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Thread: GRB 130427A - burst of the (quarter) century

  1. #61
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    Thanks for the magnetar info.!

  2. #62
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    Well, in a strongly variable source, why should you not determine a peak luminosity with as much accuracy as possible? This gives more interesting constraints on the involved physics than just smearing everything out.

    Reports are coming in concerning the advent of the supernova.

    - I myself observed on Sunday and could not find any significant evidence yet for a slowing of the decay.
    - Xu et al. report on continuous observations with the Nordic Optical Telescope on La Palma, claiming a clear flattening on Sunday and Monday and a change in the Spectral Energy Distribution, from a power-law (afterglow) to a roughly thermal source peaking in the optical (supernova).
    - Garnavich has acquired a spectrum with the Large Binocular Telescope and finds NO spectroscopic evidence for a SN yet.
    - Butler and colleagues have been observing the afterglow with the new RATIR detector on a 1.5m telescope in Mexico and their newest data (up to last night) also do NOT show any evidence for a SN yet.
    EDIT: - Perley & Tang now also report Keck LRIS photometry and spectroscopy. No evidence of a SN in either (photometry is a straight extrapolation of the earlier decay).

    So it's confusing right now.
    Last edited by Don Alexander; 2013-May-09 at 06:38 PM. Reason: Added new info

  3. #63
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    Thank you very much Don Alexander! This is the interesting thing I like to see.

  4. #64
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    it's more like that GRB 060614 which too had no supernova..So is there any update on 130505A? it was more powerful than 27A but no one has any signfcant interest in analyzng its optical properties. If supernovas are not enough to explain the grbs then perhaps some mechanism like collision of clouds of matter-antmatter or some black hole disrupting other neutron star or normal star could be responsible for such explosions. Have Supernovae been detected from all the long grbs so far? But sometimes a delay of about 1/2 months occurs between the supernova and the gamma ray burst, and as long as we can not find overabundance of elements generally dispersed in a core-collapse supernova explosion we can't be sure of grb's supernova connection. So we prefer the collapsar model of GRbs , but is it because it provides provides a theoretical framework for this grb-sne connection? And is there no evidence for a black hole induced accretion event which might cause a long GRb e.g., a black hole destroyng a star kind of something/do all the evidences favour collapsar origin?
    Last edited by Only1Indrajit; 2013-May-13 at 02:56 AM.

