Dr Gregory Ashton

About me

I am a Senior Lecturer in Physics at Royal Holloway, University of London. I began my research career at the University of Southampton, working with Ian Jones and Reinhard Prix, where I completed my PhD in 2016 on Timing variations in neutron stars: models, inference and their implications for gravitational waves. Following this, I held a postdoc position at the Albert Einstein Institute, Hannover, before moving in 2018 to Monash University in Australia to work as an Assistant Lecturer with Paul Lasky. I then briefly joined the Institute for Cosmology and Gravitation (ICG) at the University of Portsmouth, working with Laura Nuttall as a Research Fellow before taking up my current post. My research interest is the relativistic astrophysics of neutron stars and black holes. I am a member of the LIGO Scientific Collaboration and co-chair the Collaboration's largest and most active observational science group, the Compact Binary Group.

• Contact: Send me an email at gregory.ashton@ligo.org
• Publications: See this ADS library or my RHUL Pure portal

News

2025

• 03/11/2025 Today we had a visit from Hampton High School for a collaborative project developing workshops connect to the art exhibition Shadowscapes: Heaney, JMW Turner and Quantum being hosted at the Orleans House Gallery. The twelve students, all enrolled in art GCSE had a varied interest/knowledge of Physics, but Prof. Andrew Casey did a great job of introducing them to some of the key evidence used in the development of Quantum Mechanics, hopefully providing some creative input to their project.

• 17/09/2025 Today concludes SPINS-2025 hosted at RHUL!

• 26/08/2025 It has been a very busy summer, but today the GWTC-4.0 introduction, methods, and results papers landed on arXiv. Below I have added a plot I mocked up for EPO showing the component masses:

• 21/05/2025 RHUL is hosting SPINS-UK 2025
• 19/03/2025 RHUL PhD student Ann Malz is co-hosting the SEPNet student-led conference Exploring the Diversity of Astronomy and Astrophysics Research within GRADnet
• 01/02/2025 Through January and February, we have been observing with RHUL's astrodom

• 17/12/2024 PhD student Ann Malz posted her paper to the arXiv: Classification uncertainty for transient gravitational-wave noise artefacts with optimised conformal prediction

• 13/12/2024 On the final day of a long semester I gave a talk at the ODSL AI4Science Seminar series on Calibrating gravitational-wave search algorithms with conformal prediction

• 23/09/2024 Mattia's paper was published in Phys Rev D

• 23/09/2024 This week is the LVK meeting in Barcelona!

• 11/09/2024 At SPINS-2024 Dr Adriana Dias gave a talk on observing step changes in the periodicities of PSR B1828-11.

• 01/07/2024 Today I was invited to talk at the Gravitational Waves Astrophysics Conference 2024 on "An overview of observational results from the LVK detectors up to the fourth observing run". This was a for-the-LVK talk.

• 18/06/2024 Calibrating gravitational-wave search algorithms with conformal prediction was published in PRD.

• 15/06/2024 Today I lead the Physics department's contributions to the RHUL Science Festival, below is the "Big Bang" explosion from my talk on "Colliding black holes and what they can tell us about quantum gravity".

• 05/06/2024 Today I gave a talk to the Cardiff Gravity Exploration Institute on "Searching and characterizing compact binary coalescence signals: challenges and solutions in real data"

• 29/05/2024 This afternoon I presented at our local seminar on Quantifying Uncertainty with Conformal Prediction.

• 15/05/2024 I visited the Keele Data Science and Astrophysics group and gave a seminar "Gravitational Wave Astronomy: from interferometric strain to astrophysics"

• 25/04/2025 New paper day: Work led by PhD strudent Mattia Emma on Comparing advanced-era interferometric gravitational-wave detector network configurations: sky localization and source properties. We used a lot of CPU hours on this thanks to Oracle for Research for their support. This work also had contributions from Tiago Fernandes de Nobrega, an undergraduate who began the work on low-frequency analyses last year.

2024

• 05/04/2024 This week, I am visiting the IJCLab and gave the invited colloqium

• 18/03/2024 Ronaldas' paper is now published in Phys Rev D!

• 13/03/2024 Mattia ran a IOP-supported student conference Physics is You!

• 29/02/2024 New paper day: Calibrating gravitational-wave search algorithms with conformal prediction is on the arXiv and submitted to Phys Rev D.

