
Astronomers Detect Record-Breaking Gamma Ray Bursts - whocansay
https://www.smithsonianmag.com/science-nature/astronomers-detect-record-breaking-gamma-ray-bursts-colossal-explosion-space-180973610/
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gigatexal
“ Gamma rays are the highest-energy form of radiation, with wavelengths that
can be smaller than the nucleus of an atom. (Radio waves, for comparison, have
wavelengths ranging between about a millimeter to hundreds of kilometers.)”

This is so insane to me. I knew the wavelengths were small but not this small.
Nature is so cool!

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maxnoe
Doesn't really make sense to speak of wavelengths at these energies any more.
For all intents and purposes, these are particles.

The energies we detect go into the hundreds of TeVs and charged cosmic rays
have been detected to much, much higher energies.

~~~
kace91
the transition/duality of particles and waves is something that, despite
having heard about it many times, I'm still unable to grasp intuitively

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sathackr
I'm still not grasping it either, to the point that I feel we may eventually
learn they are neither, something else that looks to us sometimes like a
particle and sometimes like a wave.

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maxnoe
We already did learn that. QED describes a photon perfectly mathematically.

There is just now word that maps that to ordinary terms.

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maxnoe
Astrophysicist here, I'm currently finishing my PhD, mainly focused on data
analysis for the kind of telescopes that measured this GRB, while my main
focus is on a smaller prototype telescope (FACT), I also work for the one that
detected this GRB (MAGIC).

AMA ;)

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ajuc
Is there an archive with all the data ever received, or is the "uninteresting"
data dropped after some time?

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maxnoe
For the satellites all data is publicly available as required by NASA.

Unfortunately all ground based telescopes until now keep their data private
but nothing is thrown away ;) We have several Million air showers recorded.

This is going to change with the next gen observatory, which will operate as
an open observatory.

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rosybox
Are GRBs a danger to astronauts and people in the International Space Station?

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discordance
Are people on Earth safe from GRBs?

~~~
ncmncm
Depends on the GRB. A supernova 50 light years away is supposed to eliminate
all large animal life (including us). Fortunately any stars capable of it are
more than 100 Ly away, where they would only eliminate, e.g., civilization.

A magnetar quake 500 light years away would sterilize the planet (but not harm
the magnetar at all). Fortunately, the nearest magnetar we know about is 9000
light years away, so its blast would be ~300 times weaker, just enough for a
garden-variety mass extinction, and end of civilization. But there might be
one closer.

All the ones we detect happen millions of times farther away. So they are only
terrifying if you think about how we can even tell something happened that far
away.

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tannhaeuser
What about Eta Carinae?

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sanxiyn
We are probably okay. See "Superluminous supernovae: No threat from Eta
Carinae", [https://arxiv.org/abs/0705.4274](https://arxiv.org/abs/0705.4274)

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tejtm
>> A powerful outburst in a distant galaxy produced photons with high enough
energies to be detected by ground-based telescopes for the first time

First sentence makes no sense.

several galaxies produce photons with high enough energies to be detected by
ground-based mark-1 eyeballs every night.

Staggering numbers of galaxies produce photons with high enough energies to be
detected by ground-based telescopes every night.

They need to include the unusually short wavelength of the photons to convey
their message.

~~~
_ph_
Well, the sentence has to be understood in the context of the headline, which
specifically talks about gamma radiation, which so far was not possible to
observe from earth as the atmosphere absorbs it.

So this must have been a really scary event, sending photons over 4 billion
light years, energetic enough to pass through the absorbing atmosphere.

We can only hope to never be hit by a GRB from our cosmic neighbourhood, that
would be a life-ending event.

~~~
maxnoe
No gamma rays at these energies are able to penetrate the atmosphere and reach
the ground.

We only detect the particles indirectly.

When a high energy particle enters the atmosphere, it creates a cascade of
particles called an air shower. In that cascade, charged particles, mainly
electrons and positrons, travel faster than the speed of light in air and thus
produce Cherenkov radiation.

This is light in the UV to blue visible range, you may know it from pictures
of nuclear power plants.

The telescope measure the Cherenkov light and from that reconstruct the
properties of the particle that created the air shower.

This event was not the first time we measured high energy photons on the
ground, we do each night. But it was the first time we measured them from a
GRB.

