What's the sensitivity of Ligo?

David Gumina
David Gumina
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Topic 191880

How far out can it detect black hole mergers? and has it continued increasing it's sensitivity? Apart from Ligo 2, does Ligo continue to improve?

debugas
debugas
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What's the sensitivity of Ligo?

when i started crunching about a year and a half ago i was crunching S3 workunits and now we are crunching running S5

The sensitivity of LIGO was increasing each time switching first from S3 to S4 and then from S4 to S5. Now as far as i understand S5 is the data that has the originally projected sensitivity level for LIGO

Mike Hewson
Mike Hewson
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RE: How far out can it

Quote:
How far out can it detect black hole mergers? and has it continued increasing it's sensitivity?


That would 'depend', but it would seem to be about 45 million light years. See here.
Cheers, Mike.

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

David Gumina
David Gumina
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So there won't be any

So there won't be any increases in sensitivity until Advanced LIGO then?

Thanks Mike. Had a look at LIGO's logs and the Inspiral Range is around 14-15 Mpc if I read it correctly.

Mike Hewson
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RE: So there won't be any

Message 47349 in response to message 47348

Quote:
So there won't be any increases in sensitivity until Advanced LIGO then?


No major leaps in sensitivity 'til then. It's currently running at the design spec, give or take a tad. A major focus is keeping the LIGO's up & locked simultaneously for as large a fraction of the time as possible.

Quote:
Thanks Mike. Had a look at LIGO's logs and the Inspiral Range is around 14-15 Mpc if I read it correctly.

Yes, the correct multiplier is about 3.26 light years to the parsec ..... :-)
That figure is based upon a 'standard' inspiral event - I'll see if I can find out more exactly how that is defined.
Cheers, Mike.

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

Ben Owen
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Hi folks, S5 has hit (or

Hi folks,

S5 has hit (or even slightly exceeded) the design sensitivity. It is staying that way for another year or so. Advanced LIGO (what you are calling LIGO 2) will have strain noise improved by a factor of about 10, but it won't get fully running for the better part of a decade. In the meantime there may be a small upgrade of about a factor of 2 in strain.

The range figure you see in the logs is for an optimally oriented binary with an amplitude signal-to-noise ratio of 8 (after matched filtering). Both objects in the binary are assumed to be 1.4 times as massive as the sun, which is a typical mass for neutron stars.

The range for black holes is trickier. It depends on the masses. While neutron stars don't deviate too much from 1.4 solar masses, black holes have been measured to be much heavier and cover a range of masses. If the sum of the two masses is up to about 20 solar masses, the range (for fixed signal-to-noise) goes up roughly as the 5/3 power of the total mass. But then it starts going down again as you increase the mass, because the merger cuts off at a lower frequency (inversely proportional to total mass) and eventually goes out of LIGO's frequency band altogether.

The technical article on the S2 black hole search is here. It was written for other physicists rather than a general audience, but the section on target sources is relatively free of equations and jargon and is related to your question.

Hope this helps,

Ben

Mike Hewson
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RE: Hi folks ....... Hope

Message 47351 in response to message 47350

Quote:
Hi folks ....... Hope this helps,
Ben


Indeed it does! Thanks for that, and the link :-)
Cheers, Mike.

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

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