1. Introduction
More than 10 years after the discovery of Fast Radio Bursts (FRBs; see Lorimer et al. 2007), an understanding of their origins remains elusive. Only one FRB has been shown to repeat: FRB 121102 (Spitler et al. 2016). Numerous follow-up campaigns have been conducted, or are ongoing (e.g., Scholz et al. 2016; Chatterjee et al. 2017; Gajjar et al. 2017; Marcote et al. 2017; Michilli et al. 2018).
Here, we report non-detection of radio bursts from FRB 121102 during two 5 hr observation sessions on the 100 m Green Bank Telescope in West Virginia, US (GBT) on 2017 December 11, and 2018 January 12. In addition, we report non-detection during an abutting 10 hr observation with the Kunming 40 m telescope in China (KM40), from UTC 10:00 2018 January 12. These observations were part of a simultaneous optical and radio monitoring campaign with the the Caltech HIgh-speed Multi-color CamERA (CHIMERA, Harding et al. 2016).
2. Observations
We observed FRB 121102 for two 5 hr GBT sessions, commencing UTC 2017-12-11T03:00 and 2018-01-12T02:30 using the Breakthrough Listen backend (MacMahon et al. 2017) to record across the nominal bands of the receivers. On 2017 December, 11th, we observed using the 4.0–8.0 GHz receiver (SEFD ∼ 10 Jy). On 2018 January, 12th, we observed using the 1.6–2.6 GHz receiver (SEFD ∼ 10 Jy). During both sessions, we observed 3C161 and PSR B0525 + 21 for flux and polarization calibration. Observations were conducted in 30 minute segments (Table 1).
Table 1. FRB 121102 Observation Details
| Telescope | Scan ID | Frequency band | Flux limita | Date | Duration | |
|---|---|---|---|---|---|---|
| (GHz) | (mJy) | (UTC) | (MJD) | (minutes) | ||
| GBT | 20171211-1 | 4.0–8.0 | 24.8 | 2017-12-11T03:46:40.000 | 58098.1574074074 | 30 |
| GBT | 20171211-2 | 4.0–8.0 | 24.8 | 2017-12-11T03:47:50.000 | 58098.1582175925 | 30 |
| GBT | 20171211-3 | 4.0–8.0 | 24.8 | 2017-12-11T04:18:12.000 | 58098.1793055555 | 30 |
| GBT | 20171211-4 | 4.0–8.0 | 24.8 | 2017-12-11T04:48:22.000 | 58098.2002546296 | 30 |
| GBT | 20171211-5 | 4.0–8.0 | 24.8 | 2017-12-11T05:44:14.000 | 58098.2390509259 | 30 |
| GBT | 20171211-6 | 4.0–8.0 | 24.8 | 2017-12-11T06:14:50.000 | 58098.2603009259 | 30 |
| GBT | 20171211-7 | 4.0–8.0 | 24.8 | 2017-12-11T06:45:01.000 | 58098.2812615740 | 30 |
| GBT | 20171211-8 | 4.0–8.0 | 24.8 | 2017-12-11T07:15:12.000 | 58098.3022222222 | 30 |
| GBT | 20171211-9 | 4.0–8.0 | 24.8 | 2017-12-11T07:45:22.000 | 58098.3231712962 | 14 |
| GBT | 20180112-1 | 1.6–2.6 | 55.6 | 2018-01-12T02:44:37.000 | 58130.1143171296 | 30 |
| GBT | 20180112-2 | 1.6–2.6 | 55.6 | 2018-01-12T03:14:46.000 | 58130.1352546296 | 30 |
| GBT | 20180112-3 | 1.6–2.6 | 55.6 | 2018-01-12T03:44:55.000 | 58130.1561921296 | 30 |
| GBT | 20180112-4 | 1.6–2.6 | 55.6 | 2018-01-12T04:15:04.000 | 58130.1771296296 | 30 |
| GBT | 20180112-5 | 1.6–2.6 | 55.6 | 2018-01-12T04:45:13.000 | 58130.1980671296 | 30 |
| GBT | 20180112-6 | 1.6–2.6 | 55.6 | 2018-01-12T05:15:22.000 | 58130.2190046296 | 30 |
| GBT | 20180112-7 | 1.6–2.6 | 55.6 | 2018-01-12T05:45:31.000 | 58130.2399421296 | 30 |
| GBT | 20180112-8 | 1.6–2.6 | 55.6 | 2018-01-12T06:15:40.000 | 58130.2608796296 | 30 |
| GBT | 20180112-9 | 1.6–2.6 | 55.6 | 2018-01-12T07:03:04.000 | 58130.2937962962 | 28 |
| KM40 | 20180112-10 | 4.7–5.2 | 2536.6 | 2018-01-12T09:59:53.862 | 58130.4165956206 | 600 |
Note.
afor 1 ms pulse width, SNR threshold 7σ.From UTC 2018-01-12T10:00 onwards, the source became visible to the KM40 telescope and was observed for 10 hr over 4.7–5.2 GHz (SEFD ∼ 256 Jy).
3. Results and Discussion
At the GBT, high time resolution (300 μs) Stokes-I spectra (183 kHz frequency resolution) were formed using the Breakthrough Listen spectroscopy suite. These were searched for dispersed pulses consistent with the known 557 pc cm−3 dispersion measure of FRB 121102, using Heimdall (Barsdell et al. 2012). At the KM40, Stokes-I dynamic spectra (64 μs, 1 MHz) were recorded and searched in real-time using the Bear software package (details forthcoming).
No bursts were detected. In contrast, 15 bursts were detected within 30 minutes in previous GBT observations using the same procedure (Gajjar et al. 2017). Taken together, these observations support models that predict episodic emission (Scholz et al. 2016). We publish these non-detections here foremostly so that burst statistics can be determined in combination with other observing campaigns.
Breakthrough Listen is managed by the Breakthrough Initiatives, sponsored by the Breakthrough Prize Foundation.11 Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. VG would like to acknowledge NSF grant 1407804 and the Marilyn and Watson Alberts SETI Chair funds. KJL and YPM were supported by NSFC U15311243, XDB23010200 and Max-Planck partner group with MPIfR. LZY was supported by foundation for Key laboratory of Xinjiang Uygur Autonomous Region (2015KL012).