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The host galaxy of a fast radio burst

2016; Nature Portfolio; Volume: 530; Issue: 7591 Linguagem: Inglês

10.1038/nature17140

1476-4687

E. F. Keane, S. Johnston, Shivani Bhandari, E D Barr, N. D. R. Bhat, M. Burgay, Manisha Caleb, Chris Flynn, A. Jameson, M. Krämer, Emily Petroff, Andrea Possenti, W. van Straten, M. Bailes, Sarah Burke-Spolaor, Ralph P. Eatough, B. W. Stappers, Tomonori Totani, Mareki Honma, Hisanori Furusawa, Takashi Hattori, Tomoki Morokuma, Yuu Niino, Hajime Sugai, Tsuyoshi Terai, Nozomu Tominaga, Shotaro Yamasaki, Naoki Yasuda, Rebecca Allen, Jeff Cooke, J. Jencson, M. M. Kasliwal, D. L. Kaplan, S. J. Tingay, A. Williams, R. B. Wayth, P. Chandra, D. Perrodin, M. Berezina, M. B. Mickaliger, C. Bassa,

Astrophysical Phenomena and Observations

Observations of a six-day-long radio transient following a fast radio burst have yielded the host galaxy’s redshift, which, combined with the dispersion measure, provides a direct measurement of the cosmic density of ionized baryons in the intergalactic medium including all of the so-called ‘missing baryons’. This paper reports the discovery, with the Parkes radio telescope, of a fast radio burst, FRB 150418. A multi-wavelength multi-telescope follow-up study detected a radio transient two hours after the initial burst, lasting about six days before fading to a quiescent level. The authors interpret this fading source as the afterglow of the FRB. Fast radio bursts are transient radio pulses lasting only a few milliseconds and previously it has not been possible to localize such a burst and determine a redshift. The source of FRB 150418 is identified as an elliptical galaxy with redshift of 0.492. In recent years, millisecond-duration radio signals originating in distant galaxies appear to have been discovered in the so-called fast radio bursts1,2,3,4,5,6,7,8,9. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity, which, in tandem with a redshift measurement, can be used for fundamental physical investigations10,11. Every fast radio burst has a dispersion measurement, but none before now have had a redshift measurement, because of the difficulty in pinpointing their celestial coordinates. Here we report the discovery of a fast radio burst and the identification of a fading radio transient lasting ~6 days after the event, which we use to identify the host galaxy; we measure the galaxy’s redshift to be z = 0.492 ± 0.008. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionized baryons in the intergalactic medium of ΩIGM = 4.9 ± 1.3 per cent, in agreement with the expectation from the Wilkinson Microwave Anisotropy Probe12, and including all of the so-called ‘missing baryons’. The ~6-day radio transient is largely consistent with the radio afterglow of a short γ-ray burst13, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation8 of another recently discovered fast radio burst, suggesting that there are at least two classes of bursts.