  5. #65
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    Quote Originally Posted by Only1Indrajit View Post
    it's more like that GRB 060614 which too had no supernova..
    Except, of course, for being two orders of magnitude more energetic, significantly more distant, having a much brighter afterglow and a much brighter host galaxy, all of which make the discovery of the supernova more difficult.
    And anyway, it has been discovered, see below.
    Quote Originally Posted by Only1Indrajit View Post
    So is there any update on 130505A? it was more powerful than 27A but no one has any signfcant interest in analyzng its optical properties.
    It was the same with GRB 030328, a bright GRB with a bright (but nowhere exceptional) afterglow which had the "bad luck" of happening a day before 030329...
    Quote Originally Posted by Only1Indrajit View Post
    If supernovas are not enough to explain the grbs then perhaps some mechanism like collision of clouds of matter-antmatter or some black hole disrupting other neutron star or normal star could be responsible for such explosions.
    Irrelevant speculation, not needed. Anyway, a (stellar-mass) black hole disrupting a neutron is actually one of the viable models for SHORT GRBs. Where no SN is expected. And none have been detected.
    Quote Originally Posted by Only1Indrajit View Post
    Have Supernovae been detected from all the long grbs so far?
    Of course not, most are too far away to allow even modern Big Glass to detect the SN without using incredible amounts of observing time in the NIR. The only two events where people resonably expected to see a SN where none was found are 060505 and 060614.
    Quote Originally Posted by Only1Indrajit View Post
    But sometimes a delay of about 1/2 months occurs between the supernova and the gamma ray burst,
    There is no evidence for such a time offset. SNe generally take roughly two weeks to rise to peak, at early times, the afterglow is way brighter (and the host usually too) to be able to separate the SN component. In cases where the afterglow has been non-existent, like 980425 or 060218, the SN has been detected within days, and for 060218, an ultraviolet shock-breakout flash preceded it which is also a SN characteristic which is rarely observed.
    Quote Originally Posted by Only1Indrajit View Post
    and as long as we can not find overabundance of elements generally dispersed in a core-collapse supernova explosion we can't be sure of grb's supernova connection.
    Are you seriously implying the detection of SNe, either photometrically or even spectroscopically, in pretty much all GRBs which have been followed up up to z ~ 0.5 or so, each occurring within the weeks after the GRB, at the exact location within the astrometrical errors, is not enough to convince you?? Not to mention what evidence would your suggestion add? Those elemental abundances would be produced by an SN even if it was not associated with the GrB and be a pure chance alignment.
    You seem to be ignoring almost all available evidence and fabricating baseless claims.
    Quote Originally Posted by Only1Indrajit View Post
    So we prefer the collapsar model of GRbs , but is it because it provides provides a theoretical framework for this grb-sne connection?
    One of the basic tenets of science is that theories must be supported by observational evidence. If you have a theory, and it is supported by observations, likely the theory is correct (of course, new and better observations may come along and invalidate it, that is the way of science). What you are saying here makes no sense, it sounds like we should distrust the collapsar model because it is able to explain the observations. I mean, in essence, your sentence is absolutely correct. but the statement should be that since it explains the GRB-SN connection, of course the collapsar model is the standard model for GRB progenitors. There is no "but" involved.
    Quote Originally Posted by Only1Indrajit View Post
    And is there no evidence for a black hole induced accretion event which might cause a long GRb e.g., a black hole destroyng a star kind of something/do all the evidences favour collapsar origin?
    GRBs are black hole accretion events. Within a star. What you refer to in the latter part is a so-called tidal disruption flare. GRB 110328/SwJ1644 was the first example of a relativistic TDF, and it indeed triggered Swift, but it looks very different from a typical GRB, both at high energies and in terms of "afterglow". Also, no SNe are expected to accompany such events.

    So, anyway!

    After quite some confusion, the SN has finally been detected spectroscopically by de Ugarte Postigo et al. using the 10.4m GTC on La Palma: http://gcn.gsfc.nasa.gov/gcn3/14646.gcn3 Additionally, this has just now been issued as a CBET, the IAU designation for the SN is SN 2013cq. Also, the SN seems to be rising photometrically as well, see http://gcn.gsfc.nasa.gov/gcn3/14662.gcn3 and http://gcn.gsfc.nasa.gov/gcn3/14666.gcn3 The situation here is less clear, though, as disentangling afterglow, host and SN is going to be very troublesome.

  6. #66
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    Additionally (had to split it in two, post got too long), I have a public service message.

    In Italy, following a press release by none other than the Ministry for Education, University and research, it is being breathlessly claimed that Italian researchers, for the first time EVER, have predicted the explosion of a supernova in advance. This press release is a farce and a slap in the face of the greater GRB community.

