"we should not expect the first NS-NS GWs to be accompanied by a GRB"
October 15, 2017 10:18 AM   Subscribe

20 months after announcing the first gravitational wave detection, and two weeks after winning the Nobel Prize, the LIGO-Virgo collaboration returns to the National Press Club on Monday morning at 10 am to reveal "groundbreaking observations" relating to "an astronomical phenomenon that has never been witnessed before." (live stream links: 1 2)

Rumors swirled in late August of a new gravitational wave (GW) detection by the LIGO-VIRGO collaboration. These rumors were amplified and given credibility by reports of a coincident short gamma ray burst (GRB) detection by the Fermi space telescope, and emergency extended requisitions of the Chandra X-ray Telescope, the Hubble Space Telescope (live-tweeted, helpfully), and the Gemini South optical/infrared telescope... all pointed at the modest elliptical galaxy NGC4993, 130 Mly away.

Although LIGO has not confirmed a detection, these hints point to the GW detection of a binary neutron star merger, together with confirmation and precise localization by conventional telescopes. Such a merger is predicted to produce a short, beamed, GRB followed by an isotropically visible kilonova (see Introduction for the entire GW-GRB-kilonova connection, and the origin of this post title).

The confirmation of a GW detection by telescopic observations would complete the integration of gravitational waves into astronomy; the press event on Monday will feature scientists and representatives of 70 observatories from around the world.
posted by pjenks (38 comments total) 36 users marked this as a favorite
 
disclaimer: I'm not a member of LIGO or any associated astronomical projects, and I have no inside information... I'm just a curious and excited onlooker!
posted by pjenks at 10:21 AM on October 15, 2017 [2 favorites]


Huh. Looking at the 'kilonova' link, today's Astronomy Picture of the Day makes more sense...
tl;dr: GOLD! There's too much gold in the universe to be explained by the big bang or conventional supernovae, so a neutron-rich encounter (such as between neutron stars) is probably responsible for the amount of gold and other neutron-heavy elements that we see.
posted by sexyrobot at 10:29 AM on October 15, 2017 [4 favorites]


Looking up kilonova led me to this nicely put together periodic table showing the cosmic origin of each element. I had forgotten, if I ever knew, that there was as light as element as technetium that has no stable isotopes.
posted by tavella at 11:06 AM on October 15, 2017 [10 favorites]


Though this article may have a more accurate version.
posted by tavella at 11:18 AM on October 15, 2017 [5 favorites]


I definitely misread that as "LEGO-Virgo collaboration" at first. That is all.
posted by limeonaire at 11:41 AM on October 15, 2017 [4 favorites]


"Let me tell ye suthin’—some day yew folks’ll hear a child o’ Lavinny’s a-callin’ its father’s name at a LIGO-Virgo press conference!"
posted by GenjiandProust at 11:43 AM on October 15, 2017 [8 favorites]


I definitely misread that as "LEGO-Virgo collaboration" at first.

Better that than a VIGO-Janosz collaboration.
posted by Talez at 12:01 PM on October 15, 2017 [8 favorites]


Though this article may have a more accurate version.

Woah that’s cool. Now I have to go look up what cosmos ray fission is. I was surprised, given the curve of binding energy, that there isn’t some sudden sharp transition on that chart with iron. Elements either side of iron have pretty similar sources.
posted by Jimbob at 12:54 PM on October 15, 2017


"More inside" does not clarify what Nova Scotia-Nova Scotia has to do with GWs or GRBs (though I was glad to learn that the post had nothing to do with another visit by the former US president GW Bush to the province).
posted by eviemath at 1:21 PM on October 15, 2017 [2 favorites]


I feel dissatisfied. I require reports on astronomical events to tell me three things, preferably in this order:
1) Are we all going to die?
2) Is it aliens?
3) Are there cool photos?

These cutting-edge press releases are all very well, but they don't really fit my needs. I think I'll have to wait for the story to be covered by The Daily Mail.
posted by Joe in Australia at 2:04 PM on October 15, 2017 [8 favorites]


1) Yes.
2) No.
3) Maybe?
posted by pjenks at 2:20 PM on October 15, 2017 [2 favorites]


So this is how we live now - teasers for science press conferences?
posted by thelonius at 3:44 PM on October 15, 2017 [6 favorites]


Jimbob: Now I have to go look up what cosmos ray fission is.

