# Tag Info

33

All models of gamma-ray bursts involve extremely energetic phenomena: particular types of supernovae, the coalescence of binary compact objects, strong magnetar flares, or tidal disruption events. It turns out that these events are quite rare - so rare, in fact, that GRBs would be expected to occur in a low-redshift Milky Way-like galaxy at a rate of only ...

18

The initial Fermi trigger can be found here, and the following sequence of alerts that were sent out by the LIGO Scientific Collaboration/Virgo Collaboration (LVC) and various electromagnetic observers following-up the event can be found in the GCN circular archive here. This doesn't quite give the whole story of the time line of events, but is a good start ...

16

Faster than light's answer is fine if the gamma ray burst is "pointing" towards us. The emission from rapidly moving material in a GRB is thought to be beamed in the direction of that motion, along the rotation axis of the progenitor object in fact. The opening angle of the beam may only be a few degrees (e.g. Frail et al. 2001), which would mean ...

13

The paper (section 5.1) discusses three possibilities in the context of a relativistic fireball model, where some of the kinetic energy in relativistic jets of material emerging from the explosion is converted into gamma rays. The gravitational wave emission is always "prompt" since any surrounding material is transparent to gravitational waves. In ...

11

Short answer: We're screwed. Long answer: Using the inverse square law, the apparent magnitude of the GRB would be about -36.51, which is about 8091 times brighter than the Sun. That's amazing, but no one would be there to witness it. Earth would be completely roasted, with all life destroyed by the deadly radiation. The ozone layer would also be destroyed, ...

9

I think you may be mixing up "Energy" and "Power" a little here. Power is the rate of Energy output per time. If Power is the speed, then Energy is the distance travelled. Quasars look like stars, from Earth, they give out a light, and while they do vary a little (or a lot) you would not expect to see new ones forming or existing ones fading away. Gamma ...

8

Long and short GRBs are thought to arise from different types of event, involving different types of star. Therefore the question you should be asking is why are their event rates so similar?! Long duration bursts are thought to be produced in the death throes of rapidly, rotating massive stars - the hypernova model. Short GRBs are thought to be produced ...

7

The danger from gamma-ray bursts (GRBs) is the potential to reduce atmospheric ozone drastically, allowing harmful ultraviolet radiation to pass through the atmosphere and make life on Earth much more difficult. However, you have to be fairly close for this to happen. Gehrels et al. (2003) calculated that a typical GRB from a supernova would have to occur ...

6

Based on our understanding of what might be possible causes for GRB, there's nothing to suggest that this phenomena is isolated to other galaxies alone, but we have so far only detected GRB originating from outside of the Milky Way. Good that we did too, because if any of them happened in our cosmic neighborhood and was pointing towards us, it would be the ...

5

You are correct. The AT is short for Astronomical Transient. The follows the year and an arbitary sequence of letters to uniquely identify the event, which is assigned by the Transient Name Server This is the official IAU designation for Supernova Candidates, however true supernovae will be re-designated "SN YYYYX". The neutron star merger was not a ...

4

I'll address WR104 first. The National Geographic article calls it a "potential threat." Yet that potential may be low. There are a slew of articles quoting astronomer Grant Hill on the subject. Hill studied the star and found that it looks like it isn't pointing straight at us. Its axis might be up to 45 degrees in another direction, meaning that ...

4

First of all *not to consider me a conspiracy theorist(, but isn't landing on the moon a questionable issue? Only to conspiracy theorists. To everyone else, no, it's not a questionable issue. My father in law helped send men to the Moon. I have worked with a number of people who sent men to the Moon. I was once called on the carpet in Gene Kranz's office. I ...

3

The interpretation you suggest in the second paragraph is incorrect. It is understandable, since there is a debate in the literature - different papers come to potentially contradicting conclusions. "Excluding a possibility that the event is associated with substantial gamma-ray radiation, directed towards the observer" simply means that no observable GRB ...

3

Not Nuclear fusion; There is also a huge amount of nuclear fusion that creates heavy elements from all the iron there is in neutron star: they in fact are not only made of neutrons. But as said in comment, building of heavier elements rather consumes energy than it generates some. Not sure scientists has a clear agreement on how this works. Gravitational ...

3

When "shape" is used in the context of gamma-ray bursts, it is typically used to refer to the jets emitted on opposite ends of an axis through the source. These jets contain huge amounts of energy, most in the form of photons so high in energy that they are classified as gamma-rays, some of the highest-frequency photons known. The jets are typically emitted ...