    As I have explained in this thread, the association between "long" GRBs and SNe has been established since a decade (and was strongly suspected for another 5 years before that). Furthermore, both the GRB and the SN are produced by the core collapse of the massive star. It's just that we see the GRB essentially immediately, whereas the peak of the SN comes weeks later. The combination of these well-grounded facts is that whenever a long GRB occurs, everyone knows that an SN just occurred as well. Then, if spectroscopy shows this GRB to be at a reasonably low redshift (say, 0.7 or lower), and observability allows it, it is generally a given that the late light curve will be followed up at least photometrically, and possibly spectroscopically. In the case of 130427A, the brightest GRB in years, you could "bet your sweet biffy" everyone with access to Big glass would be all over this one pretty much from day one.
    Now it is true that Ruffini et al. published a GCN which predicted the SN to occur. But...
    a) "The late x ray observations of GRB 130427A by Swift-XRT clearly evidence a pattern typical of a family of GRBs associated to supernova (SN) following the Induce Gravitational Collapse (IGC) paradigm (Rueda & Ruffini 2012; Pisani et al. 2013)." This group has an ATM model for GRBs (well, a lot less ATM than something like EU or the Reptoid Conspiracy, but ATM vs the collapsar/fireball model) and they recently claimed some discovery of some pattern... I'm not sure what it entails, but the main point is that the collapsar model (and also the cannonball model of Dado, Dar and De Rujula) always predicts an SN to follow a long GRB. There is nothing special about this prediction at all. Which is why...
    b) no one else actually put it in writing, since it was so blazingly obvious. It's like seeing nearby lightning and shouting "We will hear thunder in some seconds!!" and when the thunder does come, writing a ministerial press release that you successfully predicted a thunderclap.

    Furthermore, several statements in the press release are pretty much blatant falsehoods.
    - The general "supernova prediction" is already a falsehood. As just stated, the GRB is a part of the SN, and therefore, the GRB itself is the alert for the SN. Ruffini in no way predicted the GRB to occur, their GCN came five days after the event, when they knew the spectroscopic redshift and everything. The SN had already occurred five days beforehand, yet they make it out to be a true prediction.
    - "The Italian scientific insight was to understand the relationship between the gamma-ray burst (GRB) and trigger the explosion of Supernova (Induced Gravitational Collapse - IGC)." As if no other GRB model predicted an SN to follow a GRB...
    - "Prof. Ruffini and his group have alerted all observers." Yeah, see my statement above. If Ruffini had not put out that GCN, absolutely no one would not be following up the SN right now.
    - "It is the first time in the history of Astronomy and Astrophysics that is able to predict a similar phenomenon." This one is the "mother" of it all. Now, to my very best knowledge, yes, no one has ever pointed to a "known" star (say, in the Milky Way or the Magellanic Clouds) and stated: "This star will explode as an SN in two weeks." and then it went off (of course, we know loads of stars that will go SN "in the next 100000 or 1 Million years"...). But, as mentioned above, GRB, known redshift, etc. And then, beyond THAT, even in terms of "We see a nearby GRB and predict it will be followed by an SN.", this is in no way the first time this has ever been done.
    "Predicting" SN 2003dh which followed GRB 030329, already ten years ago.
    Dado, Dar & De Rujula predicting SN 2003dh as well.
    Even beforehand, they did it for GRB 011121.
    Dado & Dar on the SN following GRB 090618.
    In all these case, SNe were detected more or less in the way their behavior was predicted.
    - "The phenomenon actually occurred 10 billion years ago in the primordial stages of the Universe, was observable only last night, in the direction of the constellation Leo, the explosion because the light took 10 billion years to reach the earth. This phenomenon has happened so many as 5 billion years before the birth of our solar system." At a redshift of 0.3399, the light-travel time (I confess I'm not 100% sure that is identical to the lookback time, but it must be close) is 3.75 gigayears, for sure a large number, but nowhere near the "primordial Universe" or "5 billion years before the formation of the Earth."

    And I'm not even going to comment on the last paragraph. It would just be too political for this forum.

    I sincerely hope other Italian GRB scientists will speak out against this , to put it mildly, assortment of dire misinformation.

    I hope I don't get into trouble with this, but my scientific honor has been really wounded.
    Last edited by Don Alexander; 2013-May-16 at 08:59 PM.

  7. #67
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    The Italians are also predicting that the pope will die in his lifetime.

  8. #68
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    And now, for some papers!

    So, some time has passed, and this GRB has been generating intense interest in the community and a lot of research has been published already!!

