First Light from a Gravitational Wave Event (GW170817)

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First Light from a Gravitational Wave Event (GW170817)

Post by bystander » Mon Oct 16, 2017 2:25 pm

NASA Missions Catch First Light from a Gravitational-Wave Event
NASA | Chandra | JPL-Caltech | Hubble | Spitzer | Swift | Fermi | 2017 Oct 16

Radio “Eyes” Unlocking Secrets of Neutron-Star Collision
National Radio Astronomy Observatory | 2017 Oct 16

Merging Neutron Stars Scatter Gold & Platinum into Space
European Southern Observatory | 2017 Oct 16

Hubble Observes Source of Gravitational Waves for the First Time
ESA Hubble Science Release | 2017 Oct 16

Hawaii Astronomers Help Reshape Our Understanding of the Universe
University of Hawaii | Institute for Astronomy | 2017 Oct 16

Australians Confirm Radio Emission from Gravitational Wave Event
University of Sydney | 2017 Oct 16

MeerKAT Contributes to International Collaboration & Major Discovery
Square Kilometer Array, South Africa | 2017 Oct 16

Astronomers See Light Show Associated with Gravitational Waves
Harvard Smithsonian Center for Astrophysics | 2017 Oct 16

Gravitational Waves Detected for First Time from Two Stars Colliding
Australian National University | 2017 Oct 16

Gravitational Waves Shed First Light on Mergers of Neutron Stars
French National Center for Scientific Research | 2017 Oct 16

Astronomers Feast on First Light from Gravitational Wave Event
Gemini Observatory | 2017 Oct 16

Astronomers First to See Source of Gravitational Waves in Visible Light
Dunlop Institute of Astronomy & Astrophysics | Toronto University | 2017 Oct 16

Global Telescope Network Catches Fleeting Kilonova for the First Time
Las Cumbres Observatory | 2017 Oct 16

First Observations of Merging Neutron Stars Mark New Era in Astronomy
University of California, Santa Cruz | 2017 Oct 16

Caltech-Led Teams Strike Cosmic Gold
California Institute of Technology | 2017 Oct 16

Scientists Detect Light from Gravitational Waves Event
Universities Space Research Association | 2017 Oct 16

First detection of gravitational waves produced by colliding neutron stars
National Science Foundation | LIGO/Virgo Collaborations | 2017 Oct 16

Cosmic Forge of Rare Heavy Elements Discovered
National Optical Astronomy Observatory | 2017 Oct 16

A new era of astronomy begins with first observation of neutron star merger
Carnegie Institution for Science | 2017 Oct 16

Astronomers Strike Cosmic Gold with Neutron Star Merger
University of California, Berkeley | 2017 Oct 16

ALMA and About 70 Observatories to Probe for LIGO-Virgo’s Gravitational Waves Detection
ALMA Observatory | 2017 Oct 16

Gamma-Ray Burst & Visible Afterglow Seen with Gravitational Waves
Max Planck Institute for Extraterrestrial Physics | 2017 Oct 16

Gravitational Waves & Light Reveal Merger of Two Neutron Stars
Max Planck Institute for Astrophysics | 2017 Oct 16

Researchers Usher in Era of Multimessenger Astronomy with LIGO Discovery
Rochester Institute of Technology | 2017 Oct 16

Astronomers Detect Colliding Neutron Stars for First Time
Northwestern University | 2017 Oct 16

Crashing Neutron Stars Unlock Secrets of the Universe
Science & Technology Facility Council, UK | 2017 Oct 16

Gravitational waves + new clues from space reveal new way to make a black hole
Penn State University | 2017 Oct 16

Scientists reveal first light from stellar collision discovered by gravitational waves
University of Leicester | 2017 Oct 16

Researchers Detect Gravitational Waves from Colliding Neutron Stars
University of Washington | 2017 Oct 16

Team Supports Detection of Light from Gravitational-Wave Source
Arizona State University | 2017 Oct 16

28 Years Later, LIGO Confirms 1989 Hebrew University Prediction
Hebrew University of Jerusalem | 2017 Oct 16

Gravitational Waves Detected Following Collision of Neutron Stars
American Friends of Tel Aviv University | 2017 Oct 16

Scientists Spot Explosive Counterpart of LIGO/Virgo's Latest Gravitational Waves
Fermi National Accelerator Laboratory | 2017 Oct 16

Latest Gravitational-Wave Detection Opens New Era for Astronomy
McGill University | 2017 Oct 16

Gamma-Ray Burst Detection Just What Researchers Predicted
Oregon State University | 2017 Oct 16

LIGO & Virgo Detect Gravitational Waves from Colliding Neutron Stars
West Virginia University | 2017 Oct 16

Integral Sees Blast Travelling with Gravitational Waves
ESA | Space Science | 2017 Oct 16
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by geckzilla » Tue Oct 17, 2017 2:56 am

Geez, bystander. Got your work cut out for you today.
Just call me "geck" because "zilla" is like a last name.

