APOD: Black Holes of Known Mass (2017 Jun 02)

[APOD Robot]

Black Holes of Known Mass

Explanation: Add GW170104 to the chart of black holes with known mass. The extremely energetic merger of two smaller black holes corresponds to the Laser Interferometer Gravitational-wave Observatory's (LIGO) third detection of gravitational waves. The newfound black hole has a mass about 49 times that of the Sun, filling a gap between the masses of the two merged black holes detected previously by LIGO, with solar masses of 62 (GW150914) and 21 (GW151226). In all three cases, the signal in each of the twin LIGO detectors was unambiguously identified as coming from black hole mergers while a fourth case (LVT151012) resulted in a lower confidence detection. GW170104 is estimated to be some 3 billion light-years away, more distant than present estimates for GW150914 and GW151226. The ripples in spacetime were discovered during LIGO's current observing run, which began November 30, 2016 and will continue through the summer.

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[bystander]

http://asterisk.apod.com/viewtopic.php?t=37239

[Ann]

It is satisfying to see more gravtitational waves detected from merging black holes, and still more confirmation of the predictions made by general relativity.

Ann

[Blastov]

This was again a merger of a "medium size" class of black holes. If there were a merger of "supermassive" black holes, on the order of many millions of solar masses, would LIGO be calibrated to measure it? Could a "supermassive" merger be theoretically powerful enough that we would detect it in other ways? might we "sense" such an event? Could a "mega gravity tsunami" cause problems for us on earth? i'm imagining anything from momentarily haywire bathroom scales to global seismic cataclysm from core destabilization, or other possible "gravity problems". I would hate to have a " bad gravity day"

[Blastov]

sorry, make that "gravitational tsunami"

[Boomer12k]

Seems to be a simple addition problem...

So.... can we "surf" to Alpha Centauri on one?

:---[===] *

[Case]

So.... can we "surf" to Alpha Centauri on one?

Math homework problem: how close does a black hole merger have to be, to create a wave strong enough that a space ship from Earth can ride it to the next star? As the wave is directional, how much steering is possible? How do we get off the wave at our destination?

[Ann]

So.... can we "surf" to Alpha Centauri on one?

Math homework problem: how close does a black hole merger have to be, to create a wave strong enough that a space ship from Earth can ride it to the next star? As the wave is directional, how much steering is possible? How do we get off the wave at our destination?

Reminds me of the age-old question: How do you get off at the right destination if you dive head first into a black hole in the hopes of finding a wormhole teleporter?

And how do you avoid getting spaghettified or turned into a seriously tenderized slab of meat if you get really close and personal with the black hole itself, or if you hitch a ride on the incredibly powerful gravitational waves generated by a really nearby black hole merger?

Ann

[distefanom]

I'm impressed about the so called "sensitivity" of the LIGO interferometer, and have a couple of questions:

1) I think that only an handful of events detected, are too few for such a sensitive instrument.
I think in the space around us (i.e. our own galaxy), should be way more smaller black holes, gliding around around and (maybe) way more often,that gigantic solar masses collide to form black holes, so one should expect a "background noise" way higher than the one detected?

2) If it ìs true that Several times the sun size black holes can be detected so far away in space & time... How we can be sure that the "ringing" LIGO detects is due to this kind of mass collision?
Conseguently, I've doubts that LIGO is detecting ALSO SOMETHING ELSE.

[MountainJim]

Interesting but I was hoping to see more Blue & Yellow tits.

[neufer]

This was again a merger of a "medium size" class of black holes. If there were a merger of "supermassive" black holes, on the order of many millions of solar masses, would LIGO be calibrated to measure it? Could a "supermassive" merger be theoretically powerful enough that we would detect it in other ways? might we "sense" such an event? Could a "mega gravity tsunami" cause problems for us on earth? i'm imagining anything from momentarily haywire bathroom scales to global seismic cataclysm from core destabilization, or other possible "gravity problems". I would hate to have a " bad gravity day"

The merger of two 40 solar mass black holes is in the 100 Hz sweet spot of Advanced LIGO.

