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On the viability of gravitational Bose–Einstein condensates as alternatives to supermassive black holes | Monthly Notices of the Royal Astronomical Society | Oxford Academic
“It is argued that astrophysical Bose–Einstein condensates (BECs) most likely form through a quasi-static contraction of ultradense cores of neutron stars. Such an evolutionary track would ensure that there is sufficient time left for the nuclear matter to stably liberate the excess of thermal energy, enable the core’s matter to intercommunicate and undergo a phase transition to form stellar BECs.”
theoreticalphysics  blackholephysics  boseeinsteincondensate  darkenergy  neutronstar  astrophysics 
october 2018 by danhon
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Scientists don't know what's causing this heat signature near a - via…
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september 2018 by Geek13
Colliding neutron stars could settle cosmology’s biggest controversy • Quanta Magazine
Natalie Wolchover on how measurements for the Hubble constant - how quickly the universe is expanding - might be determined; currently the two best estimates are 67 and 73 (the story explains the units that go with it):
<p>The crashing stars serve as “standard sirens,” as Holz and Scott Hughes of the Massachusetts Institute of Technology dubbed them in a 2005 paper, building on the work of Bernard Schutz 20 years earlier. They send rushes of ripples outward through space-time that are not dimmed by gas or dust. Because of this, the gravitational waves transmit a clean record of the strength of the collision, which allows scientists to “directly infer the distance to the source,” Holz explained. “There is no distance ladder, and no poorly understood astronomical calibrations. You listen to how loud the [collision] is, and how the sound changes with time, and you directly infer how far away it is.” Because astronomers can also detect electromagnetic light from neutron-star collisions, they can use redshift to determine how fast the merged stars are receding. Recessional velocity divided by distance gives the Hubble constant.

From the first neutron-star collision alone, Holz and hundreds of coauthors calculated the Hubble constant to be 70 kilometers per second per megaparsec, give or take 10. (The major source of uncertainty is the unknown angular orientation of the merging neutron stars relative to the LIGO detectors, which affects the measured amplitude of the signal.) Holz said, “I think it’s just pure luck that we’re smack in the middle,” between the cosmic-distance-ladder and cosmic-microwave-background Hubble estimates. “We could easily shift to one side or the other.”

The measurement’s accuracy will steadily improve as more standard sirens are heard over the next few years, especially as LIGO continues to ramp up in sensitivity. According to Holz, “With roughly 10 more events like this one, we’ll get to 1 percent [of error],” though he stresses that this is a preliminary and debatable estimate.</p>


If we can fix the Hubble constant, we might have an idea of the composition of the universe. Then again, we might just be more confused about the differences between the early one, and the current one.
astronomy  neutronstar  hubble 
october 2017 by charlesarthur
Twitter
Terminology note:
- collision produced
- When viewing in optical, called a , l…
kilonova  GammaRayBurst  NeutronStar  from twitter_favs
october 2017 by dalcrose
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Terminology note:
- collision produced
- When viewing in optical, called a , l…
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october 2017 by Geek13
Twitter
Terminology note:
- collision produced
- When viewing in optical, called a , l…
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october 2017 by judson
Twitter
RT : The collision was seen in basically every wavelength of light we observe, & . Amazi…
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october 2017 by jaxzin
Twitter
The collision was seen in basically every wavelength of light we observe, & . Amazi…
GravitationalWaves  NeutronStar  from twitter_favs
october 2017 by dalcrose

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