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ApJL Special Issue with Focus on GW170817

Post by bystander » Tue Oct 17, 2017 1:29 pm

Focus on the Electromagnetic Counterpart of the Neutron Star Binary Merger GW170817
Astrophysical Journal Letters | 848(2) | 2017 Oct 20

Multi-messenger Observations of a Binary Neutron Star Merger
B. P. Abbott et al. 2017 ApJL 848(2):L12 DOI: 10.3847/2041-8213/aa91c9
arXiv.org > astro-ph > arXiv:1710.05833 > 16 Oct 2017

Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
B. P. Abbott et al. 2017 ApJL 848(2):L13 DOI: 10.3847/2041-8213/aa920c
arXiv.org > astro-ph > arXiv:1710.05834 > 16 Oct 2017

An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A
A. Goldstein et al. 2017 ApJL 848(2):L14 DOI: 10.3847/2041-8213/aa8f41
arXiv.org > astro-ph > arXiv:1710.05446 > 16 Oct 2017

INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational-wave Event GW170817
V. Savchenko et al. 2017 ApJL 848(2):L15 DOI: 10.3847/2041-8213/aa8f94
arXiv.org > astro-ph > arXiv:1710.05449 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
I. Discovery of the Optical Counterpart Using the Dark Energy Camera

M. Soares-Santos et al. 2017 ApJL 848(2):L16 DOI: 10.3847/2041-8213/aa9059
arXiv.org > astro-ph > arXiv:1710.05459 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
II. UV, Optical, and Near-infrared Light Curves and Comparison to Kilonova Models

P. S. Cowperthwaite et al. 2017 ApJL 848(2):L17 DOI: 10.3847/2041-8213/aa8fc7
arXiv.org > astro-ph > arXiv:1710.05840 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
III. Optical and UV Spectra of a Blue Kilonova from Fast Polar Ejecta

M. Nicholl et al. 2017 ApJL 848(2):L18 DOI: 10.3847/2041-8213/aa9029
arXiv.org > astro-ph > arXiv:1710.05456 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
IV. Detection of Near-infrared Signatures of r-process Nucleosynthesis with Gemini-South

R. Chornock et al. 2017 ApJL 848(2):L19 DOI: 10.3847/2041-8213/aa905c
arXiv.org > astro-ph > arXiv:1710.05454 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
V. Rising X-Ray Emission from an Off-axis Jet

R. Margutti et al. 2017 ApJL 848(2):L20 DOI: 10.3847/2041-8213/aa9057
arXiv.org > astro-ph > arXiv:1710.05431 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
VI. Radio Constraints on a Relativistic Jet and Predictions for Late-time Emission from the Kilonova Ejecta

K. D. Alexander et al. 2017 ApJL 848(2):L21 DOI: 10.3847/2041-8213/aa905d
arXiv.org > astro-ph > arXiv:1710.05457 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
VII. Properties of the Host Galaxy and Constraints on the Merger Timescale

P. K. Blanchard et al. 2017 ApJL 848(2):L22 DOI: 10.3847/2041-8213/aa9055
arXiv.org > astro-ph > arXiv:1710.05458 > 16 Oct 2017

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817.
VIII. A Comparison to Cosmological Short-duration Gamma-Ray Bursts

W. Fong et al. 2017 ApJL 848(2):L23 DOI: 10.3847/2041-8213/aa9018
arXiv.org > astro-ph > arXiv:1710.05438 > 16 Oct 2017

The Discovery of the Electromagnetic Counterpart of GW170817: Kilonova AT 2017gfo/DLT17ck
Stefano Valenti et al. 2017 ApJL 848(2):L24 DOI: 10.3847/2041-8213/aa8edf
arXiv.org > astro-ph > arXiv:1710.05854 > 16 Oct 2017

A Deep Chandra X-Ray Study of Neutron Star Coalescence GW170817
Daryl Haggard et al. 2017 ApJL 848(2):L25 DOI: 10.3847/2041-8213/aa8ede
arXiv.org > astro-ph > arXiv:1710.05852 > 16 Oct 2017

