Session J02: Gravitational Waves

Recent Results from LIGO and Virgo

Recently the LIGO and Virgo Collaborations reported on 39 candidate gravitational wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo between 1 April 2019 and 1 October 2019. This new catalog contains events whose sources are black hole binary mergers up to a redshift of $\sim$0.8, as well as events which could plausibly originate from binary neutron stars, neutron star-black hole binaries, or binary black holes. The candidate events which are unambiguously identified as binary black holes (both objects }$\ge 3 \mathrm{M}_\odot$ have total masses between $\sim 14 \mathrm{M}_\odot$ and $\sim 150 \mathrm{M}_\odot$. I will describe these new discoveries and provide an overview of ongoing activities in the LIGO/Virgo search for compact binary coalescences.   

Multiparameter tests of general relativity using multiband gravitational-wave observations

In this talk we will demonstrate that multiband observations of stellar-mass binary black holes by the next generation of ground-based observatories (3G) and the space-based Laser Interferometer Space Antenna (LISA) would facilitate a comprehensive test of general relativity by simultaneously measuring all the post-Newtonian (PN) coefficients. Multiband observations would measure most of the known PN phasing coefficients to an accuracy below a few percent—two orders-of-magnitude better than the best bounds achievable from even ‘golden’ binaries in the 3G or LISA bands. Such multi-parameter bounds would play a pivotal role in constraining the parameter space of modified theories of gravity beyond general relativity   

Gravitational-wave signatures of quantum gravity $\backslash $fs20

h $-abstract-$\backslash $pard We show that gravitational-wave astronomy has the potential to inform us on quantum aspects of black holes. Based on Bekenstein's quantization, we find that black hole area discretization could impart observable imprints to the gravitational-wave signal from a pair of merging black holes, affecting their absorption properties during inspiral and their late-time relaxation after merger. Black hole rotation, ubiquitous in astrophysics, improves our ability to probe these quantum effects. Our analysis shows that gravitational-wave echoes and suppressed tidal heating are signs of new physics from which the fundamental quantum of black hole area can be measured, and which are within reach of future detectors. Our results also highlight the need to derive predictions from specific quantum gravity proposals$\backslash $pard-/abstract-$\backslash $\tex   

Measuring Tidal Deformability and Radii of Neutron Star Sources with Third Generation Gravitational Wave Detector Networks

Third generation gravitational wave detectors such as the Einstein Telescope and Cosmic Explorer could be the newest members of an ever-expanding network of planned ground-based detectors across the globe. In this presentation, we explore how well current detector network configurations constrain the tidal deformability and radii of neutron star sources and how third generation of detectors will improve on these. Specifically, we focus on how the capability of possible 3G detector networks changes for different source equations of state, and source mass.   

Available Data Products from LIGO-Virgo Gravitational Wave Searches

The LIGO Scientific Collaboration (LSC) and Virgo Collaboration have been busily analyzing gravitational-wave (GW) data collected during the third Advanced LIGO/Virgo observing run (O3). We have published several O3 search results to date, including (recently) a catalog of compact binary coalescence events from the first six months of the run and companion papers using that set of events. It is less well-known that, besides the papers themselves, we generally release various data products along with our papers to allow the broader community to access quantitative results and to carry out further science investigations. I will describe these data products and give a quick tour of how to find them online in the GW Open Science Center (GWOSC) and the LIGO Document Control Center (DCC).   

Archival Searches for Stellar-Mass Binary Black Holes in LISA

Stellar-mass binary black holes sweep through the frequency band of the Laser Interferometer Space Antenna (LISA) for months to years before appearing in the audio-band of ground-based gravitational-wave detectors. One can expect several tens of these events up to a distance of 500 Mpc each year. The LISA signal-to-noise ratio for such sources even at these close distances will be too small for a blind search to confidently detect them. However, next generation ground-based gravitational-wave detectors, expected to be operational at the time of LISA, will observe them with signal-to-noise ratios of several thousands and measure their parameters very accurately. By leveraging these capabilities, we can significantly reduce the computational costs of detecting these signals in LISA by using archival searches. We demonstrate that this strategy can reduce the required number of templates for a matched-filter search to a few x 10\textasciicircum 3 allowing us to detect events with signal-to-noise ratios as low as 4 -- 6.We show that such high-fidelity observations of these sources by ground-based detectors helps in archival searches to dig tens of signals out of LISA data each year.   

Gravity Surveys Using a Mobile Atom Interferometer

Measuring gravity is important in geodesy for e.g. hydrological monitoring and mineral exploration. Though atomic gravimeters have become the most sensitive way to measure absolute gravity in well-controlled conditions, the performance of field-operation atomic gravimeters is constrained due to their relatively complex and fragile apparatus. We demonstrate field-operation of a mobile atomic gravimeter for time-variable gravity measurements and gravity surveys. In the laboratory, tidal gravity variation is measured with a sensitivity of 37 n$g$/$\surd $Hz and a long-term stability of better than 2 n$g$, revealing the gravitational ocean loading effect on the local tide in the San Francisco Bay. In gravity surveys on the Berkeley hills, absolute gravity is measured with a sensitivity of \textasciitilde 500 n$g$/$\surd $Hz and precision of \textasciitilde 60 n$g$, obtaining the density of the subsurface rocks from the vertical gravity gradient. This work paves the way for bringing field-operation atomic gravimeters to geodesy.