I had to look it up too. The other surprise was that supernova/classical nova contribution dies out entirely at zirconium, and after the stuff that isn't from neutron stars colliding is slow-cooked in low-mass red giants. And that they can produce all the way up to lead and a tiny bit of bismuth.
posted by tavella at 4:40 PM on October 15, 2017 [1 favorite]


MetaFilter: all the way up to lead and a tiny bit of bismuth.
posted by GenjiandProust at 4:52 PM on October 15, 2017 [1 favorite]


>> I require reports on astronomical events to tell me three things, preferably in this order:
>> 1) Are we all going to die?
>> 2) Is it aliens?
>> 3) Are there cool photos?

> 1) Yes.
> 2) No.
> 3) Maybe?


1. Eventually, I guess, unless we all get raptured in the Singularity. Not because of this event!
2. No.
3. Oh, yes.

(I am not directly involved in any of the press hoopla tomorrow, but I am bound by the embargo. As are maybe a thousand of my colleagues, I guess...)
posted by RedOrGreen at 6:42 PM on October 15, 2017 [2 favorites]


> So this is how we live now - teasers for science press conferences?

Well you could join us in the Trump thread and be depressed instead...

I hear that Kilonova.org goes live at 10 AM US/Eastern, and will have all the answers.
posted by RedOrGreen at 6:45 PM on October 15, 2017 [1 favorite]


The WhoIs shows it's registered to Edo Berger. But I guess you already knew that, RedOrGreen. He's probably the keeper of the cool photos too?
posted by pjenks at 7:02 PM on October 15, 2017 [1 favorite]


The color for Pm, Tc, Fr, Ra, Np, and others is not covered by the legend. What does puke-green represent?
posted by I-Write-Essays at 12:01 AM on October 16, 2017


Are there cool photos?

It would be amazing if they just release a 1 pixel animated gif of the LIGO photodetector output.
posted by ryanrs at 2:55 AM on October 16, 2017 [1 favorite]


The color for Pm, Tc, Fr, Ra, Np, and others is not covered by the legend. What does puke-green represent?

Those elements have no long lived stable isotopes IIRC, but leaving gaps in the table would look a bit weird. (Longest Neptunium isotope half life is on the order of 2 million years for instance.)
posted by pharm at 4:47 AM on October 16, 2017


I hope you guys are watching the live press conference. There's a LOT of stuff!
posted by RedOrGreen at 7:21 AM on October 16, 2017 [1 favorite]


Here's the direct link to the LIGO announcement and press conference taking place right now.

It is extremely interesting and totally accessible to non-experts. You should all tune in!
posted by Westringia F. at 7:29 AM on October 16, 2017


(Also: there's a bunch amazing women astrophysicists speaking! Vicky Kalogera, Marica Branchesi, Julie McEnery.... I don't work in this field any more, but I happen to know some of them, and they're PHENOMENAL. So excited to see them get the press they richly deserve!!!

This is particularly moving because pulsars -- the rotating neutron stars observed here -- were first discovered by a woman, Jocelyn Bell Burnell... but her advisor was awarded the Nobel prize for it, not her.)

posted by Westringia F. at 7:43 AM on October 16, 2017 [2 favorites]


I am so very glad the embargo is over. Especially considering how leaky the process was. To quote Matthew Buckley on Twitter,
Congratulations to LIGO for experimental evidence that scientists can’t keep secrets for shit.
posted by miguelcervantes at 7:46 AM on October 16, 2017


Holy cow, this provides an entirely new way to calibrate the measurement of the Hubble expansion! That hadn't occurred to me. They have an independent distance measurement from the gravitational wave intensity and a host galaxy identified from the optical signals. Awesome!
posted by heatherlogan at 7:56 AM on October 16, 2017 [4 favorites]


Holy cow, this provides an entirely new way to calibrate the measurement of the Hubble expansion!

That was my first thought and I am so verklempt right now. My father was the Telescope Scientist who designed the mirrors for the Chandra X-ray Observatory. He died Christmas Day, 2002 which meant that he lived long enough to know that it was a big success (it launched in 1999) but not long enough to see its many contributions or complete his own scheduled observations, which concerned the Hubble expansion (others used his time and published a few years later). Many of the people involved in LIGO and today’s presentation were his friends, and he would have been delighted for them, for his own work and for science.
posted by carmicha at 8:05 AM on October 16, 2017 [20 favorites]


I haven't seen an explanation for the 2 second lag yet. Can anyone point me to it?
posted by Shutter at 8:21 AM on October 16, 2017


Yeah, here's the Nature paper: A gravitational-wave standard siren measurement of the Hubble constant

GW170817 can be used as a standard siren, combining the distance inferred purely from the gravitational-wave signal with the recession velocity arising from the electromagnetic data to determine the Hubble constant. This quantity, representing the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Our measurements do not require any form of cosmic ‘distance ladder’; the gravitational-wave analysis directly estimates the luminosity distance out to cosmological scales. Here we report H0 =  70.0+12.0-8.0 kilometres per second per megaparsec, which is consistent with existing measurements, while being completely independent of them.
The 2 second lag is just the time needed for the breakout of the explosion - gravitational waves are generated by the merger and travel out at the speed of light, but the explosion has to push aside matter in order to let the light emerge.