    Here's a selection of papers dealing with the burst:

    The first few papers used the publicly available Fermi data to study high energy processes. For certain reasons, we call these "Chinese theory papers".

    Yi-Zhong Fan et al.: High energy emission of GRB 130427A: evidence for inverse Compton radiation http://arxiv.org/abs/1305.1261
    Pak-Hin Thomas Tam et al.: Discovery of an extra hard spectral component in the high-energy afterglow emission of GRB 130427A http://arxiv.org/abs/1305.3217
    Ruo-Yu Liu et al.: Interpretation of the unprecedentedly long-lived high-energy emission of GRB 130427A http://arxiv.org/abs/1307.5338

    A further highly theoretical paper was triggered by the IceCube (non-)results:

    S. Gao et al.: On the neutrino non-detection of GRB 130427A http://arxiv.org/abs/1305.6055

    From the observational side, two papers deal with the supernova so far, one presenting the photometric/spectroscopic discovery, and one HST observations:

    D. Xu et al.: Discovery of the broad-lined Type Ic SN 2013cq associated with the very energetic GRB 130427A http://arxiv.org/abs/1305.6832
    A. J. Levan et al.: Hubble Space Telescope observations of the afterglow, supernova and host galaxy associated with the extremely bright GRB 130427A http://arxiv.org/abs/1307.5338

    The early radio afterglow has been found to contain some interesting features:

    T. Laskar et al.: A Reverse Shock in GRB 130427A http://arxiv.org/abs/1305.2453

    Finally, this paper (which is especially close to my heart for certain reasons...) presents a vast broadband observation campaign and modelling of the afterglow over 16 decades in energy. The main result is the the GRB is boring!

    D. A. Perley et al: The Afterglow of GRB 130427A from 1 to 10^16 GHz http://arxiv.org/abs/1307.4401

    Enjoy!

  9. #69
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    More papers!

    So!!

    After a looong wait, the Science papers have appeared online. Sorry for this, but the first two are not yet out on astro-ph, therefore I'm just linking to Science right now, but the full articles are behind a paywall...

    Ackermann et al.: Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A http://www.sciencemag.org/content/ea...42353.abstract

    Preece et al: The First Pulse of the Extremely Bright GRB 130427A: A Test Lab for Synchrotron Shocks http://www.sciencemag.org/content/ea...42302.abstract

    Maselli et al.: GRB 130427A: a Nearby Ordinary Monster http://arxiv.org/abs/1311.5254

    Vestrand et al.: The Bright Optical flash and Afterglow from the Gamma-Ray Burst GRB 130427A http://arxiv.org/abs/1311.5489

    Kouveliotou et al: NuSTAR Observations of GRB130427A establish a single component synchrotron afterglow origin for the late optical to multi-GeV emission http://arxiv.org/abs/1311.5245

    So far, I've read everything except the Supplement of Maselli et al. and the Kouveliotou paper (which was also submitted to Science but rejected...). My first impression is: Yeah, great data, but I don't see anything of high impact. The Preece paper, I think, presents the most novel data so far, but it is really specialized and feels displaced in such a journal. Ackermann et al. and Vestrand et al. are good papers, but again, other GRBs in the past have shown similar results, partially with even better data (e.g., GRB 080319B in the optical). The Maselli paper, well, I should not pronounce final judgment until I have read the SM, but it presents a very different model from Perley et al. (see post above - this was accepted a few days ago with minor changes, by the way) and also Vestrand et al. (as well as a paper by Panaitescu et al. in MNRAS which seems kind of an expanded copy of the Vestrand paper...), generally doing so by ignoring large amounts of data from other publications, especially in the radio.

  10. #70
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    Thanx for the update!

  11. #71
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    The last two missing Science papers are out on astro-ph!

