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Phil Lynch

@physlynch.bsky.social

680 followers 370 following 64 posts

Irish gravitational physicist at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Germany modelling gravitational waves from black hole binaries for the upcoming LISA mission

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Phil Lynch @physlynch.bsky.social · Nov 30

I model the gravitational waves that come from binary black holes where one is a supermassive black hole and the other is a much smaller (but still pretty huge) stellar mass black hole, known as Extreme Mass Ratio Inspirals. As you can see, these things get pretty complicated 🧪⚛️🎢🔭🧮

Phil Lynch @physlynch.bsky.social · 23d

In all the papers I’ve been first author on, I’ve gone with no hyphens. But I have also co-authored papers with “extreme mass-ratio inspiral” and “extreme-mass-ratio inspiral”, so it depends how much you personally like hyphens

Reposted by Phil Lynch

Event Horizon Telescope @ehtelescope.bsky.social · 23d

Groundbreaking new image! The EHT reveals the dynamic environment around black hole M87*.

The 2021 image shows a distinct shift in polarization patterns, tracing changes in magnetic fields near the event horizon.

eventhorizontelescope.org/new-eht-imag...

Reposted by Phil Lynch

Black Hole Perturbation Toolkit @bhptoolkit.bsky.social · 23d

Recent paper the cites the BHPToolkit: "Systematic errors in fast relativistic waveforms for Extreme Mass Ratio Inspirals" by Hassan Khalvati, Philip Lynch, Ollie Burke, Lorenzo Speri, Maarten van de Meent, Zachary Nasipak, arxiv.org/abs/2509.08875

Reposted by Phil Lynch

El Espectro 👻 🎃 @telescoper.bsky.social · 25d

A Decade of Gravitational Waves

This is just a quick post to mark the fact that it is now ten years to the day since the first detection of gravitational waves by Advanced LIGO. The acronym LIGO stands for Laser Interferometer Gravitational-wave Observatory. It wasn't until February 11th 2016 that…

A Decade of Gravitational Waves

This is just a quick post to mark the fact that it is now ten years to the day since the first detection of gravitational waves by Advanced LIGO. The acronym LIGO stands for Laser Interferometer Gravitational-wave Observatory. It wasn't until February 11th 2016 that the result was announced at a press conference (which I blogged about here), but the signal itself arrived on 14th September 2015, exactly a decade ago; the name given to the event was GW150914.

telescoper.blog

Phil Lynch @physlynch.bsky.social · 27d

In short: so long as we're careful, fast EMRI waveforms can be accurate enough for LISA’s science goals including pushing general relativity to its limits

Phil Lynch @physlynch.bsky.social · 27d

The good news is if interpolation errors are controlled so that they’re no bigger than the small mass ratio (say 1 part in 100,000), they won’t hurt parameter estimation.

Phil Lynch @physlynch.bsky.social · 27d

We found that:
1️⃣ For rapidly spinning black holes, you need to include at least ~30 modes to avoid bias.
2️⃣ A smart interpolation method using Chebyshev polynomials can be more efficient, reaching the needed accuracy with far fewer data points, while still being fast enough

Phil Lynch @physlynch.bsky.social · 27d

Our new study looks at hidden systematic errors that can crop up when calculating the flux. We focused on two culprits:
1️⃣ Cutting off the calculation of higher modes
2️⃣ Errors introduced when using interpolating the flux to create fast waveform models

Phil Lynch @physlynch.bsky.social · 27d

We focus on leading order (adiabatic) waveform models where one only needs to balance the flux of energy leaving the system in the form of gravitational waves with the orbital energy lost by smaller black hole

Phil Lynch @physlynch.bsky.social · 27d

But there’s a challenge: to decode these signals, we need waveform models that are both super accurate (tiny phase errors matter!) and super fast (millions of templates are needed to search data).

Phil Lynch @physlynch.bsky.social · 27d

EMRIs can orbit hundreds of thousands of times before merging. Their gravitational waves carry a detailed map of spacetime near supermassive black holes, providing a unique test of Einstein’s theory in the strongest gravity we can observe.

