Gravitational waves detected from colliding neutron stars.

Discussion in 'Astronomy, Exobiology, & Cosmology' started by sweetpea, Oct 16, 2017.

  1. sweetpea Registered Senior Member

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  3. Michael 345 Valued Senior Member

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    NT News Darwin today 18 Nov 17

    Anybody got the spare change and time to go and collect a Earth size nugget of gold?

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  5. paddoboy Valued Senior Member

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    Yes great news sweetpea! I'm rather surprised more havn't commented on it. The detection of gravitational radiation from colliding/merging Neutron stars actually is far more exciting and news worthy, particularly since it was also detected in the EMR range.
    Here's some more info on it......
    https://www.universetoday.com/13762...st-gravitational-wave-observed-independently/
    “This is quite literally a physics gold mine!” said Masao Sako, with the University of Pennsylvania.

    For over a week now, the astronomy and astrophysics communities have been buzzing with the news of the latest gravitational wave discovery. And this discovery has been big.

    Four days before the Great American Solar Eclipse on August 21, a newly discovered gravitational wave caused more astronomers (8,223+), using more telescopes (70), to publish more papers (100 — see the list below) in less time than for any other astronomical event in history. The sixth gravitational wave (GW) to be discovered by the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo GW observatories, which occurred on August 17, 2017 at 12:41:04 UTC, was surprising in two ways already reported.

    GW event six, designated GW170817, did not result from the collision and subsequent explosion of two black holes. All previous GW events, including the first ever discovered in 2015, had involved the collision of black holes with typically 40 times the mass of the Sun between them. Here however, the GW was evidently triggered by the collision and explosion of two neutron stars, having only 3 times the Sun’s mass in total".

    "Crucially, GW170817 occurred ten times closer to Earth than all earlier GW events. Earlier GWs involved black hole collisions at more than 1.3 billion light-years (400 million parsecs or Mpc). GW170817, in comparison, was known within hours of its discovery to lie within only 130 million light-years (40 Mpc). That vastly improved astronomer’s odds of detecting the event independently, because in cosmological terms, it occurred within less than 1% of the universe’s Hubble length of 14 billion light-years (4,300 Mpc).

    Not widely reported is that our current astronomical theory regarding GW170817 still depends significantly on observations yet to be made. In brief, astronomers currently believe that GW170817 was triggered by the merger of two neutron stars, which triggered the explosion of a Short Gamma-Ray Burst (SGRB), which emitted only a fraction of the gamma-ray energy in our direction normally associated with SGRBs, because it was the first SGRB observed at such a large angle away from the direction of its focused jets of gamma-rays. The SGRB associated with GW170817 emitted its jet at roughly 30 degrees away from our line-of-sight. All other SGRBs have been observed at only a few degrees from alignment with their jets. The exact angle of the newly discovered SGRB’s jet is important in understanding how its afterglow compares with other SGRB afterglows. Significant properties reported for the GW, including its distance, depend on the angle at which the two neutron stars collided relative to Earth".
    excerpt:
    EVENT CHRONOLOGY

    T = 0 sec.: GW170817 detected by LIGO/VIRGO [1, 82]
    T = 1.74 sec.: SGRB 170817A detected by Fermi Gamma-Ray Burst Monitor satellite immediately after GW170817 [52]
    T = 28 min.: Gamma-ray Coordinates Network (GCN) Notice [53]
    T = 40 min.: GCN Circular [53]
    T = 5.63 hr.: First sky map locating GW170817 to within several degrees [53]
    T = 10.9 hr.: Swope 1-m observatory discovers explosion’s afterglow, AT 2017gfo, in galaxy NGC 4993 [18, 24, 64, 75, 77]
    T = 11.09 hr.: PROMPT 0.4m observatory detects AT 2017gfo [88]
    T = 11.3 hr.: Hubble Space Telescope images AT 2017gfo [20]
    T = 12-24 hr.: Magellan; Las Campanas Observatory; W. M. Keck Observatory; Blanco 4-m Cerro Tololo Inter-American Observatory; Gemini South; European Southern Observatory VISTA; Subaru among 6 Japanese telescopes; Pan-STARRS1; Very Large Telescope; 14 Australian telescopes; and Antarctic Survey Telescope optical observatories, and VLA, VLITE, ATCA, GMRT, and ALMA radio observatories, as well as Swift and NuSTAR ultraviolet satellite observatorie
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    Much more at the link.

    And of course the aLIGO site itself at...
    https://www.ligo.caltech.edu/page/about-aligo
     
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  7. paddoboy Valued Senior Member

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    Questions arising from this Neutron binary merger.....
    (1) Has the remant of the collision/merger, resulted in a BH? ( further research should validate this one way or the other....
    (2) It is often hypothesised that deep within a Neutron star, we would have Quark matter: Again further study and data from other mergers, could also give us insight to this hypothesis.
    ( And of course heavy element nucleosynthesis.
    As one of our friends in the article exclaimed, a literal gold mine of knowledge to be had!
     

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