From AAS NOVA: “Searching the Surroundings of a Fast Radio Burst”

AASNOVA

From AAS NOVA

19 March 2021
Tarini Konchady

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Artist’s conception of the localization of a fast radio burst to its host galaxy. Credit: Danielle Futselaar.

Fast radio bursts are mysterious astronomical phenomena — for now. To understand how they form, we need to take a closer look at where they live. A new study does just that, with the help of some very sensitive astronomical instruments.

The Fascination of Fast Radio Bursts

Fast radio bursts (FRBs) are exactly what they say they are: short, bright radio signals that last milliseconds at most. Their energy levels make them especially intriguing, since there aren’t many processes that can produce such large amounts of energy so quickly. Another constraint is that FRBs have been detected in all kinds of galaxies, meaning that whatever produces FRBs can’t be overly unique.

Radio telescopes today have the capability to precisely isolate FRBs in their host galaxies, meaning that we can probe the environments that produce FRB sources. The closest known FRB we’ve confidently isolated is called FRB 20180916B (though see this post for a new discovery that may be closer!), which is nearly 500 million light-years away. High-resolution observations have shown that FRB 20180916B is located in a distinct star-forming region, but what can we see if we look even closer?

In a recent study, a group of researchers led by Shriharsh P. Tendulkar (Tata Institute of Fundamental Research(IN)) studied the surroundings of FRB 20180916B in the highest detail yet, getting down to a scale of hundreds of light-years.

Searching Through Gas and Stars

For their study, Tendulkar and collaborators used the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope and the MEGARA spectrograph on the Gran Telescopio Canarias. Taken together, the observations span mainly optical wavelengths, which are sensitive to gas and stars.

Gran Telescopio Canarias at the Roque de los Muchachos Observatory [Instituto de Astrofísica de Canarias ](ES) on the island of La Palma sited on a volcanic peak 2,267 metres (7,438 ft) above sea level.

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The velocity of gas in the host galaxy of FRB 20180916B, with the location of the FRB shown by a red cross. The contours come from Hubble images of the galaxy and depend on the flux detected in the image. [Adapted from Tendulkar et al. 2021]

The gas serves two important functions: it can be used to determine how much star formation is happening in a region, and it can also be used to measure motion. Tendulkar and collaborators used the latter property to determine that FRB 20180916B’s home region is likely rotating with the large galaxy in its vicinity. This rules out the possibility that the FRB source is actually hosted in a smaller, less distinct satellite galaxy.

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The star-forming region closest to FRB 20180916B as seen by Hubble, with its V-shape highlighted. The FRB’s location is shown by the green ellipse with a green arrow pointing towards it. [Adapted from Tendulkar et al. 2021]

Running Away from Home

Tendulkar and collaborators also found that the star formation happening around FRB 20180916B is at an interesting stage: it’s not extremely active, but it hasn’t gone placid either, suggesting that the region is still rather young.

FRB 20180916B is also a significant distance from the nearest group of stars. So, if the FRB source was born in that group, it had to have traveled between 800,000 to 7 million years to get to where it is now. This puts constraints on what the source of FRB 20180916B is, since not many astronomical objects can remain as energetic as FRB sources as they age.

So what’s behind FRB 20180916B? After considering possible scenarios, Tendulkar and collaborators zero in on X-ray or gamma-ray binaries, which consist of a neutron star and a massive companion star. However, to be certain that these sorts of objects are FRB sources, we’d need large samples of well-studied binaries — which is certainly doable with the radio telescopes we have now!

Citation

“The 60 pc Environment of FRB 20180916B,” Shriharsh P. Tendulkar et al 2021 ApJL 908 L12.
https://iopscience.iop.org/article/10.3847/2041-8213/abdb38

See the full article here .


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The American Astronomical Society(US) is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the advancement of astronomy and closely related branches of science, while the secondary purpose includes enhancing astronomy education and providing a political voice for its members through lobbying and grassroots activities. Its current mission is to enhance and share humanity’s scientific understanding of the universe.

AAS Mission and Vision Statement

The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

Adopted June 7, 2009

The society was founded in 1899 through the efforts of George Ellery Hale. The constitution of the group was written by Hale, George Comstock, Edward Morley, Simon Newcomb and Edward Charles Pickering. These men, plus four others, were the first Executive Council of the society; Newcomb was the first president. The initial membership was 114. The AAS name of the society was not finally decided until 1915, previously it was the “Astronomical and Astrophysical Society of America”. One proposed name that preceded this interim name was “American Astrophysical Society”.

The AAS today has over 7,000 members and six divisions – the Division for Planetary Sciences (1968); the Division on Dynamical Astronomy (1969); the High Energy Astrophysics Division (1969); the Solar Physics Division (1969); the Historical Astronomy Division (1980); and the Laboratory Astrophysics Division (2012). The membership includes physicists, mathematicians, geologists, engineers and others whose research interests lie within the broad spectrum of subjects now comprising contemporary astronomy.

In 2019 three AAS members were selected into the tenth anniversary class of TED Fellows.

The AAS established the AAS Fellows program in 2019 to “confer recognition upon AAS members for achievement and extraordinary service to the field of astronomy and the American Astronomical Society.” The inaugural class was designated by the AAS Board of Trustees and includes an initial group of 232 Legacy Fellows.