Gravitational Waves at the University of Portsmouth
Lead Research Organisation:
University of Portsmouth
Department Name: Institute of Cosmology and Gravitation
Abstract
Gravitational waves are one of the most remarkable predictions of Einstein's General Theory of Relativity. These can be thought of as ripples in the fabric of spacetime propagating at the speed of light. Gravitational waves are emitted by non-spherically symmetric accelerated masses, such as two black holes or neutron stars orbiting each other. Gravitational waves are incredibly difficult to detect, but in the last years large-scale observatories, including Advanced LIGO, Advanced Virgo and KAGRA, have reached the necessary sensitivity to observe gravitational waves.
The first gravitational-wave signal observed in September 2015 was produced by two black holes roughly 35 times the mass of our Sun colliding approximately one billion light years away. Since then twelve additional binary black hole mergers have been observed. The crowning achievement of gravitational-wave astronomy to date was the observation of two merging neutron stars in August 2017. This signal was special because it was observed simultaneously as a gamma-ray burst by the Fermi observatory and then, following the release of the gravitational-wave sky localisation region to astronomers, was observed across the electromagnetic spectrum.
The potential of "multi-messenger" astronomy (observing sources with multiple "messengers", such as gravitational-waves, photons, neutrinos or cosmic rays) is remarkable. We can explore the validity of Einstein's theory in one of the most extreme environments possible. We can make an independent measurement of the rate at which the Universe is accelerating. We can probe the nature of matter deep within a neutron star, where it is so dense that 1 teaspoon of material weighs as much as a mountain on the Earth.
However, all of this requires us to actually observe these gravitational-wave signals, reliably estimate their source parameters and to do it quickly enough that we can alert astronomers to search for a coincident signal. In this grant we will develop methods to promptly search data from Advanced LIGO, Advanced Virgo and KAGRA to observe the gravitational-wave signature of merging compact objects. We will ensure that such observations are rapidly localised on the sky and that this information is rapidly communicated to astronomers. We will also develop techniques to further improve the sensitivity of these searches, allowing us to dig deeper into the noise, and to observe new types of compact binary mergers that have not been observed to date.
We will also work to better understand the data that is produced by the LIGO observatories. These gravitational-wave observatories are highly precise and complex machines and producing a "clean" data stream free of instrumental noise is a significant challenge. We will work in collaboration with the instrument scientists at the LIGO sites to "characterise" the data being recorded by these instruments. This will allow us to identify the causes of any "imperfections" in the data stream. These imperfections, which often show up as bangs and whistles in the data, harm our ability to observe genuine astrophysical signals. Additionally, if we do not include the effects of noisy data when assessing the parameters of sources that we observe, we run the risk of quoting incorrect, or biased, parameters for our observations. By identifying the causes of such signals we can fix the instrument to stop them happening. We can also understand the effect that these bangs and whistles will have on our ability to understand our new observations. This problem is illustrated in the online project Gravity Spy. If interested, you can visit the Gravity Spy website and help us in this effort!
The first gravitational-wave signal observed in September 2015 was produced by two black holes roughly 35 times the mass of our Sun colliding approximately one billion light years away. Since then twelve additional binary black hole mergers have been observed. The crowning achievement of gravitational-wave astronomy to date was the observation of two merging neutron stars in August 2017. This signal was special because it was observed simultaneously as a gamma-ray burst by the Fermi observatory and then, following the release of the gravitational-wave sky localisation region to astronomers, was observed across the electromagnetic spectrum.
The potential of "multi-messenger" astronomy (observing sources with multiple "messengers", such as gravitational-waves, photons, neutrinos or cosmic rays) is remarkable. We can explore the validity of Einstein's theory in one of the most extreme environments possible. We can make an independent measurement of the rate at which the Universe is accelerating. We can probe the nature of matter deep within a neutron star, where it is so dense that 1 teaspoon of material weighs as much as a mountain on the Earth.
However, all of this requires us to actually observe these gravitational-wave signals, reliably estimate their source parameters and to do it quickly enough that we can alert astronomers to search for a coincident signal. In this grant we will develop methods to promptly search data from Advanced LIGO, Advanced Virgo and KAGRA to observe the gravitational-wave signature of merging compact objects. We will ensure that such observations are rapidly localised on the sky and that this information is rapidly communicated to astronomers. We will also develop techniques to further improve the sensitivity of these searches, allowing us to dig deeper into the noise, and to observe new types of compact binary mergers that have not been observed to date.
We will also work to better understand the data that is produced by the LIGO observatories. These gravitational-wave observatories are highly precise and complex machines and producing a "clean" data stream free of instrumental noise is a significant challenge. We will work in collaboration with the instrument scientists at the LIGO sites to "characterise" the data being recorded by these instruments. This will allow us to identify the causes of any "imperfections" in the data stream. These imperfections, which often show up as bangs and whistles in the data, harm our ability to observe genuine astrophysical signals. Additionally, if we do not include the effects of noisy data when assessing the parameters of sources that we observe, we run the risk of quoting incorrect, or biased, parameters for our observations. By identifying the causes of such signals we can fix the instrument to stop them happening. We can also understand the effect that these bangs and whistles will have on our ability to understand our new observations. This problem is illustrated in the online project Gravity Spy. If interested, you can visit the Gravity Spy website and help us in this effort!