The Unprecedented Properties of the First Electromagnetic Counterpart to a Gravitational-wave Source
M. R. Siebert et al. 2017 ApJL 848(2):L26 DOI: 10.3847/2041-8213/aa905e
arXiv.org > astro-ph > arXiv:1710.05440 > 16 Oct 2017

The Emergence of a Lanthanide-rich Kilonova Following the Merger of Two Neutron Stars
N. R. Tanvir et al. 2017 ApJL 848(2):L27 DOI: 10.3847/2041-8213/aa90b6
arXiv.org > astro-ph > arXiv:1710.05455 > 16 Oct 2017

The Environment of the Binary Neutron Star Merger GW170817
A. J. Levan et al. 2017 ApJL 848(2):L28 DOI: 10.3847/2041-8213/aa905f
arXiv.org > astro-ph > arXiv:1710.05444 > 16 Oct 2017

Observations of the First Electromagnetic Counterpart to a Gravitational-wave Source by the TOROS Collaboration
M. C. Díaz et al. 2017 ApJL 848(2):L29 DOI: 10.3847/2041-8213/aa9060
arXiv.org > astro-ph > arXiv:1710.05844 > 16 Oct 2017

The Old Host-galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational-wave Source
Y.-C. Pan et al. 2017 ApJL 848(2):L30 DOI: 10.3847/2041-8213/aa9116
arXiv.org > astro-ph > arXiv:1710.05439 > 16 Oct 2017

The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817
Jens Hjorth et al. 2017 ApJL 848(2):L31 DOI: 10.3847/2041-8213/aa9110
arXiv.org > astro-ph > arXiv:1710.05856 > 16 Oct 2017

The Rapid Reddening and Featureless Optical Spectra of the Optical Counterpart of GW170817, AT 2017gfo, during the First Four Days
Curtis McCully et al. 2017 ApJL 848(2):L32 DOI: 10.3847/2041-8213/aa9111
arXiv.org > astro-ph > arXiv:1710.05853 > 16 Oct 2017

Optical Follow-up of Gravitational-wave Events with Las Cumbres Observatory
Iair Arcavi et al. 2017 ApJL 848(2):L33 DOI: 10.3847/2041-8213/aa910f
arXiv.org > astro-ph > arXiv:1710.05842 > 16 Oct 2017

A Neutron Star Binary Merger Model for GW170817/GRB 170817A/SSS17a
A. Murguia-Berthier et al. 2017 ApJL 848(2):L34 DOI: 10.3847/2041-8213/aa91b3
arXiv.org > astro-ph > arXiv:1710.05453 > 16 Oct 2017
Last edited by bystander on Tue Oct 17, 2017 6:27 pm, edited 1 time in total.
Reason: added arXiv links
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by neufer » Tue Oct 17, 2017 2:31 pm

Click to play embedded YouTube video.
Art Neuendorffer

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GW170817 early relase papers at Nature, Science, and Physical Review Letters

Post by bystander » Tue Oct 17, 2017 4:22 pm

The X-ray counterpart to the gravitational-wave event GW170817
E. Troja et al. 2017 Nature DOI: 10.1038/nature24290
arXiv.org > astro-ph > arXiv:1710.05433 > 16 Oct 2017

Origin of the heavy elements in binary neutron-star mergers from a gravitational-wave event
Daniel Kasen et al. 2017 Nature DOI: 10.1038/nature24453
arXiv.org > astro-ph > arXiv:1710.05463 > 16 Oct 2017

Optical emission from a kilonova following a gravitational-wave-detected neutron-star merger
Iair Arcavi et al. 2017 Nature DOI: 10.1038/nature24291
arXiv.org > astro-ph > arXiv:1710.05843 > 16 Oct 2017

Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger
E. Pian et al. 2017 Nature DOI: 10.1038/nature24298
arXiv.org > astro-ph > arXiv:1710.05858 > 16 Oct 2017

A kilonova as the electromagnetic counterpart to a gravitational-wave source
S. J. Smartt et al. 2017 Nature DOI: 10.1038/nature24303
arXiv.org > astro-ph > arXiv:1710.05841 > 16 Oct 2017

A gravitational-wave standard siren measurement of the Hubble constant
B. P. Abbott et al. 2017 Nature DOI: 10.1038/nature24471
arXiv.org > astro-ph > arXiv:1710.05835 > 16 Oct 2017

