Results of the deepest all-sky survey for continuous gravitational waves on LIGO S6 data

The analysis of the results from the four combined Einstein@home runs on S6 LIGO data are out: Results of the deepest all-sky survey for continuous gravitational waves on LIGO S6 data running on the Einstein@Home volunteer distributed computing project

We will shortly also submit the paper for publication in Physical Review D, but we wanted to share these results with you immediately. We have not yet found a gravitational wave signal but we could bound the height of mountains on neutron stars in the neighbourhood of Earth. For example, we can now say that there is no neutron star spinning at 9 ms or faster within 100 parsecs of Earth with a bump higher than 1 cm!

On behalf of M. Alessandra Papa for the Einstein@Home team

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Mike Hewson
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Results of the deepest all-sky survey for continuous gravitation

Cool. E@H rocks ! :-))

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

cal_grufti
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Smooth

Smooth

Sir Thomas W. Kilburn
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that makes my computers and

that makes my computers and me happy

AgentB
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This made me first think

This made me first think there's probably no neutron stars nearby.

So I did some on the back of a beer mat maths.

The stellar density in our Milky way backwater is 0.14 stars / cubic parsec (pc) (*) So 100pc radius sphere should have 4/3 * 3.14 * 100^3 * 0.14 = 586000 stars. I seem to remember reading about 1 in a 1000 (?) stars in the Milky Way is thought to be a neutron star, so there would be about 500-600 neutron stars in that sphere.

Which is a lot lot more than i first thought.

Thanks Oliver and the E@H team, it's really impressive we have results only a few months after the first "light".

(*) I didn't know that i looked it up in wikipedia.

Bikeman (Heinz-Bernd Eggenstein)
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RE: it's really impressive

Quote:
it's really impressive we have results only a few months after the first "light".

It's worth noting tho that these are still results from LIGO S6 data, so not yet the data set of the AdvancedLIGO detectors that saw "first light" last year. With every improvement in detector sensitivity [*] by a factor of k, we increase the volume of space we can make such statements about by a factor of k^3 (!!), so you can imagine that results from the O1 dataset will be even more interesting (even if no signal should be found).

[*] as measured in the fractional change of the detector arm lengths due to GWs we can detect, put simply.

robl
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Einstein@Home is a project

Einstein@Home is a project that offers rewards to its participants far greater than credits. To know, to participate in and to contribute to a project that has already produced positive results and will produce more results is an incredible experience. I feel fortunate to be part of this effort with all of you.

poppageek
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It is great to be on a

It is great to be on a winning team. :-)

Cheers!

maydragon
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Cheer, Einstein@Home

Cheer, Einstein@Home team.
That is "spheroid"!

DanNeely
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How much, if at all, does

How much, if at all, does this constrain known neutron stars; as opposed to saying that either any NSes near Earth are either extremely flat compared to predictions of perhaps a few meters for mountains or old enough to be spinning very slowly?

ex I remember seeing a poster LIGO put our years ago that showed the Crab Nebula Pulsar as one of the most likely detection candidates; and it's ~2000 parsecs>

Jim1348
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RE: The stellar density in

Quote:
The stellar density in our Milky way backwater is 0.14 stars / cubic parsec (pc) (*) So 100pc radius sphere should have 4/3 * 3.14 * 100^3 * 0.14 = 586000 stars. I seem to remember reading about 1 in a 1000 (?) stars in the Milky Way is thought to be a neutron star, so there would be about 500-600 neutron stars in that sphere.


In that case, what is the chance of detecting "mountains" on neutron stars further out? Isn't 500-600 stars a pretty good sample set?

astro-marwil
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Hallo Dan! RE: ...the

Hallo Dan!

Quote:
...the Crab Nebula Pulsar as one of the most likely detection candidates...


There was a carefull analysis of data from the LIGO S5 run for the Crab Pulsar. Taking into account the 20 fold distance of the Crab and the 1/r^2 law, they come to a comparable value. The difficulty for pulsars is, to separate between the energy loss due to electromagnetic and gravitational energy loss.
I believe, they will repeat this analysis once with data from aLIGO.

Kind regards and happy crunching
Martin

Bikeman (Heinz-Bernd Eggenstein)
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RE: Hallo Dan!RE: ...the

Quote:
Hallo Dan!
Quote:
...the Crab Nebula Pulsar as one of the most likely detection candidates...

There was a carefull analysis of data from the LIGO S5 run for the Crab Pulsar. Taking into account the 20 fold distance of the Crab and the 1/r^2 law, they come to a comparable value. The difficulty for pulsars is, to separate between the energy loss due to electromagnetic and gravitational energy loss.
I believe, they will repeat this analysis once with data from aLIGO.

Kind regards and happy crunching
Martin

A more recent analysis on known pulsars, already including LIGO S6 data, is discussed in this paper: https://arxiv.org/abs/1309.4027

As for

Quote:
the 1/r^2 law

one has to be careful. The quantity that is usually used to describe the "strength" of a GW and also the sensitivity of our detectors, the "strain amplitude", scales like 1/r with distance to the source, not 1/r^2.

HB

Sir Thomas W. Kilburn
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if it works. it works.

if it works. it works.