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Space Science

Space Scientists Reveal Brightest Gamma Explosion Ever (bbc.co.uk) 37

Posted by EditorDavid from the gamma-gamma-hey dept.
It was 10 times brighter than any previously detected, reports the BBC, noting it illuminated much of the galaxy.

RockDoctor (Slashdot reader #15,477) writes: A recent paper on ArXiv describes a Gamma Ray Burst (GRB) whose light arrived late last year as one of the strongest ever observed. GRB 221009A was detected on October 9 last year (yes, that number is a date), so 5 and a bit months from event to papers published is remarkably quick, and I anticipate that there will be a lot more papers on it in the future. Stand-out points are :


- it lasted for more than ten hours after detection (a space x-ray telescope had time to orbit out of the Earth's shadow and observe it)
- it could (briefly) be observed by amateur astronomers.
- it is also one of the closest gamma-ray bursts seen and is among the most energetic and luminous bursts.


It's redshift is given as z= 0.151, which Wikipedia translates as occurring 1.9 billion years ago, at a distance of 2.4 billion light-years from Earth.

Observations have been made of the burst in radio telescopes (many sites, continuing), optical (1 site ; analysis of HST imaging is still in work), ultraviolet (1 space telescope), x-ray (2 space telescopes) and gamma ray (1 sapce telescope) — over a range of 1,000,000,000,000,000-fold (10^15) in wavelength. It's brightness is such that radio observatories are expected to continue to detect it for "years to come".

The model of the source is of several (3~10) Earth-masses of material ejected from (whatever, probably a compact body (neutron star or black dwarf) merger) and impacting the interstellar medium at relativistic speeds (Lorentz factor 9, velocity >99.2% of c). The absolute brightness of the burst is high (about 10^43 J) and it is made to seem brighter by being close, and also by the energy being emitted in a narrow jet ("beamed"), which we happen to be near the axis of.

General news sites are starting to notice the reports, including the hilarious acronym of "BOAT — Brightest Of All Time". Obviously, with observations having only occurred for about 50 years. we're likely to see something else as bright within the next 50 years.

The brightness of the x-rays from this GRB is such that the x-rays scattered from dust in our galaxy creates halos around the source — which are bright enough to see, and to tell us things about the dust in our galaxy (which is generally very hard to see). Those images are more photogenic than the normal imagery for GRBs — which is nothing — so you'll see them a lot.
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Space Scientists Reveal Brightest Gamma Explosion Ever More

Space Scientists Reveal Brightest Gamma Explosion Ever

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  • GRB 221009A was detected on October 9 last year (yes, that number is a date)

    Funny how Y2K just keeps going and going.

    • Forget Y2K. How did an event occur 1.9b years ago 2.4b ly away and we observe it? Rama rays dont travel faster than light do they?

      • I guess the object kept moving for 1.9b years before the we detected the burst.

        • But we would see where it was not where it is?

          • But we would see where it was not where it is?

            Wikipedia explains it better [wikipedia.org] than TFA.

            It was 1.9B ly from Earth when the burst occurred, and that is what we observe.

            The redshift tells us the velocity, which means it is now 2.4B ly from Earth.

            If such a GRB occurred in the Milky Way, it would wipe out life on Earth. It would sterilize the galaxy.

        • Re: Y2K (Score:4, Informative)

          by RockDoctor ( 15477 ) on Saturday April 01, 2023 @10:03PM (#63418000) Journal
          That is correct. The light was emitted 1.9 billion years ago, and in that travel time (the "look-back time) the expansion of the universe has move the source about half a billion light years further away from us. The distance is the "co-moving distance [wikipedia.org]".

          The next question is to the effect that "doesn't that require you to have a cosmological model for how expansion rates change with time, universe density etc?" To which the answer is, "Yes, and the details of the model used are in the ArXiv paper cited." I don't remember what the details were, but I do know that they weren't the "Planck mission best estimates" which I used when making my own redshift/ co-moving distance/ lookback time tool a few weeks ago.

      • Re: Y2K (Score:5, Informative)

        by Joce640k ( 829181 ) on Saturday April 01, 2023 @05:15PM (#63417614) Homepage

        Forget Y2K. How did an event occur 1.9b years ago 2.4b ly away and we observe it? Rama rays dont travel faster than light do they?

        Astronomy 101: The universe is expanding.

        • Equally from all places/points at the same time?