Phil Lynch @physlynch.bsky.social · 27d

Future space missions like LISA will listen to gravitational waves from some of the most extreme events in the universe: Extreme Mass-Ratio Inspirals (EMRIs). These are systems where a stellar mass black hole spirals into a supermassive one while emitting low frequency graviational waves

Phil Lynch @physlynch.bsky.social · 27d

New paper on the arXiv today about systematic errors when modelling the gravitation waveform from extreme mass ratio inspirals and their impact on LISA data science

Huge thanks to my collaborators, especially Hassan Khalvati, for getting this project over the line! 🧪⚛️🔭🧮

arxiv.org/abs/2509.08875

A posting on the arXiv preprint server.

Title: Systematic errors in fast relativistic waveforms for Extreme Mass Ratio Inspirals

Authors: Hassan Khalvati, Philip Lynch, Ollie Burke, Lorenzo Speri, Maarten van de Meent, Zachary Nasipak

Abstract: Accurate modeling of Extreme Mass-Ratio Inspirals (EMRIs) is essential for extracting reliable information from future space-based gravitational wave observatories. Fast waveform generation frameworks adopt an offline/online architecture, where expensive relativistic computations (e.g. self-force and black hole perturbation theory) are performed offline, and waveforms are generated rapidly online via interpolation across a multidimensional parameter space. In this work, we investigate potential sources of error that result in systematic bias in these relativistic waveform models, focusing on radiation-reaction fluxes. Two key sources of systematics are identified: (i) the intrinsic inaccuracy of the flux data, for which we focus on the truncation of the multipolar mode sum, and (ii) interpolation errors from transitioning to the online stage. We quantify the impact of mode-sum truncation and analyze interpolation errors by using various grid structures and interpolation schemes. For circular orbits in Kerr spacetime with spins larger than a≥0.9, we find that ℓmax≥30 is required for the necessary accuracy. We also develop an efficient Chebyshev interpolation scheme, achieving the desired accuracy level with significantly fewer grid points compared to spline-based methods. For circular orbits in Kerr spacetimes, we demonstrate via Bayesian studies that interpolating the flux to a maximum global relative error that is equal to the small mass ratio is sufficient for parameter estimation purposes. For 4-year long quasi-circular EMRI signals with SNRs=O(100) and mass-ratios 10^−4−10^−6, a global relative error of 10−6 yields mismatches <10^−3 and negligible parameter estimation biases.

Reposted by Phil Lynch

Olly Long @hyperbolly.bsky.social · May 21

I’m incredibly proud to be part of this and to have my simulations turn into the first publicly available scattering and dynamical capture waveforms!

Below is a plot I made for the Einstein Toolkit Blue Book (arXiv:2503.12263) showing the waveforms SXS:BBH:3999 (scatter) and SXS:BBH:4000 (capture).

Reposted by Phil Lynch

SXS Collaboration @sxs-collaboration.bsky.social · May 15

When simulating orbiting black holes, we move our grid with the holes! One of the key lessons of general relativity is coordinates are meaningless. We exploit this to choose comoving coordinates where the metric changes as little as possible.

www.youtube.com/watch?v=j4WG...

🧪⚛️🔭

A visualization of the moving mesh in binary black hole merger inspiral simulation

YouTube video by SXS Collaboration

www.youtube.com

Reposted by Phil Lynch

LISA Community @lisacommunity.bsky.social · Apr 10

Welcome to the #LECSTalks! series, where we showcase the people, activity, and science taking place around the LISA Early Career Scientists community. 🎤

Today we feature Ben Leather, postdoctoral researcher at the MPI for Grav Physics, talking about Waveform Modelling with Gravitational Self-Force.

Reposted by Phil Lynch

EGO and the Virgo Collaboration @egovirgo.bsky.social · Mar 20

🍾The LIGO - Virgo - KAGRA Collaboration has announced the detection of the 200th candidate gravitational wave signal in this fourth observation period O4!

Reposted by Phil Lynch

astrafoxen @astrafoxen.bsky.social · Mar 12

I spent almost 2 hours painstakingly copying the orbits of all 128 Saturnian moons from the announcement MPEC and reformatting them for visualization...