2023

• 17/11/2023 New paper day: Work led by Ronaldas Macas Revisiting GW200129 with machine learning noise mitigation: it is (still) precessing

• 07/Aug/2023 We hosted an In2Science student Pavan at RHUL. Pavan built the first iteration of the Duck Detector, a concept idea for a gravitational-wave outreach project (see image below). Overall the project was a success and afterwards Pavan said "He's relentless and passionate about physics and astronomy. He's handled the work experience like an absolute professional rightfully so. My experience couldn't have been any better, thanks to my mentor and his passion towards the subject and his willingness to outreach and teach the ways to young children. The best someone could expect." which I of course was very happy to hear.

• 18/May/2023 I gave a colloqium on Glitch-robust gravitational wave astronomy at Los Alamos (virtually).

• 15/May/2023 I co-organised and helped to run the 6th GWOSC Open Data Workshop. Below is a map of all the study hubs!

• 11/May/2023 I gave a colloqium at the Institute for Cosmology and Gravitation, University of Portsmouth. I talked about Glitch-robust gravitational-wave astronomy!

• 05/Apr/2023 Double new paper day! Jack Heinzel submitted Inferring the Astrophysical Population of Gravitational Wave Sources in the Presence of Noise Transients to MNRAS for review while Rowina Nathan submitted Improving pulsar-timing solutions through dynamic pulse fitting also to MNRAS for review. Both of these are excellent PhD students I have had the good forture to help with their project.

• 06/Feb/2023 My paper Gaussian Processes for Glitch-robust Gravitational-wave Astronomy was published in MNRAS.

2022

• 06/Dec/2022 I was invited to speak on Key results from ground-based gravitational-wave detectors at the GWPAW 2022 meeting.

• 01/Sep/2022 PhD student Mattia Emma started in my group!

• 13/Jul/2022 Our paper Parameterised population models of transient non-Gaussian noise in the LIGO gravitational-wave detectors has been published in CQG.

• 11/Jul/2022 I led the organisation of the Gravitational-wave astronomy parallel session at NAM2022. We where over subscribed by a factor of 2 on talks and the room was full too. Really exciting to see the breadth and talent of people working on GWs in the UK. Thanks to all the other organisers who helped make it happen.

• 04/Jul/2022 My paper with Tim Dietrich The use of hypermodels to understand binary neutron star collisions was published in Nature Astronomy.

• 01/Jun/2022 Our Nested Sampling primer was published in Nature Reviews. While I am first author, you should realise this is because "A" is the first letter of the alphabet! Andrew Fowlie led the effort and I am deeply indepted to him as I learned a lot. My contribution, along with Matt Pitkin and John Veitch was to the gravitational-wave application section.

• 25/May/2022 Today, I joined the smallpeice trust and RHUL's Girl's Into Astrophysics event!

• 29/Apr/2022 It is a new paper day! GWCloud hit the arXiv which details the inner workings of searchable repository for the creation and curation of gravitational-wave inference results. This project started back in 2018 IIRC with several ADACS applications by Paul Lasky. It has been a pleasure to work on and I look forward to the future of the project.

• 27/Apr/2022 Today I had the pleasure of examining a PhD student thesis. I'll delay in giving the name until it is all official. But, they defended very well and can now proudly call themselves Docter!

• 06/Apr/2022 I was a judge for the best Student Prize at BritGrav 2022. The conference consisted of two days of talks from students/postdocs and served as a great display of the exciting science done by scientists in the UK. The quality of talks was fantastic and it was hard to pick between them, but in the end Lucy Thomas won the best talk prize with Marion Cromb and Elsa Teixeira as runners up. Congratulations to them all.

• 01/Feb/2022 I am an Award Lead for the Alan Turing Network Development Award. I'm looking forward to using this to develop some interdisciplinary projects.

2021

• 01/Dec/2021 Today I joined the SEPNet workshop Equality, Diversity & Inclusion – Revisiting the leaky pipeline – short-term contracts and career planning. You can find my slides here.
• 18/Nov/2021 I presented at the Banff IRS workshop Detection and Analysis of Gravitational Waves in the era of Multi-Messenger Astronomy: From Mathematical Modelling to Machine Learning. You can find a recording here and my slides here.