(But even ignoring that effect, light and gravitational waves arrived less than 2 seconds apart after traveling for 130 million years - that's agreement to one part in 2 million billion or so. That's an amazing result on its own terms.)
posted by RedOrGreen at 8:27 AM on October 16, 2017 [4 favorites]


I'm curious -- how much interference is there with gravitational waves across cosmic distances? I.e., what happens when a gravitational wave passes across a black hole, is it lost or distorted? Googling for this is just getting me info about black holes causing gravitational waves.
posted by tavella at 8:54 AM on October 16, 2017 [1 favorite]


> How much interference is there with gravitational waves across cosmic distances?

I haven't thought about this before, but the effect is almost certainly negligible. Compact objects are (by definition) compact, and their cross-section is negligible on the sky. With large masses like galaxy clusters, I expect there would be gravitational lensing of gravitational waves, just like gravitational lensing of light - why not? - but that's completely undetectable at current resolution and sensitivity, I think...
posted by RedOrGreen at 8:59 AM on October 16, 2017


My father was the Telescope Scientist who designed the mirrors for the Chandra X-ray Observatory. 

Holy sh!t, no way! That mirror design is so brilliant that I find myself telling totally random strangers about them all. the. time.
Totally cool that your dad designed them. (My father figured out how to do rhinoplasties without having to pack the nose with bandages afterwards so healing time is greatly reduced. (The trick is in the cartilage splicing and the liberal use of cocaine during surgery-on the patient's septum, not by the doctor ;p))
posted by sexyrobot at 9:06 AM on October 16, 2017 [5 favorites]


Here's the NYTimes article:
LIGO Detects Fierce Collision of Neutron Stars for the First Time
whose headline sort of undersells the magnitude of this enormous collaborative effort.
posted by pjenks at 9:12 AM on October 16, 2017 [1 favorite]


“Photo” to me refers to the electromagnetic spectrum specifically. So yeah, there’s photos (the electromagnetic signal) but they’re correlated with something else— maybe “gravotos”? (Is there a name for a gravitational wave snapshot yet?) And that’s what super nifty here: we have photos AND gravotos.

I am a theorist, and mostly the wrong kind to be useful here, but man LIGO is just so nifty.
posted by nat at 10:53 AM on October 16, 2017 [1 favorite]


Here we report H0 =  70.0+12.0-8.0 kilometres per second per megaparsec, which is consistent with existing measurements, while being completely independent of them.

Since I remain Verklempt and am ambling down memory lane right now, this pleases me. The Chandra effort to determine the Hubble constant associated with the experiments my father planned came up with 77 kilometers per second per megaparsec.
posted by carmicha at 11:29 AM on October 16, 2017


There's a Reddit AMA with the Swope Discovery Team that did some of the optical observations.
posted by Nelson at 11:12 AM on October 17, 2017


To me, an interesting sidelight to this is that if you play the tape in reverse (generally permissible under the laws of physics however improbable the outcome) you get a recipe for destroying a black hole.

All you have to do is arrange a convergence of powerful gravitational waves, relativistic jets and gamma ray bursts, and a collapsing shell of heavy elements onto a poor, unsuspecting tiny black hole, and it splits into two neutron stars which then spin away from each other and go their separate ways -- and I have a feeling you could dispense with everything except the converging gravitational waves.
posted by jamjam at 1:26 PM on October 17, 2017 [1 favorite]


if you play the tape in reverse . . . you get a recipe for destroying a black hole

I'm no expert, but I think it's safe to say that when black holes are involved, the reversibility of physics is not a straightforward topic.
posted by mubba at 8:09 AM on October 18, 2017 [2 favorites]


Well, it would be the universe's greatest physics experiment. Generate gravitational waves so strong and so long amplitude that they expand space enough to reduce the black hole's density so much and for a long enough period that it is no longer dense enough to be a black hole and see what happens.

Just need some gravitational waves as powerful as those generated in a black hole merger, but with a wavelength more like a light year.
posted by wierdo at 3:10 PM on October 18, 2017


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