From LSC: “Searching for Gravitational Wave Bursts in Coincidence with Short Duration Radio Bursts”

LSC LIGO Scientific Collaboration

LIGO Scientific Collaboration

VIRGO Collaboration bloc

Several previous LIGO searches have used an approach called “multi-messenger astronomy” to improve our chance of detecting gravitational waves. By looking for gravitational waves and a different kind of signal coming from space at the same time and direction, we can gain a couple of advantages over just looking at one type of data. We can dig deeper into our data because we can ignore all the noise that isn’t consistent with a gravitational wave from a specific time or direction. We can also learn a lot more about what’s happening to the source of the signals when we have two completely different types, just as you can learn more about some terrestrial objects when you can listen to as well as look at them.

Because there is random noise in the detector, we usually find a candidate associated with each radio burst, which may be a gravitational wave or may be noise. In the figure above, the blue dots show the statistics of these candidates. On the average, noise would produce dots lying near the dashed line, but very rarely further left than the solid line – so anything over there would be evidence for gravitational waves. Since we saw nothing standing that far out from the noise, we conclude that there is no evidence of gravitational waves associated with this set of radio bursts. No image credit.

This is the first search in which we’ve looked for gravitational waves associated with radio bursts. If we could detect a gravitational wave and a radio signal from the same source, that could narrow down what type of object the source is. If the gravitational wave is strong enough to see its specific shape through the detector noise, that could narrow down the possible objects even further. LIGO, GEO and Virgo partnered with two radio telescopes. The Robert C. Byrd Green Bank Telescope is located in West Virginia and, with a diameter of over 100 meters, is the world’s largest steerable single dish radio telescope.

NRAO/GBT radio telescope
NRAO/GBT radio telescope, West Virginia

We looked at 27 short radio bursts that were found during searches for previously undiscovered radio pulsars during two of Green Bank’s surveys. We also partnered with the Parkes radio telescope, which is a 64 meter single dish telescope in western Australia, in order to look at Fast Radio Bursts observed in the last few years.

CSIRO/Parkes Observatory
CSIRO/Parkes Observatory, Western Australia

These are mysterious, very short pulses which look like they’re coming from deep space far beyond our own galaxy. While not much is known about them at this point, they could be an entirely new class of astrophysical phenomena. The radio survey data we’re looking at was collected at various times, as far back as 2007 and as recently as 2014.

Theorists have predicted a number of scenarios where short radio pulses and gravitational waves in the LIGO range could be produced simultaneously. A starquake on a neutron star is one example. Another would be the merger of two neutron stars. A short radio signal could occur from “spinning up” one of the merging neutron stars into a pulsar just before the merger. Alternatively, they could merge into a spinning pulsar-like hyper-massive neutron star for a few seconds after the collision. The creation of electromagnetic waves as the gravitational waves themselves move through the matter surrounding the merger is another possible way to make radio waves from a neutron star merger. Farther out in space, some theories predict that huge filaments leftover from the early universe called cosmic strings could create both gravitational wave and radio signals when they fold into a cusp or kink.

The searches in this paper didn’t turn up any evidence for gravitational waves associated with the radio bursts we examined. We will keep searching with Advanced LIGO and other interferometers in the coming science runs. Meanwhile radio astronomers continue to investigate the origin of Fast Radio Bursts. As with other gravitational wave searches, the start of the advanced detector era means these studies are only getting started.

See the full article here .

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About the LSC

The LIGO Scientific Collaboration (LSC) is a group of scientists seeking to make the first direct detection of gravitational waves, use them to explore the fundamental physics of gravity, and develop the emerging field of gravitational wave science as a tool of astronomical discovery. The LSC works toward this goal through research on, and development of techniques for, gravitational wave detection; and the development, commissioning and exploitation of gravitational wave detectors.

The LSC carries out the science of the LIGO Observatories, located in Hanford, Washington and Livingston, Louisiana as well as that of the GEO600 detector in Hannover, Germany. Our collaboration is organized around three general areas of research: analysis of LIGO and GEO data searching for gravitational waves from astrophysical sources, detector operations and characterization, and development of future large scale gravitational wave detectors.

Founded in 1997, the LSC is currently made up of more than 1000 scientists from dozens of institutions and 15 countries worldwide. A list of the participating universities.

Caltech/MIT Advanced aLigo Hanford, WA, USA installation
Caltech/MIT Advanced aLigo Hanford, WA, USA installation

Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA
Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

VIRGO Gravitational Wave interferometer, near Pisa, Italy
VIRGO Gravitational Wave interferometer, near Pisa, Italy