Long and Short Fast Radio Bursts Are Different from Repeating and Nonrepeating Transients

Abstract

We collect 133 fast radio bursts (FRBs), including 110 nonrepeating and 23 repeating ones, and systematically investigate their observational properties. To check the frequency dependence of FRB classifications, we define our samples with a central frequency below/above 1 GHz as subsample I/II. First, we find that there is a clear bimodal distribution of pulse width for subsample I. If we classify FRBs into short FRBs (sFRBs; <100 ms) and long FRBs (lFRBs; >100 ms) as done for short and long gamma-ray bursts (GRBs), the sFRBs at higher central frequency are commonly shorter than those at lower central frequency not only for nonrepeating but also repeating sFRBs. Second, we find that fluence and peak flux density are correlated with a power-law relation of F ∝ S p , obs γ for both sFRBs and lFRBs whose distributions are obviously different. Third, the lFRBs with isotropic energies ranging from 1042 to 1044 erg are more energetic than the sFRBs in the F–DM EX plane, indicating that they are two representative types. Finally, it is interesting to note that the peak flux density behaves independently on the redshift when the distance of the FRBs becomes far enough, which is similar to the scenario of the peak flux evolving with redshift in the field of GRBs. We predict that fainter FRBs at a higher redshift of z > 2 can be successfully detected by FAST and the Square Kilometre Array in the near future.

Temporal Scattering, Depolarization, and Persistent Radio Emission from Magnetized Inhomogeneous Environments Near Repeating Fast Radio Burst Sources

“…The repeaters presented in the first CHIME FRB catalog have relatively larger widths and narrower bandwidth compared with one-off FRBs (Pleunis et al 2021). The behaviors of fluence with respect to peak flux exhibit statistically significant differences between bursts with long and short durations (Li et al 2021c). Multiple origins for the FRB population seem increasingly likely.…”

The Statistical Similarity of Repeating and Non-Repeating Fast Radio Bursts

“…Fast radio bursts (FRBs) are mysterious millisecond-duration radio pulses which occur randomly on the sky (e.g., [1][2][3]). FRBs were first found in archived pulsar survey data more than a decade ago [1], and more than 600 FRBs were reported as of April 2022 (e.g., [4][5][6]). However, the detection rate of FRBs is considered to be ∼10 3 -10 4 sky −1 day −1 [2,[6][7][8][9][10][11][12][13][14][15][16][17], which means that FRBs are not uncommon in the Universe; e.g., 1652 repeating events from FRB 20121102A [18] and 1863 bursts from FRB 20201124A [19] were recently detected by the Five-hundred-meter Aperture Spherical radio Telescope (FAST, Li et al [20]).…”

“…It should be mentioned that there is no unambiguous physical origin for FRBs now. In general, FRBs' millisecond duration and high DM indicate the high brightness temperature (10 32 K -3.5 × 10 35 K) [28] and the corresponding isotropic energy (E) released (10 35 erg-10 44 erg) [5,22,29,30]. Many progenitor models have been proposed to figure out what FRBs are (for a review, see, e.g., [31]), such as mergers of compact objects [32], flaring magnetars [33], young magnetars in supernova remnants [34], collisions between neutron star/magnetar and asteroids [35][36][37][38][39], collisions between episodic magnetic blobs [40], and massive black hole model [41].…”

“…On the other hand, some sources have been repeating (e.g., [53][54][55][56][57]), which led to the successful identification of host galaxies and the precise mensuration of redshifts. Li et al [5] analyzed 133 FRBs, including 110 non-repeating and 23 repeating ones, and proposed to classify FRBs into short and long groups according to pulse duration less than 100 ms or not. Interestingly, they found long FRBs are on average more energetic than short ones about two orders of magnitude.…”

“…However, it is still uncertain whether this classification of FRBs is derived from the intrinsic physical characteristics, and whether repeating or "nonrepeating" is due to observational selection bias-e.g., the monitor is not in the most active window for the "non-repeating" FRBs. Although the astrophysical origins of repeating and non-repeating FRBs are considered to be different (e.g., [61][62][63][64]), another viewpoint that most FRBs may be repeating sources has also been proposed [5,[65][66][67]. It is now accepted that there are usually two types of FRBs, i.e., repeating FRBs and non-repeating FRBs.…”