          • Yes.

            I really wish I believed you intended to end that sentence with a period.

          • Yes, in fact there is still an energy (dark energy) trying to push every point away from each other, like a blueberries in a muffin move away from each other. The blueberries themselves stay intact because the forces holding the blueberry together are strong. Most galaxies are accelerating away from each other (with exceptions on local scales).

            • This is why your choice of cosmological model (in particular, the ratio of gravitating mass to "dark energy") is important when trying to convert a redshift measurement into an estimate for lookback time and comoving distance.
      • You have to be careful with how you define distances in an expanding universe. The light has traveled 1.9B light years, but due to the expansion its now 2.4B light years away. Cosmologists of course understand all this and the terminology is clear
        • But how do you know that? The light is telling us about the state as it was (presumably prior to expansion since it was emitted). We also should not know where it is now because that info hasnt reached us yet either. How can we know about the expansion if the light of that expansion is en route still?
          • If you assume (as is believed to be true) that shifts in spectral lines are entirely due to the expansion of the universe, you can used the redshift of the lines to determine how distant the object was when it emitted the light. This leaves an unknown scale in the problem. Then things like supernova whose brightness is believed to be known can be used to help figure out the absolute distance

            Its all hard (cosmology is hard, who knew...). See https://en.wikipedia.org/wiki/... [wikipedia.org] and https://en.wikipedia. [wikipedia.org]
            • I see how that can be inferred, I was having trouble wrapping my head around how to know the distance has expanded. The redshifting article explains in a way that I think I get. We don't really know but can infer.
  • How can something be seen here on earth that occurred 1.9 billion years ago but is 2.4 billion light years distant? I suppose the reason is that 500 million years ago it was closer to us, or around 1.9 billion light years away. Maybe a bit closer since the ejected material was traveling 99.2% of c.
    • Because the universe is expanding.

    • How can something be seen here on earth that occurred 1.9 billion years ago but is 2.4 billion light years distant? I suppose the reason is that 500 million years ago it was closer to us, or around 1.9 billion light years away.

      Yes.

  • Don't tell me the simulation uses NTSC.

    • [slow hand clap dot GIF]

      You do realise that if you make this joke 3 times in a month, your TV will switch emission from the visible spectrum to MeV gamma rays?

  • Is a space scientist like an astronomer? Maybe that word has too many syllables for the average Joe...

    • The term of "Space Scientist" includes several distinct (albeit somewhat overlapping) occupations.
      An astronomer is not exactly the same thing as an astrophysicist, for example. An aerospace engineer is also a space scientist, but different from the two aforementioned examples.

      Think of the term "IT specialist" - it encompasses many different jobs and specializations.

    • My first thought too. But ultimately i knew i should just shut up and trust the experts. If you'll excuse me I have to get back to by birthing person.

    • Astronomers are space scientists.

      So are rocket scientists.

      Geologists (my paying work, look at the username) who are interested in geological processes on other planets (particularly Mars and Venus, with atmospheres quite like ours) often self-identify as "planetary scientists" (because in Greek, "ge-" relates to "Gaia", the Titanic goddess embodying the Earth, and "Areologist" and "Venerologist" just gets clumsy for overlapping fields.

      I've not heard of specialists in gas giants, "ice giants", or the "sma

  • LIGO [caltech.edu] will likely have picked it up already. When they publish is going to be very interesting and telling of exactly what is happening.
  • That was a safe bet.

    I'm still ploughing through my backlog, but I note : "LIMITS ON NEUTRINO EMISSION FROM GRB 221009A [arxiv.org]"

    Abstract :

    Gamma-ray bursts (GRBs) have long been considered a possible source of high-energy neutrinos. [...] the recent observation of GRB 221009A â" the brightest GRB observed [...] â" provides a unique opportunity to test for hadronic emission. In this paper, we leverage the wide energy range of the IceCube Neutrino Observatory to search for neutrinos from GRB 221009A.

    Annn

  • I was looking through my web history, wondering if I searched for something related, maybe 'dizziness' or 'headache' while the GRB was happening and I found I searched for an episode of BBC Horizons "The Death Star" that day and also did some reading on Stirling Colgates satellites. An interesting coincidence.
    Be interesting to see if there were increased reports of headaches or dizziness during that time period.

  • Summary speculates the compact body could have been a black dwarf, but these do not exist (and won't for about a quadrillion years).

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