Why Does LIGO Only Detect the Famous 'Chirp' Pulse from Black Hole Mergers?

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Discussion Overview

The discussion centers around the detection of gravitational waves by LIGO, specifically focusing on why only the 'chirp' pulse from black hole mergers is prominently reported in media. Participants explore the frequency of black hole mergers, the characteristics of the detected signals, and the operational aspects of LIGO.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants question why LIGO only detects the 'chirp' pulse and suggest that there should be more signals if the detector is functioning as intended.
  • Others propose that the rarity of black hole mergers contributes to the limited number of detected signals.
  • There is a discussion about whether the detection of the wavefront was a matter of luck or if LIGO was designed with such events in mind.
  • Some participants argue that LIGO's sensitivity has improved over time, making the detection of gravitational waves more likely.
  • Questions are raised about the operational status of LIGO and whether future detections will be targeted or opportunistic.
  • Participants discuss the implications of mass similarity in black hole mergers on the strength of the detected signals, suggesting that larger mass differentials may produce weaker signals.
  • There is mention of the potential for future space-based detectors like LISA to detect more frequent gravitational waves from smaller mergers, contrasting with LIGO's capabilities.

Areas of Agreement / Disagreement

Participants express differing views on the frequency of black hole mergers and the implications for LIGO's detection capabilities. There is no consensus on whether the detection of the chirp pulse was purely luck or indicative of the commonality of such events.

Contextual Notes

Some participants note that the understanding of gravitational wave detection is still evolving, particularly regarding the characteristics of black hole mergers and the operational parameters of LIGO.

Who May Find This Useful

This discussion may be of interest to those studying gravitational waves, astrophysics, or the operational aspects of experimental physics related to LIGO and future detectors.

houlahound
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Is another subforum for Ligo, I see nothing in here(?

My main question is on all the popular media reports i have only seen the one pulse, the now famous chirp If the thing works why isn't it swamped with signals??
 
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houlahound said:
Is another subforum for Ligo, I see nothing in here(?
If we had one subforum for every experiment, they would be impossible to find.

houlahound said:
My main question is on all the popular media reports i have only seen the one pulse, the now famous chirp If the thing works why isn't it swamped with signals??
Because there are neot that many black hole mergers.
 
Is it the pulse of the wavefront that was measured as it swept past LIGO. has that signal moved past the Earth forever now. Was it luck that the age/distance/speed of the wave coincided with LIGO ready to measure or was LIGO built to a schedule with this transmission in mind??
 
Yes, a black hole merger is a rather short affair. The signal from the particular merger that was observed is now almost half a light year away.

It was "luck" for this particular event. LIGO was built to measure events of this type, not necessarily that event.
 
Talk about frikkin luck then, no wonder that team was doing the happy dance.

Does this cause a problem for verifying the signal, I mean one, correction, two coincident signals would not instill me with a lot of confidence but I ain't no genius.

Does this open up a lot of tests for age of galaxies that can now be tested directly given distance and tra el times?
 
houlahound said:
Talk about frikkin luck then, no wonder that team was doing the happy dance.
No, it is not "frikkin luck". Did you not read what I said? LIGO was built to see this type of event and the fact that they already saw one is likely an indicator that they are relatively common. If not this particular one, it is likely another would have come.

It is also not as if LIGO exists in a setting with no other experiments. Gravitational wave detectors have been increasing in sensitivity over the years and were now finally sensitive enough to make the discovery.
 
How long was this particular LIGO measurement detector ready and why haven't there been any other activity since, is it off line.

Is the next measurement going to be expected from a target or justvwait for a event and figure what caused it?
 
Is my understanding correct, that it is due to both the similarity to each other in mass as well as the range of their masses, 10s of stellar mass, that it produced a "nice" signal for detection by LIGO, and that mergers between BH-mass objects with a higher differential, say one at 10 SM and one at 75-100 SM, would not result in as large of a signal when they merged? Presumably we are reviewing our models of likelyhoods that mergers like this will happen, my first impression of LIGO was, apart from the GW detection, that the BHs involved were far more rare than those nearly an order of magnitude smaller.
 
krater said:
Is my understanding correct, that it is due to both the similarity to each other in mass as well as the range of their masses, 10s of stellar mass, that it produced a "nice" signal for detection by LIGO, and that mergers between BH-mass objects with a higher differential, say one at 10 SM and one at 75-100 SM, would not result in as large of a signal when they merged? Presumably we are reviewing our models of likelyhoods that mergers like this will happen, my first impression of LIGO was, apart from the GW detection, that the BHs involved were far more rare than those nearly an order of magnitude smaller.

Apparently LIGO technology can detect the far Less Frequent LARGER Mergers
compared to future Space Based LISA
according to this chart their sensitivity to various Frequensies do Not overlap much if at all. **

https://en.wikipedia.org/wiki/Evolved_Laser_Interferometer_Space_Antenna

The next article indicates Thousands of GWs
will be detected from smaller binary Mergers in our own Galaxie, by eLISA.

While LIGO has detected only 1 GW from over 1000 Light Years away,
with rumors of maybe a few more since then that are still being verified.

https://www.elisascience.org/articles/science-context-2028/astrophysics-stars-and-galaxy-2028

** Their discussion of collaborative Observations by LIGO, LISA, ET and others
of a single Merger of Super Massive Black Holes ( very rare )
makes me sure I do not understand all I know about the above.
 

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