The slow merger of two 2,000,000 solar mass black holes would be in the 2 milli-Hz sweet spot of a space based LISA detector.

There is too much wind, geothermal, man-made and ocean wave noise at 2 milli-Hz to make use of a ground based detector.

[b][color=#0000FF]Noise curves for a selection of gravitational-wave detectors as a function of frequency. At very low frequencies are pulsar timing arrays, the European Pulsar Timing Array (EPTA) and the future International Pulsar Timing Array (IPTA); at low frequencies are space-borne detectors, the formerly proposed Laser Interferometer Space Antenna (LISA) and the currently proposed evolved Laser Interferometer Space Antenna (eLISA), and at high frequencies are ground-based detectors, the initial Laser Interferometer Gravitational-Wave Observatory (LIGO) and its advanced configuration (aLIGO). The characteristic strain of potential astrophysical sources are also shown. To be detectable the characteristic strain of a signal must be above the noise curve.[/color][/b]

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<<Gravitational waves can be emitted by many systems, but, to produce detectable signals, the source must consist of extremely massive objects moving at a significant fraction of the speed of light. The main source is a binary of two compact objects. Example systems include:

Compact binaries made up of two closely orbiting stellar-mass objects, such as white dwarfs, neutron stars or black holes. Wider binaries, which have lower orbital frequencies, are a source for detectors like LISA. Closer binaries produce a signal for ground-based detectors like LIGO. Ground-based detectors could potentially detect binaries containing an intermediate mass black hole of several hundred solar masses.
Supermassive black hole binaries, consisting of two black holes with masses of 10⁵–10⁹ solar masses. Supermassive black holes are found at the centre of galaxies. When galaxies merge, it is expected that their central supermassive black holes merge too. These are potentially the loudest gravitational-wave signals. The most massive binaries are a source for PTAs. Less massive binaries (about a million solar masses) are a source for space-borne detectors like LISA.
Extreme-mass-ratio systems of a stellar-mass compact object orbiting a supermassive black hole. These are sources for detectors like LISA. Systems with highly eccentric orbits produce a burst of gravitational radiation as they pass through the point of closest approach; systems with near-circular orbits, which are expected towards the end of the inspiral, emit continuously within LISA's frequency band. Extreme-mass-ratio inspirals can be observed over many orbits. This makes them excellent probes of the background spacetime geometry, allowing for precision tests of general relativity.

In addition to binaries, there are other potential sources:

• Supernovae generate high-frequency bursts of gravitational waves that could be detected with LIGO or Virgo.
  Rotating neutron stars are a source of continuous high-frequency waves if they possess axial asymmetry.
  Early universe processes, such as inflation or a phase transition.
  Cosmic strings could also emit gravitational radiation if they do exist. Discovery of these gravitational waves would confirm the existence of cosmic strings.

Gravitational waves interact only weakly with matter. This is what makes them difficult to detect. It also means that they can travel freely through the Universe, and are not absorbed or scattered like electromagnetic radiation. It is therefore possible to see to the center of dense systems, like the cores of supernovae or the Galactic Centre. It is also possible to see further back in time than with electromagnetic radiation, as the early universe was opaque to light prior to recombination, but transparent to gravitational waves.

The ability of gravitational waves to move freely through matter also means that gravitational-wave detectors, unlike telescopes, are not pointed to observe a single field of view but observe the entire sky. Detectors are more sensitive in some directions than others, which is one reason why it is beneficial to have a network of detectors.>>

[Chris Peterson]

This was again a merger of a "medium size" class of black holes. If there were a merger of "supermassive" black holes, on the order of many millions of solar masses, would LIGO be calibrated to measure it?

No. The length of LIGO's arms and other physical constraints make it responsive to gravitational waves in the 10-1000 Hz range. Sources that produce such frequencies include supernovas and small black hole inspirals. Supermassive black hole inspirals produce signals in the millihertz range, requiring interferometer arms on the order of a million kilometers long- e.g. space-based detectors like LISA. Extremely massive inspirals producing microhertz to nanohertz signals might be detected by using radio telescopes to measure pulsar timing.

