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The well-known hardness-duration correlation of gamma-ray bursts (GRBs) is investigated with the data of the 4B catalog. We find that, while the hardness ratio and the duration are obviously correlated for the entire set of the 4B catalog,…
Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the universe. The duration and hardness distribution of GRBs has two clusters, now understood to reflect (at least) two different progenitors. Short-hard GRBs…
We searched for anomalously long GRBs (GRBs) in the archival records of the Burst and Transient Sources Experiment (BATSE). Ten obvious superlong (>500 s) GRBs with almost continuous emission episodes were found. Nine of these events are…
The Burst and Transient Source Experiment (BATSE) classifies cosmological gamma-ray bursts (GRBs) into short (less than 2 s) and long (over 2 s) events, commonly attributed to mergers of compact objects and, respectively, peculiar…
The two widely accepted classes of gamma-ray bursts (GRBs), short and long, are with confidence ascribed to mergers of compact objects and collapse of massive stars, respectively. A third, intermediate/soft class, remains putative. Its…
We present the discovery of two distinct classes in the Swift short duration gamma-ray bursts (S-GRBs) from the X-Ray Telescope (XRT) X-ray afterglow light curve. We find that about 40% of the Swift S-GRBs have an X-ray afterglow light…
Two classes of Gamma-ray bursts (GRBs), corresponding to the short/hard and the long/soft events, with a putative intermediate class, are typically considered in the observer frame. However, when considering GRB characteristics in the…
Gamma-ray bursts (GRBs) are classified as long and short events. Long GRBs (LGRBs) are associated with the end states of very massive stars, while short GRBs (SGRBs) are linked to the merger of compact objects. GRB 200826A was a peculiar…
We analyze BATSE time-tagged event (TTE) data for short gamma-ray bursts (T90 duration < 2.6 s), studying spectral lag vs. peak flux and duration, as well as the number of distinct pulse structures per burst. Performing the…
We study the properties of short gamma-ray bursts (GRBs), based on the assumption that they are all connected to the binary neutron star mergers, whose formation mechanism contains a large amount of uncertainty. In particular, the merger…
We search for faint X-ray bursts with duration 10--300 seconds in the ROSAT PSPC pointed observations with a total exposure of 1.6e7 seconds. We do not detect any events shorter than ~100s, i.e. those that could be related to the classic…
Two types of Gamma-ray bursts (GRBs) are observed: short duration hard spectrum GRBs and long duration soft spectrum GRBs. For many years long GRBs were the focus of intense research while the lack of observational data limited the study of…
The merger of compact binary stars produces short gamma-ray bursts (sGRBs), involving channels such as neutron star - neutron star (BNS) and neutron star - black hole (NS-BH). The association between sGRB 170817A and gravitational wave GW…
We have applied two different automatic classifier algorithms to the BATSE Current GRB Catalog data and we obtain three different classes of GRBs. Our results confirm the existence of a third, intermediate class of GRBs, with mean duration…
The duration of the prompt emission of long gamma-ray bursts is generally considered to be fairly similar to the duration of the activity of the engine in the center of the progenitor star. Here, we investigate the relation between the…
Two classes of GRBs have been confidently identified thus far and are prescribed to different physical scenarios -- NS-NS or NS-BH mergers, and collapse of massive stars, for short and long GRBs, respectively. A third, intermediate in…
Some short GRBs are followed by longer extended emission, lasting anywhere from ~10 to ~100 s. These short GRBs with extended emission (EE) can possess observational characteristics of both short and long GRBs (as represented by GRB…
A possible subclass of gamma-ray bursts -- those with few, wide pulses, spectral lags of order one to several seconds, and soft spectra -- has been identified. Their Log[N]-Log[Fp] distribution approximates a -3/2 power-law, suggesting…
We collect 133 Fast Radio Bursts (FRBs), including 110 non-repeating and 23 repeating ones, and systematically investigate their observational properties. To check the frequency dependence of FRB classifications, we define our samples with…
From Galactic binary sources, to extragalactic magnetized neutron stars, to long-duration GRBs without associated supernovae, the types of sources we now believe capable of producing bursts of gamma-rays continues to grow apace. With this…