Related papers: Ultrahigh Energy Activity in Giant Magnetar Outbur…
In the last few years it has been recognized that two apparently distinct classes of peculiar high-energy sources are actually related and can be explained as young neutron stars with magnetic fields as high as 10e14 - 10e15 Gauss. One of…
Magnetars comprise two classes of rotating neutron stars (Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars), whose X-ray emission is powered by an ultrastrong magnetic field, B ~ 10^15 G. Occasionally SGRs enter into active episodes…
We estimate the high energy neutrino flux from the giant flare of SGR 1806-20 on December 27, 2004, which irradiated Earth with a gamma-ray flux ~10^4 times larger than the most luminous gamma-ray bursts (GRBs) ever detected. The Antarctic…
On 2004 December 27, a giant flare from the soft gamma repeater 1806$-$20 was observed. The radiation mechanism of the initial peak of the flare would be controversial. In this letter we point out that very high-energy cosmic rays would be…
Recently an extraordinarily bright gamma-ray burst, GRB 221009A, was observed by several facilities covering the whole electromagnetic spectrum. Gamma rays with energies up to 18 TeV were detected, as well as a possible photon with 251 TeV.…
Gamma-ray bursts (GRBs) have been proposed as one of promising sources of ultra-high-energy cosmic rays (UHECRs), but observational evidence is still lacking. The nearby B.O.A.T. (brightest of all time) GRB 221009A, an once-in-1000-year…
Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with…
The giant flare of 1998 August 27 from SGR 1900+14 was extraordinary in many ways: it was the most intense flux of gamma rays ever detected from a source outside our solar system; it was longer than any previously detected burst from a soft…
Soft gamma repeaters (SGRs) are "magnetars", a small class of slowly spinning neutron stars with extreme surface magnetic fields, ~10^15 gauss. On 2004 December 27, a giant flare was detected from the magnetar SGR 1806-20, the third such…
The extraordinary giant flare of 1998 August 27 from SGR 1900+14 was the most intense event ever detected from this or any other cosmic source (even more intense than the famous March 5th 1979 event). It was longer than any previous burst…
A small air shower array operating over many years has been used to search for ultra-high energy (UHE) gamma radiation ($\geq 50$ TeV) associated with gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton Gamma-Ray…
Young neutron stars born with magnetic fields $B\gtrsim 10^{16}$ G become hyperactive as the field inside the star evolves through ambipolar diffusion on a timescale $\sim 10^9$ s. We simulate this process numerically and find that it can…
We first review on the peculiar characteristics of the bursting and flaring activity of the Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars. We then report on the properties of the SGR 1806-20's Giant Flare occurred on 2004 December…
The multi-wavelength observations of the 2004 December~27 Giant Flare (GF) from SGR 1806-20 and its long-lived radio afterglow are briefly reviewed. The GF appears to have been produced by a dramatic reconfiguration of the magnetic field…
Soft gamma repeaters are high-energy transient sources associated with neutron stars in young supernova remnants. They emit sporadic, short (~ 0.1 s) bursts with soft energy spectra during periods of intense activity. The event of March 5,…
Neutron stars with very strong magnetic fields are known as magnetars. There are multiple theories that predict magnetars may be able to emit high-energy (HE) neutrinos through hadronic processes by accelerating cosmic rays to high…
In 2004, SGR 1806-20 underwent a period of intense and long-lasting burst activity that included the giant flare of 27 December 2004 -- the most intense extra-solar transient event ever detected at Earth. During this active episode, we…
The diffuse relic neutrinos with light mass are transparent to Ultrahigh energy (UHE) neutrinos at thousands EeV, born by photoproduction of pions by UHE protons on relic 2.73 K BBR radiation and originated in AGNs at cosmic distances.…
The soft gamma-ray repeater SGR 1806-20 has been attracting a lot of attention owing to the fact that in December 2004 it emitted the most powerful giant flare ever observed. Here we present the results of the first Suzaku observation of…
In December 2004, the soft gamma-ray repeater SGR 1806-20 emitted the most powerful giant flare ever observed. This probably involved a large-scale rearrangement of the magnetosphere leading to observable variations in the properties of its…