The unpolarized macronova associated with the gravitational wave event GW 170817
S. Covino et al. 2017 Nature Astronomy DOI: 10.1038/s41550-017-0285-z
arXiv.org > astro-ph > arXiv:1710.05849 > 16 Oct 2017

Light curves of the neutron star merger GW170817/SSS17a: Implications for r-process nucleosynthesis
M. R. Drout et al. 2017 Science DOI: 10.1126/science.aaq0049
arXiv.org > astro-ph > arXiv:1710.05443 > 16 Oct 2017

Early spectra of the gravitational wave source GW170817: Evolution of a neutron star merger
B. J. Shappee et al. 2017 Science DOI: 10.1126/science.aaq0186
arXiv.org > astro-ph > arXiv:1710.05432 > 16 Oct 2017

Illuminating gravitational waves: A concordant picture of photons from a neutron star merger
M. M. Kasliwal et al. 2017 Science DOI: 10.1126/science.aap9455
arXiv.org > astro-ph > arXiv:1710.05436 > 16 Oct 2017

A radio counterpart to a neutron star merger
G. Hallinan et al. 2017 Science DOI: 10.1126/science.aap9855
arXiv.org > astro-ph > arXiv:1710.05435 > 16 Oct 2017

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova
P. A. Evans et al. 2017 Science DOI: 10.1126/science.aap9580
arXiv.org > astro-ph > arXiv:1710.05437 > 16 Oct 2017

Electromagnetic evidence that SSS17a is the result of a binary neutron star merger
C. D. Kilpatrick et al. 2017 Science DOI: 10.1126/science.aaq0073
arXiv.org > astro-ph > arXiv:1710.05434 > 16 Oct 2017

Swope Supernova Survey 2017a (SSS17a), the optical counterpart to a gravitational wave source
D. A. Coulter et al. 2017 Science DOI: 10.1126/science.aap9811
arXiv.org > astro-ph > arXiv:1710.05452 > 16 Oct 2017

GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
B. P. Abbott et al. (LIGO/Virgo) 2017 PRL DOI: 10.1103/PhysRevLett.119.161101
arXiv.org > astro-ph > arXiv:1710.05832 > 16 Oct 2017
Last edited by bystander on Tue Oct 17, 2017 7:02 pm, edited 1 time in total.
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by MargaritaMc » Tue Oct 17, 2017 7:30 pm

Yoicks, bystander - is there any science publication that HASN'T published on this?!
Remember, you saw it here ↓ first 8-)
http://asterisk.apod.com/viewtopic.php? ... 26#p274199
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by MargaritaMc » Tue Oct 17, 2017 7:40 pm

I'll add this article from Physics, the APS journal.
Viewpoint: Neutron Star Merger Seen and Heard
Maura McLaughlin, 

https://physics.aps.org/articles/v10/114
which I found to be a particularly succinct and informative summary
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by bystander » Tue Oct 17, 2017 7:59 pm

MargaritaMc wrote:I'll add this article from Physics, the APS journal.
Viewpoint: Neutron Star Merger Seen and Heard
Maura McLaughlin, 

https://physics.aps.org/articles/v10/114
which I found to be a particularly succinct and informative summary
The intro to the special issue at ApJL was good.
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by bystander » Tue Oct 17, 2017 8:13 pm

Know the quiet place within your heart and touch the rainbow of possibility; be
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by MargaritaMc » Tue Oct 17, 2017 8:15 pm

bystander wrote: The intro to the special issue at ApJL was good.
Yes, it was. I've made PDFs of both that one and the one by McLaughlin for ease of reference. (And I can make notes on them)

Actually, the New York Times piece was good too - very useful to pass on to friends who want to know what I am so very excited about!
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by BDanielMayfield » Thu Oct 19, 2017 3:28 pm

This was and is a great confirmation of expectations as to the site of heavy element production in the universe.

Recipe for making gold, uranium, etc.:
  • (1) Condense two close orbiting massive stars out of interstellar medium.
    (2) Allow cores of two stars to cook light elements up to iron.
    (3) Return excess gas and light elements back to interstellar medium via core collapse supernovae, producing binary neutron star pair.
    (4) Allow orbital decay to bring two neutron stars into contact, producing kilonova.
Alchemy is easy, if you have enough time and material.

Bruce
"Happy are the peaceable ... "

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by MargaritaMc » Thu Oct 19, 2017 4:06 pm

BDanielMayfield wrote:
Alchemy is easy, if you have enough time and material.