3

It turned out to be not real GRB event, just a false alarm. My understanding is that, since the source is actually a steady X-ray source, you have a high count rate level at the base: I am not expert of GRBs, but this high-oscillation behavior seems a characteristics of GRBs: you can see few examples here. In fact, the BAT time resolution is very high ($\... 2 The caption for the graph in the article linked says "Raw Data". And as far as I am acquainted with GRB measurements, the scale of oscillations would fit quite well within error margins. Final Verdict: Could be anything, background noise, instrumental noise/error. It is raw data. Without the characteristics and calibration of instruments, the only relevant ... 2 The energy density of the universe is quite well known. Most seems in the form of what is called "dark energy", which accelerates cosmic expansion. Next comes dark matter, accounting for some 20%, then baryonic matter, about 4%. Electromagnetic radiation (photons) contributes so little that I forgot how much. Most of the energy density in photons is in the ... 2 No energy is in transit as GRBs, just like Gamma rays that started in a GRB. If you remember that all that energy is in the form of radiation, it obeys the same laws as ordinary light: the farther, the dimmer (inverse of square of the distance law). So if you see stars dimmer as they are farther from you, same happens to the RGBs. Radiation from the stars ... 2 Is there a way to know how the magnetic field was at the very beginning of our universe? I don't know of one. But then again I think there was no magnetic field at all at the very beginning of the universe. I can't point to any material that proves this beyond a doubt. But I can say that a quiescent black hole "has no hair", so it has no magnetic field, and ... 2 A gamma ray burst could cause an extinction event. There is no evidence that this has ever happened to the Earth. Gamma ray bursts are rare events, we don't know exactly how rare, but to cause a mass extinction a GRB would need to be near (6000 light years or less is near in this context) and pointed right at Earth. GRBs are rare enough for it to be ... 2 Compact stars are stars of great density; stellar remnants in which the fermion constituents have become degenerate. i.e. white dwarfs and neutron stars (though sometimes black holes would be included). A compact binary is a binary star system containing at least one compact object. 2 I will answer with what I now believe to be the correct answer. We see some gamma-ray burst emission hit our satellite which carries an amount of energy$E_{obs}$. If we say the burst was emitted equally in all directions (isotropic) then we derive a quantity$E_{iso}$. If we say that the burst was actually emitted in a tight beam then we derive$E_\theta\$ ...

1

Although not being an expert on the field, I found a multitude of studies dealing with events which may be used as indicator that a GBR is about to happen somewhere. Research on GBR precusor events range from smaller gamma ray precursors, over gravitiational waves, to thermal signatures, and neutrinos: Sarp Akcay: Forecasting Gamma-Ray Bursts using ...

1

I found a database that contains all GRBs from April 1991-August 1991. However, it has 1637 registered GRBs so it would probably be enough for your purposes. Here is the link-Goddard Space Center GRB Archive. Also, just a fair warning, that website is incredibly old and very difficult to use, it took me nearly fifteen minutes to navigate to the actual ...

1

It's unclear if nuclear energy would be a choice propulsion for a space faring civilization. It's possible, but it's not the only option. That said, if it was the method of choice, it's not at all clear to me that it would be easily detected. Let me preface this with stating that I'm not an expert. There's two kinds of basic nuclear engine that could ...

1

There is a tentative detection of a GRB simultaneously with an FRB, DeLaunay et al 2016. If it is true, it would mean that at least some FRBs have the same origin as some GRBs. Theoretically many possibilities were suggested before and after this tentative, detection. For now they all remain quite speculative, and more observations are required (and ...

1

I doubt two black holes could form within a single star, but they might form from a contact binary. That's a pair of stars so close that they touch and share a single atmosphere. For the stars that made the black holes for the LIGO gravitational wave discovery, just consider two very massive stars that are touching or nearly touching. They would share a ...

1

Yes, on the right track where the energy produced in a supernova can indicate if it was a LGRB or SGRB. An indicative tools stems from the light curves of the remnants, both the afterglow brightness and it's region of explosion can indicatively be traced to how long the event lasted. Large gamma-ray remnants are typically associated with rapid star ...

1

Shortly after their discovery, astronomers realized there were at least two classes of GRB: short events (<2 seconds) and long events (>2 seconds). The long GRB are widely believed to by hypernova, the explosions of massive black holes in very distant galaxies. In fact, they are much further away than even Paczynski and his followers believed at the time ...

Only top voted, non community-wiki answers of a minimum length are eligible