Publications
Abbott R
(2022)
Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo
in Astronomy & Astrophysics
Abbott R
(2023)
Population of Merging Compact Binaries Inferred Using Gravitational Waves through GWTC-3
in Physical Review X
Abbott R
(2023)
GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo during the Second Part of the Third Observing Run
in Physical Review X
Abbott R
(2022)
Search for Subsolar-Mass Binaries in the First Half of Advanced LIGO's and Advanced Virgo's Third Observing Run.
in Physical review letters
Abbott R
(2021)
GWTC-2: Compact Binary Coalescences Observed by LIGO and Virgo during the First Half of the Third Observing Run
in Physical Review X
Abbott R
(2021)
Search for Lensing Signatures in the Gravitational-Wave Observations from the First Half of LIGO-Virgo's Third Observing Run
in The Astrophysical Journal
Abbott R
(2021)
Observation of Gravitational Waves from Two Neutron Star-Black Hole Coalescences
in The Astrophysical Journal Letters
Abbott R
(2021)
Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3a
in The Astrophysical Journal
Abbott R
(2022)
Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b
in The Astrophysical Journal
Abbott R
(2021)
Population Properties of Compact Objects from the Second LIGO-Virgo Gravitational-Wave Transient Catalog
in The Astrophysical Journal Letters
Description | LIGO Scientific Collaboration |
Organisation | LIGO Scientific Collaboration |
Country | United States |
Sector | Academic/University |
PI Contribution | In this award we have directly contributed to the LIGO Scientific Collaboration. We have discovered numerous compact binary mergers as part of this work, and have contributed to a number of collaboration papers (as listed in the publications section). |
Collaborator Contribution | The LSC is comprised of over 1200 members from around 100 institutions and together we have produced numerous papers in the previous years and made the first observations of compact binary mergers. |
Impact | The LSC has produced significant outputs in the last decade. We identify here outputs to which we have contributed as part of this grant in the relevant sections. |
Title | gwastro/pycbc: 1.18.0 release of PyCBC |
Description | This is the v1.18.0 release of PyCBC. update dependencies (require lalsuite, no longer require emcee) build wheels and update build infrastructure A Docker container for this release is available from the pycbc/pycbc-el7 repository on Docker Hub and can be downloaded using the command: docker pull pycbc/pycbc-el7:v1.18.0 On a machine with CVMFS installed, a pre-built virtual environment is available for Red Hat 7 compatible operating systems by running the command: source /cvmfs/oasis.opensciencegrid.org/ligo/sw/pycbc/x86_64_rhel_7/virtualenv/pycbc-v1.18.0/bin/activate A singularity container is available at /cvmfs/singularity.opensciencegrid.org/pycbc/pycbc-el7:v1.18.0 which can be started with the command: singularity shell --home ${HOME}:/srv --pwd /srv --bind /cvmfs --contain --ipc --pid /cvmfs/singularity.opensciencegrid.org/pycbc/pycbc-el7:v1.18.0 |
Type Of Technology | Software |
Year Produced | 2021 |
Open Source License? | Yes |
Impact | We have begun work to adapt the PyCBC software package (of which Portsmouth researchers are among the primary contributors) to work on LISA. This is work that will continue into the coming years and is expected to make development of analysis techniques and methods for LISA easier in the future. We have also used this software package to analyse LIGO and Virgo gravitational-wave data and discover numerous new compact binary mergers, and characterize them. |
URL | https://zenodo.org/record/4556907 |
Description | Caltech seminar - Gravitational-wave transient noise modelling and mitigation |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Gravitational-wave transient noise poses a challenge in the upcoming LIGO-Virgo-KAGRA fourth observing (O4) run. In this talk, I will briefly introduce gravitational-wave transient noise, followed by a study that estimates how much noise transients affect the electromagnetic follow-up. I will also present how machine learning can be applied in various stages of noise mitigation, ranging from estimating the amount of noise in the data to modelling and removing the noise. I will end the talk by giving my outlook on transient noise mitigation for O4. - Talk given by Ronaldas Macas |
Year(s) Of Engagement Activity | 2023 |
URL | https://www.caltech.edu/campus-life-events/calendar/ligo-seminar-64 |
Description | PhD student lectures |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | Introducing PhD students to GW theory (Einstein field equations, gravitational waves, quadrupole equation) and GW detectors (bar detectors, interferometers, LIGO/Virgo/KAGRA, future detectors. Presented by Ronaldas Macas and Gareth Cabourn Davies. |
Year(s) Of Engagement Activity | 2021,2022 |
Description | Presentation of new paper (on precessing search techniques) at LIGO Virgo collaboration meeting |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | Presented our new research paper to an international collaboration meeting. Almost all experts in this field would have been present, either in person or remotely. |
Year(s) Of Engagement Activity | 2023 |
Description | School visits for public outreach |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | Presenting astronomy and gravitational waves to high school pupils |
Year(s) Of Engagement Activity | 2022,2023 |
Description | Talk at The Gravitational Wave Physics and Astronomy Workshop 2021 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Gareth Cabourn Davies gave a presentation of GWTC-3: Compact Binary Coalescences Observed by LIGO and Virgo During the Second Part of the Third Observing Run at a high-impact international conference. |
Year(s) Of Engagement Activity | 2021 |
URL | https://gwpaw2021.aei.mpg.de/ |
Description | Talk at the National Astronomy Meetinng |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | Opening talk of the gravitational-waves session of the National Astronomy Meeting to introduce later contributed talks. Given by Gareth Cabourn Davies. |
Year(s) Of Engagement Activity | 2022 |
URL | https://nam2022.org/ |