Journal
ASTROPHYSICAL JOURNAL LETTERS
Volume 876, Issue 2, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.3847/2041-8213/ab13ae
Keywords
galaxies: dwarf; radiation mechanisms: non-thermal; radio continuum: general
Categories
Funding
- National Science Foundation [AST-1100968]
- EVN project [RP024, RP026]
- NWO Vidi fellowship
- European Research Council (ERC) under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Starting grant [337062]
- ERC Starting Grant BEACON [279702]
- Max Planck Society
- NANO-Grav Physics Frontiers Center - National Science Foundation (NSF) [1430284]
- NSF [AAG 1815242, OIA-1458952, 1407804, 1611606]
- NASA Fermi program
- Marilyn and Watson Alberts SETI Chair funds
- Lorne Trottier Chair in Astrophysics & Cosmology, a Canada Research Chair
- NSERC
- FRQNT/CRAQ
- Spanish Ministerio de Economia y Competitividad (MINECO) under ICCUB (Unidad de Excelencia Maria de Maeztu) [AYA2016-76012-C3-1-P, MDM-2014-0369]
- DRAO Covington Fellowship from the National Research Council Canada
- ERC [617199]
- ERC under the European Union's Horizon 2020 research and innovation programme [694745]
- European Research Council (ERC) [617199] Funding Source: European Research Council (ERC)
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1611606] Funding Source: National Science Foundation
Ask authors/readers for more resources
FRB 121102 is the only known repeating fast radio burst source. Here we analyze a wide-frequency-range (1-8 GHz) sample of high signal-to-noise, coherently dedispersed bursts detected using the Arecibo and Green Bank telescopes. These bursts reveal complex time-frequency structures that include subbursts with finite bandwidths. The frequency-dependent burst structure complicates the determination of a dispersion measure (DM); we argue that it is appropriate to use a DM metric that maximizes frequency-averaged pulse structure, as opposed to peak signal-to-noise, and find DM = 560.57 +/- 0.07 pc cm(-3) at MJD 57,644. After correcting for dispersive delay, we find that the subbursts have characteristic frequencies that typically drift lower at later times in the total burst envelope. In the 1.1-1.7 GHz band, the similar to 0.5-1 ms subbursts have typical bandwidths ranging from 100 to 400 MHz, and a characteristic drift rate of similar to 200 MHz ms(-1) toward lower frequencies. At higher radio frequencies, the subburst bandwidths and drift rate are larger, on average. While these features could be intrinsic to the burst emission mechanism, they could also be imparted by propagation effects in the medium local to the source. Comparison of the burst DMs with previous values in the literature suggests an increase of Delta DM similar to 1-3 pc cm(-3) in 4 yr; though, this could be a stochastic variation as opposed to a secular trend. This implies changes in the local medium or an additional source of frequency-dependent delay. Overall, the results are consistent with previously proposed scenarios in which FRB 121102 is embedded in a dense nebula.
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