Bruce
That's very nice, Bruce. Thank you!
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by BDanielMayfield » Thu Oct 19, 2017 4:15 pm

MargaritaMc wrote:
BDanielMayfield wrote:
Alchemy is easy, if you have enough time and material.

Bruce
That's very nice, Bruce. Thank you!
Your very welcome. And all four steps are automatic, due to universal law.

Bruce
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by Ann » Fri Oct 20, 2017 12:15 am

MargaritaMc wrote:
BDanielMayfield wrote:
Alchemy is easy, if you have enough time and material.

Bruce
That's very nice, Bruce. Thank you!
I love it too.

Isaac Newton, Tycho Brahe, grumpy Swedish writer August Strindberg (world famous in Stockholm), and others, were missing a few ingredients.

Ann
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by Chris Peterson » Fri Oct 20, 2017 12:24 am

BDanielMayfield wrote:
MargaritaMc wrote:
BDanielMayfield wrote: Alchemy is easy, if you have enough time and material.
Bruce
That's very nice, Bruce. Thank you!
Your very welcome. And all four steps are automatic, due to universal law.
We call those "one pot meals".
Chris

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by MargaritaMc » Sun Oct 22, 2017 5:00 pm

The Sky & Telescope article by Govert Schilling (who as always is an excellent read)
http://www.skyandtelescope.com/astronom ... ron-stars/
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS

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HITS: Neutron Stars on the Brink of Collapse (GW170817)

Post by bystander » Tue Dec 05, 2017 3:44 pm

Neutron Stars on the Brink of Collapse
Heidelberg Institute for Theoretical Studies | 2017 Dec 04
[img3="The upper and lower series of pictures each show a simulation of a neutron star merger. In the scenario shown in the upper panels the star collapses after the merger and forms a black hole, whereas the scenario displayed in the lower row leads to an at least temporarily stable star. (Image: Andreas Bauswein, HITS)"]https://www.h-its.org/wp-content/upload ... se_pic.jpg[/img3][hr][/hr]
Neutron stars are the densest objects in the Universe; however, their exact characteristics remain unknown. Using simulations based on recent observations, a team of scientists including HITS researcher Dr. Andreas Bauswein has managed to narrow down the size of these stars.

When a very massive star dies, its core contracts. In a supernova explosion, the star’s outer layers are expelled, leaving behind an ultra-compact neutron star. For the first time, the LIGO and Virgo Observatories have recently been able to observe the merger of two neutron stars and measure the mass of the merging stars. Together, the neutron stars had a mass of 2.74 solar masses. Based on these observational data, an international team of scientists from Germany, Greece, and Japan including HITS astrophysicist Dr. Andreas Bauswein has managed to narrow down the size of neutron stars with the aid of computer simulations. The calculations suggest that the neutron star radius must be at least 10.7 km. The international research team’s results have been published in “Astrophysical Journal Letters.”

In neutron star collisions, two neutron stars orbit around each other, eventually merging to form a star with approximately twice the mass of the individual stars. In this cosmic event, gravitational waves – oscillations of spacetime – whose signal characteristics are related to the mass of the stars, are emitted. This event resembles what happens when a stone is thrown into water and waves form on the water’s surface. The heavier the stone, the higher the waves. ...

Neutron-Star Radius Constraints from GW170817 and Future Detections - Andreas Bauswein et al
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by neufer » Sun Dec 17, 2017 10:44 pm

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Art Neuendorffer

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LBNL: Star Mergers: A New Test of Gravity, Dark Energy Theories

Post by bystander » Tue Dec 19, 2017 4:56 pm

Star Mergers: A New Test of Gravity, Dark Energy Theories
Lawrence Berkeley National Laboratories | 2017 Dec 18

Observations of neutron star collision challenge some existing theories
[c][youtube]https://www.youtube.com/watch?v=UIBaq5v7oL4[/youtube]Last Dance of Neutron Star Pair
Credit: W. Kastaun/T. Kawamura/B. Giacomazzo/R. Ciolfi/A. Endrizzi
[/c]
When scientists recorded a rippling in space-time, followed within two seconds by an associated burst of light observed by dozens of telescopes around the globe, they had witnessed, for the first time, the explosive collision and merger of two neutron stars.

The intense cosmological event observed on Aug. 17 also had other reverberations here on Earth: It ruled out a class of dark energy theories that modify gravity, and challenged a large class of theories.

