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Jake Postiglione
@jakepost.tech

Ever wonder how gravitational wave detectors like LISA would hear the signal of binary black holes orbiting around a supermassive black hole? 🔭 Well check out my first 1st author paper investigating that very topic, live on the arXiv today! 🔥📄 arxiv.org/abs/2502.10591 Explainer in 🧵👇 1/10

arxiv.orgEvolution of LISA Observables for Binary Black Holes Lensed by an SMBHBinary black holes (BBH) are expected to form and merge in active galactic nuclei (AGN), deep in the potential well of a supermassive black hole (SMBH), from populations that exist in a nuclear star c...

19 reposts63 likes

Jake Postiglione
@jakepost.tech

LISA is a space-based gravitational wave detector set to launch in the mid-2030s 📅. It is designed to capture low-frequency gravitational waves. Unlike LIGO, which detects the final merger of a compact binary, LISA would capture the evolution of the system as the objects grow closer together. ⏳ 2/10

Jake Postiglione
@jakepost.tech

In this paper, we considered a binary similar to GW150914 – binary black holes of ~36 and ~29 solar masses. If LISA had been observing, it would’ve detected this system years before ground detectors did! BUT, we placed the binary in orbit around a supermassive black hole of 10^8 solar masses. 👀 3/10

Jake Postiglione
@jakepost.tech

Stellar mass black holes in active galactic nuclei end up in circularized orbits very close to the central supermassive black hole. If two form a binary while orbiting that close, the gravitational waves emitted experience intense gravitational lensing! 🔎 4/10

Jake Postiglione
@jakepost.tech

The main effects that we consider on the lensing of the gravitational wave signal are: 🔹Frequency shifts from orbital motion 🔹Redshifting due to the gravitational well 🔹Magnification near the SMBH Each shaping what LISA will detect! 🌠 5/10

ratpoison.bsky.social
@ratpoison.bsky.social

Neat. Is the presumption of BBH circularity just for tractability? (That's what I take from the end of §2.3 and ignoring tidal effects). Are you also assuming all the spin axes are parallel? Do your guts tell you anything about immersing the BBH in a more realistic SMBH disk?