Behold, here are the orbits of ALL 128 MOONS OF SATURN. This isn't just a moon system—it's a literal asteroid belt around Saturn! 🧪🔭☄️

Saturn's outer moon system viewed from the north pole of Saturn. Moons orbiting in clockwise (retrograde) orbits have red-colored orbits while moons orbiting counterclockwise (prograde; in the direction of Saturn's spin) are colored blue. With so many irregular moons occupying the same region and intersecting each other, the irregular moon system looks like a donut-shaped vortex surrounding Saturn.

Each of the 128 new moons is highlighted in the diagram with a white point representing their location, and a brighter-colored orbit. Previously-known moons of Saturn are included in the diagram, but are colored darker.

The regular moons of Saturn are colored turquoise and the outermost regular moons (Titan, Hyperion, and Iapetus) labeled with their name.

At the lower left corner are scale indicators to help visualize the scale of Saturn's irregular moon system. A small gray circle at the left left corner is shown to represent the diameter of the Earth-Moon orbital distance. A linear scale bar is labeled "10 million km" (6.2 million mi) to give a standard distance.

View of Saturn's irregular moon system, tilted at an angle to show the toroidal belt-like shape of the system. Each moon is labeled with their names in turquioise. Red orbits = retrograde direction, and blue orbits = prograde direction. Turquoise curves closer to the center are orbits of Saturn's regular moons.

Side view of Saturn's irregular moon system, tilted at an angle to show the toroidal belt-like shape of the system. Red orbits = retrograde direction, and blue orbits = prograde direction. Turquoise curves closer to the center are orbits of Saturn's regular moons.

The irregular moons of Neptune (dark green) are also visible in the background to the right of Saturn. The horizontal red line protruding right of Saturn is the orbit path of Saturn.

Reposted by Phil Lynch

Eryn Cangi, PhD @planetaryemc2.bsky.social · Mar 10

I just don't know what else to say at this point except call your reps (5calls.org) and keep fighting. Do not ignore the chaos. Keeping your head down will not protect you 🔭 #PlanetaryScience #Exoplanets

nasawatch.com/ask-the-admi...

The NASA RIF Has Begun

This was just sent to the NASA workforce:

Reposted by Phil Lynch

KateGraphics @kategraphics.bsky.social · Mar 7

The hardest part of creating a design? Posting it on social media, but anyway, here it is! Neutron stars are insanely dense,(teaspoon of neutron star would weight 4 billion tons on Earth). Some are pulsars, like beacons in space or/and magnetars!

🔭Store: kategraphiccreations.etsy.com
#sciart

Neutron star poster, shown with geometric pulsars going out of it and a magnetic field, geometric, art deco, futuristic #sciart

Reposted by Phil Lynch

KateGraphics @kategraphics.bsky.social · Feb 23

"The team predicts that the two neutron stars will spiral slowly toward each other in a cosmic dance, ultimately colliding in a kilonova explosion." Inspired by @skuthunur.bsky.social article & thanks to @astro-jje.bsky.social for patiently answering all my silly binary star questions! #Sciart

Poster of two binary stars orbiting each other, it has elements that come from the merge of the two stars coming out, like Au,Ag,Th,Rh,Gd,Pu,Pd,Eu art deco style, minimalistic #Sciart

Reposted by Phil Lynch

Black Hole Perturbation Toolkit @bhptoolkit.bsky.social · Feb 21

The 🎉200th paper 🎉 that cites the BHPToolkit: "Lensing and wave optics in the strong field of a black hole" by Juno C. L. Chan, Conor Dyson, Matilde Garcia, Jaime Redondo-Yuste, Luka Vujeva, arxiv.org/abs/2502.14073

Reposted by Phil Lynch

Jake Postiglione @jakepost.tech · Feb 18

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

Evolution of LISA Observables for Binary Black Holes Lensed by an SMBH

Binary 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...

Reposted by Phil Lynch

LIGO Scientific Collaboration @ligo.org · Feb 11

#February11 is the International Day of Women and Girls in Science #IDWGS. Meet some of our international #WomenInSTEM through #HumansOfLIGO

1/🧵

Reposted by Phil Lynch

Black Hole Perturbation Toolkit @bhptoolkit.bsky.social · Feb 10

A new major update to the Teukolsky package has been released (version 1.1.0). A major new feature the the ability to PN expand various Teukolsky radial functions (contribution from Jakob Neef)