Dark energy, which is driving the accelerating expansion of the universe, is one of the biggest mysteries in physics. It makes up about 68 percent of the total mass and energy of the universe and functions as a sort of antigravity, but we don’t yet have a good explanation for it. Simply put, dark energy acts to push matter away from each other, while gravity acts to pull matter together.

The neutron star merger created gravitational waves – a squiggly distortion in the fabric of space and time, like a tossed stone sending ripples across a pond – that traveled about 130 million light-years through space, and arrived at Earth at almost the same instant as the high-energy light that jetted out from this merger.

The gravity waves signature was detected by a network of Earth-based detectors called LIGO and Virgo, and the first intense burst of light was observed by the Fermi Gamma-ray Space Telescope.

That nearly simultaneous arrival time is a very important test for theories about dark energy and gravity. ...

Dark Energy after GW170817: Dead Ends and the Road Ahead - Jose María Ezquiaga, Miguel Zumalacárregui
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by BDanielMayfield » Wed Dec 20, 2017 5:22 am

That article caught my attention bystander. Had to read more, wondering what this event might have to say re MOND theories. Note this excerpt:
A 100-year-old “cosmological constant” theory introduced by Albert Einstein in relation to his work on general relativity and some other theories derived from this model remain as viable contenders because they propose that dark energy is a constant in both space and time: Gravitational waves and light waves are affected in the same way by dark energy, and thus travel at the same rate through space.

“The favorite explanation is this cosmological constant,” he said. “That’s as simple as it’s going to get.”

There are some complicated and exotic theories that also hold up to the test presented by the star-merger measurements. Massive gravity, for example – a theory of gravity that assigns a mass to a hypothetical elementary particle called a graviton – still holds a sliver of possibility if the graviton has a very slight mass.

Some other theories, though, which held that the arrival of gravitational waves would be separated in time from the arriving light signature of the star merger by far longer periods – stretching up to millions of years – don’t explain what was seen, and must be modified or scrapped.

The study notes that a class of theories known as scalar-tensor theories is particularly challenged by the neutron-star merger observations, including Einstein-Aether, MOND-like (relating to modified Newtonian dynamics), Galileon, and Horndeski theories, to name a few.
So there goes MOND down the drain, and Einstein's "biggest mistake" gets even bigger.

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by Ann » Wed Dec 20, 2017 5:44 am

BDanielMayfield wrote:That article caught my attention bystander. Had to read more, wondering what this event might have to say re MOND theories. Note this excerpt:
A 100-year-old “cosmological constant” theory introduced by Albert Einstein in relation to his work on general relativity and some other theories derived from this model remain as viable contenders because they propose that dark energy is a constant in both space and time: Gravitational waves and light waves are affected in the same way by dark energy, and thus travel at the same rate through space.

“The favorite explanation is this cosmological constant,” he said. “That’s as simple as it’s going to get.”

There are some complicated and exotic theories that also hold up to the test presented by the star-merger measurements. Massive gravity, for example – a theory of gravity that assigns a mass to a hypothetical elementary particle called a graviton – still holds a sliver of possibility if the graviton has a very slight mass.

Some other theories, though, which held that the arrival of gravitational waves would be separated in time from the arriving light signature of the star merger by far longer periods – stretching up to millions of years – don’t explain what was seen, and must be modified or scrapped.

The study notes that a class of theories known as scalar-tensor theories is particularly challenged by the neutron-star merger observations, including Einstein-Aether, MOND-like (relating to modified Newtonian dynamics), Galileon, and Horndeski theories, to name a few.
So there goes MOND down the drain, and Einstein's "biggest mistake" gets even bigger.

Bruce
Perhaps not. Einstein's "biggest mistake", as he saw it, was introducing the cosmological constant "to keep the cosmos constant" and prevent it from either expanding or contracting. But what is said in the article above is that a cosmological constant may be the best explanation for the dark energy in the Universe.

So Einstein may have been absolutely right in seeing the need of introducing the cosmological constant. He was just dead wrong about what the cosmological constant would do.

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by neufer » Wed Dec 20, 2017 1:59 pm

Ann wrote:
BDanielMayfield wrote:
So there goes MOND down the drain, and Einstein's "biggest mistake" gets even bigger.
Perhaps not. Einstein's "biggest mistake", as he saw it, was introducing the cosmological constant "to keep the cosmos constant" and prevent it from either expanding or contracting. But what is said in the article above is that a cosmological constant may be the best explanation for the dark energy in the Universe. So Einstein may have been absolutely right in seeing the need of introducing the cosmological constant. He was just dead wrong about what the cosmological constant would do.
Einstein produced a general equation that couldn't rule out the existence of a cosmological constant.

