As you can imagine, I’m kind of obsessed with black hole binaries. So easy (let’s face it, a black hole is easy! Just mass and spin), but at the same time so terribly complicated… Happy to present our attempt to see the binary dynamics in real time. Technical blah blah: we attach a visualization tool to a numerical relativity surrogate model. Are you ready to be a binary black hole explorer?

Supporting material available here.

precessing

ps. Kids can have fun with black holes too! From mikesmathpage.


Wide precession: binary black-hole spins repeatedly oscillating from full alignment to full anti-alignment

Davide Gerosa, Alicia Lima, Emanuele Berti, Ulrich Sperhake, Michael Kesden, Richard O’Shaughnessy.
arXiv:1811.05979 [gr-qc].

Latest in the series of our spin-precession papers, here we found a thing that was worthy of a new name: wide precession. Another name could have been maximal nutations or something like that. These are black-hole binary configurations where the angle between any of the two spins and the orbital angular momentum changes a lot. Can’t change more actually: spins goes from full alignment to full anti-alignment. And they do it many times.

Supporting material available here.

ps. We found this wide precession during Alicia’s SURF undergraduate summer project at Caltech. Jackpot!


High-accuracy mass, spin, and recoil predictions of generic black-hole merger remnants

Vijay Varma, Davide Gerosa, François Hébert, Leo C. Stein, Hao Zhang.
arXiv:1809.09125 [gr-qc].
Physical Review Letters 122 (2019) 011101.

Black hole mergers are like a scattering problem. Two black holes come in, and one black hole comes out. The difference is a bunch of gravitational waves. Those are nice, of course, but the remnant black hole is important too! Here we provide accurate predictions of the mass, spin and kick of this remnant given the properties of the two merging black holes. If you need those numbers (want to build a waveform family? or test GR perhaps?) just use our python module surfinBH!

Press release: Caltech, Ole Miss.

Bonus note. What if you collide ducks instead of black holes? ducks


Frequency-domain waveform approximants capturing Doppler shifts

Katie Chamberlain, Christopher J. Moore, Davide Gerosa, Nicolas Yunes.
Physical Review D 99 (2019) 024025.
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!