LIGO Spots Another Gravitational Wave Soon After Powering Back On

New submitter nichogenius writes: The latest observation run of LIGO and VIRGO only started April 1st, but has already observed another black hole merger. The LIGO detectors have been offline since the 25th of August, 2017 for a series of upgrades. The latest observational run is the first run where gravitational wave events are being publicly announced as they happen rather than being announced weeks or months later. Few details of the merger are available at this time, but there is some information available on LIGO's twitter and raw details can be obtained from LIGO's event database page.

Gravitational detection events are being publicly broadcast using NASA's VOEvent system. If you know a bit of python, you can setup your own VOEvent client using the pygcn module with example code available in this tutorial.

Run! Run to the hills!

[Hognoxious]

It won't do any good, will it?

new scientist article

[e**(i pi)-1]

it is nice to see that machine back on and working. I would have liked a bit more background, what actually has changed during the upgrade. It seems that this contained only in a ``premium article" in the new scientist. Fortunately there are other sources where on can look things up: 40 percent more sensitive machine leading to twice the volume of space to be observable. Some main mirrors were replaced, the laser power increased and a technique called ``squeezing" introduced which counteracts the now stronger distortion of the beam. Also new is that detections of events are publicly announced as soon as they are available. Here is the source: https://news.stanford.edu/2019... [stanford.edu]

Re:new scientist article

[epine]

You missed improvements in event localization to enable traditional astronomy to zoom in on neutron star mergers with an electromagnetic signature. This includes a wide-aperture radio facility (IIRC) and an improved algorithm to search the probable area. Plus, if they have all three facilities in good working order, they get a smaller statistical banana in space to start with (perhaps to improve again once the Japanese facility begins to participate, which I think is slated for later in the year).

Thanks for that link.

[Anonymous Coward]

Really. That is what I read Slashdot comments for. Much appreciated.

Re:new scientist article

[Sique]

I like this quote in the aforementioned link:

One of the things that makes that interesting is that when the moon goes overhead, the ground goes up and down by about plus or minus six inches. When this bulge travels past the LIGO sites, the arms of the detectors get stretched. The isolation tables have to compensate for that motion so that the distances between the optics doesn’t change.

Re:

[omfglearntoplay]

Yeah, the amount the moon affects the dirt under our feet is really weird. My kid was very surprised when it was brought up in his grade school science class.

https://en.wikipedia.org/wiki/... [wikipedia.org]

Re:

[tehcyder]

when the moon goes overhead, the ground goes up and down by about plus or minus six inches

Yeah sure, if that was true then the moon would make the oceans rise and fall on a regular daily basis, rather than being at sea level all the time.

What sort of idiots do these so-called scientists take us for?

Re:

[BranMan]

Um... You DO realize that not everywhere has tides, right?

Re:

[skaralic]

Some main mirrors were replaced, the laser power increased and a technique called ``squeezing" introduced which counteracts the now stronger distortion of the beam.

What, no Blockchain and AI?

Re:

[jfdavis668]

Swing and a miss...

Re: first post!

[koki22]

The isolation tables have to compensate for that motion so that the distances between the optics doesnâ(TM)t change https://audacity.onl/ [audacity.onl] https://findmyiphone.onl/ [findmyiphone.onl] https://origin.onl/ [origin.onl]

python?

[Anonymous Coward]

Python? Ew. Come on NASA, you can do better.

Overenthousiastic scientist?

[trenien]

The article talks about detecting 'massive' black holes, and goes on to add them to be around 30x the mass of the Sun.

Why call upon black holes, then? As far as I remember, you can have stars significantly more massive than that before the collapse into a black hole becomes the only explanation to describe what was observed.

With only that presented as evidence, it sounds like someone was a bit overeager to justify the LIGO's budget with claims of an extraordinary observation.

Re:

[trenien]

Damn, too quick on the draw....

overenthUsiastic

Re:

[Sique]

Because stars tend not to merge with each other, and thus they don't send out strong gravitational waves. As long as they radiate strongly, they would rather repulse each other than merge.

Re:Overenthousiastic scientist?

[trenien]

And yet, no physics law prohibits it

https://en.wikipedia.org/wiki/... [wikipedia.org]

As a matter of fact, the very same LIGO let us see two neutron stars doing that exactly back in 2017.

On the other hand, as far as I'm aware, there are no conclusive observation of black holes, which makes for a much more spectacular headline.

Re:Overenthousiastic scientist?

[Sique]

Neutron stars don't have a large radiation pressure. They are inactive stars. Yes, they accelerate stuff from their accredition disc, and thus they send out huge amounts of particles and synchrotron radiation, but only on their poles. But around their equator, they don't have any radiation pressure at all.

Re:

[necro81]

The physics of a collision of 30x stellar mass stars would be very different than for black holes, if only because stars have a (comparatively) large spatial extent, while the black holes are much more compact and, as a result, can get their masses much closer together before they merge. Compact masses getting close together creates 1) very strong gravitational disturbances and 2) very fast orbital speeds. Large stars can't get their masses close enough, and could not orbit each other fast enough, to be d

Re:

[dargaud]

The amount of gravitational waves generated by 2 stars colliding is many orders of magnitude less than 2 black holes colliding: In the black hole merger recently observed by LIGO, about 5% of energy was radiated in the form of gravitational waves. In other words, several suns went out in pure energy. That's a LOT of energy, hence why we can detect black hole collisions, but no way we can detect star collisions.

Also orbiting black holes loses energy pretty fast due to (again) radiating it as gravitational

Re:

[dargaud]

On the other hand, as far as I'm aware, there are no conclusive observation of black holes, which makes for a much more spectacular headline.

And by the way, as of an hour ago, that's not true anymore [slashdot.org]

Re:

[ivano]

BHs are small compared to their mass-equivalent star size. Because of this they can orbit pretty close to each other before actually merging. This means they can go a percentage of the speed of light when orbiting each other and so create bigger gravitational waves. There is a difference between gravitational waves and gravity.

Re:

[Sique]

And then there is another reason: You want events that send out gravitational waves with a frequency between 100 Hz and 3000 Hz, because that's where LIGO is sensitive. Thus you are confined in the mass of the objects whose gravitational events you can monitor. For other frequencies you either need much larger instruments (e.g. of the length of the Earth's diameter or even larger), or much higher resolutions for the measurements.

Re:

[MightyMartian]

It's the most sensitive instrument ever developed. The technical leap that made LIGO possible is likely to have a vast number of applications going forward.

Re:

[Shotgun]

Billions?

Dude, its a friggin' concrete pipe with a laser bouncing between a few mirrors. This is some of the cheapest science the modern era has to offer, and for the effort we get to push the envelope of how sensitive we can make instruments.

and before to blow that off, consider that the latest iteration of the industrial revolution that has driven quality in consumer level products has been driven by accurate measurements. The typical car of the 70's came off the line with the equivalent of 50,000 miles

Re:

[jfdavis668]

Stretching spacetime does not necessary imply a change to the time portion. They only impact the space. In normal situations, stretching something would imply accelerating each end away from then toward the other. By what I understand, gravitational waves do not accelerate matter. They stretch space. The objects do not move in relation to space, so there is no time dialation involved.