Einstein was unhappy in not knowing a prior the value of that constant.

But he was only wrong it was in believing that that equation had a stable solution ... which it doesn't.
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Caltech: Update on Neutron Star Smash-up: Jet Hits a Roadblock

Post by bystander » Wed Dec 20, 2017 7:09 pm

Update on Neutron Star Smash-up: Jet Hits a Roadblock
California Institute of Technology | 2017 Dec 20

Radio observations are illuminating what happened during recent gravitational-wave event
[c][attachment=0]Hallinan_Kasliwal-NS-NS-Merger_Comparison-CocoonModel.jpg[/attachment][/c][hr][/hr]
Millions of years ago, a pair of extremely dense stars, called neutron stars, collided in a violent smash-up that shook space and time. On August 17, 2017, both gravitational waves—ripples in space and time—and light waves emitted during that neutron star merger finally reached Earth. The gravitational waves came first and were detected by the twin detectors of the National Science Foundation (NSF)-funded Laser Interferometry Gravitational-wave Observatory (LIGO), aided by the European Virgo observatory. The light waves were observed seconds, days, and months later by dozens of telescopes on the ground and in space.

Now, scientists from Caltech and several other institutions are reporting that light with radio wavelengths continues to brighten more than 100 days after the August 17 event. These radio observations indicate that a jet, launched from the two neutron stars as they collided, is slamming into surrounding material and creating a slower-moving, billowy cocoon. ...

On August 17, NASA's Fermi Gamma-ray Space Telescope and the European INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) missions detected gamma rays just seconds after the neutron stars merged. The gamma rays were much weaker than what is expected for sGRBS, so the researchers reasoned that a fast and narrowly focused jet was produced but must have been pointed slightly askew from the direction of Earth, or off-axis.

The radio emission—originally detected 16 days after the August 17 event and still measurable and increasing in strength as of December 2—tells a different story. If the jet had been fast and beam-like, the radio light would have weakened with time as the jet lost energy. The fact that the brightness of the radio light is increasing instead suggests the presence of a cocoon that is choking the jet. The reason for this is complex, but it has to do with the fact that the slower-moving, wider-angle material of the cocoon gives off more radio light than the faster-moving, sharply focused jet material. ...

Radio Observations Point to Likely Explanation for Neutron-Star Merger Phenomena
National Radio Astronomy Observatory | VLA | 2017 Dec 20

Neutron-star merger creates new mysteries
ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO) | 2017 Dec 21

A mildly relativistic wide-angle outflow in the neutron-star merger event GW170817 - K. P. Mooley et al
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Re: First Light from a Gravitational Wave Event (GW170817)

Post by BDanielMayfield » Thu Dec 21, 2017 12:49 pm

neufer wrote:
Ann wrote:
BDanielMayfield wrote:
So there goes MOND down the drain, and Einstein's "biggest mistake" gets even bigger.
Perhaps not. Einstein's "biggest mistake", as he saw it, was introducing the cosmological constant "to keep the cosmos constant" and prevent it from either expanding or contracting. But what is said in the article above is that a cosmological constant may be the best explanation for the dark energy in the Universe. So Einstein may have been absolutely right in seeing the need of introducing the cosmological constant. He was just dead wrong about what the cosmological constant would do.
Einstein produced a general equation that couldn't rule out the existence of a cosmological constant.

Einstein was unhappy in not knowing a prior the value of that constant.

But he was only wrong it was in believing that that equation had a stable solution ... which it doesn't.
Clarification: I was just using "Einstein's biggest mistake" as another way of saying cosmological constant. He himself called it that, but ironically, it now seems very likely that he wasn't wrong at all, and thus his real mistake was thinking he was wrong. It is this irony that gets bigger as the need for his cosmological constant grows.

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Re: First Light from a Gravitational Wave Event (GW170817)

Post by neufer » Thu Dec 21, 2017 3:56 pm

BDanielMayfield wrote:
neufer wrote:
Ann wrote:
Einstein's "biggest mistake", as he saw it, was introducing the cosmological constant "to keep the cosmos constant" and prevent it from either expanding or contracting. But what is said in the article above is that a cosmological constant may be the best explanation for the dark energy in the Universe. So Einstein may have been absolutely right in seeing the need of introducing the cosmological constant. He was just dead wrong about what the cosmological constant would do.
Einstein produced a general equation that couldn't rule out the existence of a cosmological constant.