• 17/Nov/2021 With Tim Dietrich, we put out a new preprint Understanding binary neutron star collisions with hypermodels. This one shows some tentative evidence for waveform systematics in a BNS.

• 01/Nov/2021 Today I joined Royal Holloway as a Lecturer in Physics!

• 26/Oct/2021 A paper led by the ICG's Simone Mozzon Does non-stationary noise in LIGO and Virgo affect the estimation of H0? hit the arXiv today.

• 07/Oct/2021 New paper day! Parameterised population models of transient non-Gaussian noise in the LIGO gravitational-wave detectors. This work has taken nearly 2 years from the initial conception, a huge amount of computing, and lots of thinking. I really enjoyed getting into a new aspect of GW astronomy, namely the characterisation of the detector.

• 17/Sep/2021 My daughter Ada was born at 4am. Very happy, excited, and tired!

• 29/Jul/2021 New paper led by PhD student Avi Vajpeyi on A search for intermediate-mass black holes mergers in the second LIGO--Virgo observing run with the Bayes Coherence Ratio

• 14/Jul/2021 Today I helped out in Royal Holloway's Girls into Physics program run by the Small Piece trust where we did Python programming for science

• 29/Jun/2021 The LVK collaboration published Observation of gravitational waves from two neutron star-black hole coalescences in ApJL. This was a really fun project to be involved in. That we can make a definitive statement about the nature of the secondary (light-mass) object with a counterpart is testament to our understanding of controlling systematic uncertainty.

• 17/Jun/2021 We released a new paper: Bilby-MCMC: An MCMC sampler for gravitational-wave inference. This was really fun as I got to write a sampler from scratch and remind myself of all the gory details.

• 16/Jun/2021 I helped out with the Royal Holloway Particle Physics Masterclass introducing python programming.

• 11/May/2021 New paper with PhD student Zhi-Qiang You: Optimized localization for gravitational-waves from merging binaries submitted to MNRAS.

• 10/May/2021 The Gravitational Wave Open Data Workshop #4 kicked off today on gather.town.

• 12/Apr/2021 Today I was elected as co-chair of the LIGO collaboration Compact Binary Coalescence (CBC) group. I join Chad Hanna and Walter Del Pozzo and look forward to helping coordinate the discovery and analysis of signals from colliding black holes and neutron stars.

• 08/Apr/2021 Today I'm taking part in Royal Holloway's Astrophysics Residential for 2021. I'm covering an introduction to programming and how to calculate Pi using random numbers.

• 12/Mar/2021 My students successfully nominated me for a You’re Valued Award at Royal Holloway. I'm proud to add some of their comments here: “Greg is an amazing teacher. His enthusiastic approach to teaching maths to us foundation year students has made us enthusiastic as well. he is very friendly and approachable and when we need help he very patiently helps explain everything to us. He is dedicated to make us understand all the concepts he teaches and help us learn to our best capacity.” and “Greg always focuses on our individual worries and makes sure we understand before moving on. He's very good at teaching and we're happy to have him as our maths professor :)”.

• 08/Feb/2021 I presented Flickering of the Vela pulsar to the CAMK journal club.

• 28/Jan/2021 My PhD student Nikhil Sarin passed his pre-submission milestone. It has been a pleasure to watch Nik develop into a great researcher - his next employer will be lucky to have him.

• 27/Jan/2021 New paper on arXiv! Work led by David Keitel "PyFstat: a Python package for continuous gravitational-wave data analysis" which updates the latest on the PyFstat package for Continuous-Wave analyses.

• 14/Jan/2021 New paper! Work led by Eric Burns "Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin" hits the arXiv.

• 11/Jan/2021 Semester 2 gets underway at RHUL. I'm teaching FY1006 Mathematics II to 140 students in online mode for the foreseable future.

• 07/Jan/2021 I gave a talk titled "The deepening mystery of the Vela radio-pulsar glitch" at the Department of Physics, Bar-Ilan University on our recent Vela paper.

2020

• 04/Dec/2020 I gave an improptu talk to the University of Southampton's astrophysics group on our recent Vela paper.

• 16/Nov/2020 New paper "Flickering of the Vela pulsar during its 2016 glitch" on the arXiv.

• 10/Nov/2020 I was awarded the 2020 USERN Physical and Chemical Sciences prize.

• 04/Nov/2020 I gave a presentation to Royal Holloway's Physics group "Turning Wiggles into Science"