    Ackermann et al.: Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A http://arxiv.org/abs/1311.5623

    Preece et al: The First Pulse of the Extremely Bright GRB 130427A: A Test Lab for Synchrotron Shocks http://arxiv.org/abs/1311.5581

    And here is also the Panaitescu paper I mentioned in my last post:

    A. Panaitescu et al: An external-shock model for GRB afterglow 130427A http://arxiv.org/abs/1311.5867

    And finally, as a bonus, a paper on the prompt emision of the most peak-luminous GRB ever detected:

    D. Frederiks et al: The ultraluminous GRB 110918A http://arxiv.org/abs/1311.5734

  12. #72
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    Quote Originally Posted by Ackermann
    In the standard model of GRBs, the blast wave that produces the initial, bright prompt emission later collides with the external material surrounding the GRB (the circumburst medium) and creates shocks... Until this burst, the high-energy emission from LAT-detected GRBs had been well described by this model, but GRB 130427A challenges this widely accepted model...

    ...The LAT observations of GRB 130427A challenge the scenario in which the GeV photons are nonthermal synchrotron radiation...The presence of high-energy photons at times t ≫ tdec is incompatible with these γ rays having a synchrotron origin...
    There goes the sychrotron death ray I was hoping to perfect by Christmas!

    Seriously; these beasts, and there have been a half dozen of the now; wreak havoc on models that were just starting to make sense. Does it make any sense to talk about these events in terms of beaming? Beaming drastically cuts down the total energy necessary, but at the expense of a mechanism that is incredibly timing-sensitive. Since we have new (unbounded?) boundaries on total energy; should the beamed models that were motivated to keep the total energy well below these values be scrapped?

  13. #73
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    I don't see the connection?? Are you confusing the total energy release with the maximum energy within single photons? The LAT paper is discussing the latter. This has nothing to do with collimation and beaming, but with Fermi acceleration.

    Anyway, I personally thought the LAT paper was riding the "these photons can't be explained by a synchrotron afterglow" horse a bit too hard. Even assuming their argument is correct, several things remain a bit hidden in the discussion:

    - Saying that the standard model can't explain these photons is not saying the standard model fails at explaining afterglows in general! Everything but these very high-energy photons is explained just fine.
    - a process such as magnetic reconnection can produce these photons even from an afterglow, it's just that "standard model" implies Fermi acceleration. Kouveliotou et al. make this point much better.
    - Panaitescu et al. show that the additional high-energy photons (and the LAT paper shows a hardening at high energies) can be explained by an inverse Compton component, which would naturally follow the afterglow evolution. In their analysis all of it IS afterglow, just not all is die to a synchrotron spectrum.

  14. #74
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    We seem to be finding more and more of this stuff
    NASA telescope designed to find exoplanets captures gamma-ray burst
    https://www.upi.com/Science_News/202...3501619810056/

    TESS Detects Bright, Long-Lasting Gamma-Ray Burst
    http://www.sci-news.com/astronomy/te...rst-09621.html

    "Our findings prove this TESS telescope is useful not just for finding new planets, but also for high-energy astrophysics," said Smith, who specializes in using satellites like TESS (Transiting Exoplanet Survey Satellite) to study supermassive black holes and gas that surrounds them. Such studies shed light on the behavior of matter in the deeply warped spacetime around black holes and the processes by which black holes emit powerful jets into their host galaxies.

    Smith calculated that GRB 191016A had a peak magnitude of 15.1, which means it was 10,000 times fainter than the faintest stars we can see with the naked eyes.
    I wonder if I should start a new topic on GRBs?

  15. #75
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    Quote Originally Posted by Launch window View Post
    We seem to be finding more and more of this stuff
    NASA telescope designed to find exoplanets captures gamma-ray burst
    https://www.upi.com/Science_News/202...3501619810056/

    TESS Detects Bright, Long-Lasting Gamma-Ray Burst
    http://www.sci-news.com/astronomy/te...rst-09621.html

    I wonder if I should start a new topic on GRBs?
    Probably worthwhile since this thread is a) kinda old and b) is about a specific GRB.

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