Einstein was unhappy in not knowing a prior the value of that constant.

But he was only wrong it was in believing that that equation had a stable solution ... which it doesn't.
Clarification: I was just using "Einstein's biggest mistake" as another way of saying cosmological constant.

He himself called it that, but ironically, it now seems very likely that he wasn't wrong at all,
and thus his real mistake was thinking he was wrong.
https://qz.com/113811/for-almost-a-century-people-have-been-misquoting-einsteins-biggest-mistake/ wrote:

Einstein may never have uttered the phrase “biggest blunder.”
by Rebecca J. Rosen, The Atlantic_, August 09, 2013

<<Astrophysicist and author Mario Livio can find no documentation that puts those words [i.e., “biggest blunder”] into Einstein’s mouth (or, for that matter, his pen). Instead, all references eventually lead back to one man, physicist George Gamow, who reported Einstein’s use of the phrase in two sources: his posthumously published autobiography My World Line (1970) and a Scientific American article from September 1956. :arrow:

This, for reasons Livio recounts in detail in his new book Brilliant Blunders, is some seriously thin sourcing. For one, Gamow, brilliant physicist though he might have been, had a bit of a reputation for, shall we say, antics. Once, for example, Gamow had teamed up with a student of his named Ralph Alpher to write a paper. “He then realized,” Livio told me, “that if he were to add as a co-author another known astrophysicist, whose name was Hans Bethe, then the three names would be Alpher Bethe Gamow, like alpha beta gamma, even though Hans Bethe hadnothing to do with that paper.” (His first wife, Livio writes, once remarked, “In more than twenty years together, Geo has never been happier than when perpetuating a practical joke.”)

Livio looked at almost every single paper that Einstein ever wrote, including making a trip to the Einstein archive in Jerusalem to look at the collection personally. “And nowhere did I ever find the phrase ‘biggest blunder’, ” Livio told me. “I didn’t find it—anywhere.”

So he turned his attention to the correspondence between Einstein and Gamow, and it is at this point that Gamow’s story begins to look even worse. “When might Einstein have used this expression with Gamow?” Livio writes in the book. As Gamow tells it in his autobiography, he and Einstein were quite close, with Gamow visiting the aging scientist every other Friday as the liaison between the Navy and Einstein during World War II. “He describes what good friends they were, how Einstein would greet him in one of his soft sweaters, and so on,” Livio explains.

“Well, guess what,” he continues. “I discovered a small article published in some obscure journal of the Navy by somebody named Stephen Brunauer,” a scientist who had recruited both Einstein and Gamow to the Navy. In that article, Brunauer wrote, “Gamow, in later years, gave the impression that he was the Navy’s liaison man with Einstein, that he visited every two weeks, and the professor ‘listened’ but made no contribution—all false [emphasis added]. The greatest frequency of visits was mine, and that was about every two months.” Clearly, Livio says, Gamow exaggerated his relationship with the famous physicist. The correspondence between Einstein and Gamow seems to confirm this. The letters are quite formal, not those of the sort that would pass between intimate friends. Einstein was polite but not particularly effusive. “So wait a second,” Livio says doubtfully, “Einstein never used this phrase with any more intimate colleagues, but he used it with Gamow?”

Moreover, this is not to say that Einstein was at ease with the cosmological constant. “I’m not saying he didn’t regret it,” Livio says. “He definitely regretted it. He wrote about that to a number of friends. He thought it was ugly.” But to say it was his “biggest blunder” implies a level of regret that it seems Einstein did not feel. By contrast, when he did write about the error (which, it should be noted, in more recent years, has turned out to be less clearly an error than Einstein thought, but that’s a whole other story), he did so with a dispassionate tone that conveys comfort with the notion that science would overturn some of his work. In a 1932 paper with Willem de Sitter, Einstein wrote, “Historically the term containing the ‘cosmological constant’ Λ was introduced into the field equations in order to enable us to account theoretically for the existence of a finite mean density in a static universe. It now appears that in the dynamical case this end can be reached without the introduction of Λ.” And that was that.

There was, however, one regret that stood out for Einstein, and it had nothing to do with the elegance of his calculations. After a visit with the scientist at Princeton on November 16, 1954, Linus Pauling wrote in his diary: “He said that he had made one great mistake—when he signed the letter to Pres. Roosevelt recommending that atom bombs be made; but that there was some justification—the danger that the Germans would make them.”>>
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