Could a "supermassive" merger be theoretically powerful enough that we would detect it in other ways? might we "sense" such an event? Could a "mega gravity tsunami" cause problems for us on earth? i'm imagining anything from momentarily haywire bathroom scales to global seismic cataclysm from core destabilization, or other possible "gravity problems". I would hate to have a " bad gravity day"

No. The spacetime distortion from even the most massive events is still subatomic in spatial scale.

[Fred the Cat]

I can hardly wait to see the "next" article. I like twists.

How fun would it be if rotation through us a curve?

[Chris Peterson]

I think in the space around us (i.e. our own galaxy), should be way more smaller black holes, gliding around around and (maybe) way more often,that gigantic solar masses collide to form black holes, so one should expect a "background noise" way higher than the one detected?

LIGO is only sensitive to the inspiral of medium mass black holes. It cannot detect individual black holes of any mass, so any that might be around us would have no effect (and solar mass black holes are gravitationally no different than stars, in any case).

2) If it ìs true that Several times the sun size black holes can be detected so far away in space & time... How we can be sure that the "ringing" LIGO detects is due to this kind of mass collision?

The complex details of the gravitational wave waveform recorded by LIGO (that is, the time-dependent change in both amplitude and frequency) are exactly described by General Relativity. That's extremely strong evidence that we're observing black hole inspirals (and there are no alternative explanations at all).

[douglas]

" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

[Chris Peterson]

" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

Not sure what you're trying to say here. However, the three detections range from z=0.09 to z=0.2, corresponding to light travel times of 1-2.5 billion years and luminosity distances of 1-2.5 Gly. These inspirals occurred quite nearby in comparison to the edge of the observable universe (z>1100, light travel time 13.7 billion years).

[neufer]

So.... can we "surf" to Alpha Centauri on one?

Math homework problem: how close does a black hole merger have to be, to create a wave strong enough that a space ship from Earth can ride it to the next star? As the wave is directional, how much steering is possible? How do we get off the wave at our destination?

The best emitter of gravitational waves is a close circularly orbiting binary pair of neutron stars or black holes.

Likewise, the best absorber of such gravitational waves is a matching identical adjacent close circular orbiting binary pair of neutron stars or black holes.

(Note, however, that a close elliptically orbiting mismatched binary pair of neutron stars or black holes can self propel itself.)

Even in such extreme cases the reaction motions are no where near relativistic.

Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved (i.e., momentum impulse = 2E/c). Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved (i.e., momentum impulse = E/c).

[Ann]

Art wrote:
Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved. Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved.

Ah! So we will have to dive head first into black holes in the hopes of finding wormholes inside, then!

Ann

[neufer]

Art wrote:

Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved (i.e., momentum impulse = 2E/c). Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved (i.e., momentum impulse = E/c).

Ah! So we will have to dive head first into black holes in the hopes of finding wormholes inside, then!

That's what Darwin ended up doing:

https://en.wikipedia.org/wiki/The_Forma ... n_of_Worms

(... and worms are pre-spaghettified.)

[douglas]

Art wrote:
Light sails take maximal advantage (i.e., almost total reflection) of the free massless particles impinging on them but are extremely inefficient in making use of the energies involved. Gravitational wave sails take minimal advantage (i.e., almost total transparency) of the free massless particles impinging on them and they are equally inefficient in making use of the energies involved.

Ah! So we will have to dive head first into black holes in the hopes of finding wormholes inside, then!

Ann

Would any human-protective technology powerful enough to resist tides also make it impossible to use a wormhole?

[douglas]

" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

Not sure what you're trying to say here. However, the three detections range from z=0.09 to z=0.2, corresponding to light travel times of 1-2.5 billion years and luminosity distances of 1-2.5 Gly. These inspirals occurred quite nearby in comparison to the edge of the observable universe (z>1100, light travel time 13.7 billion years).

If I'm reading physorg right, general relativity forbids any modification to these waves at any distance:

" .. The study also once again puts Albert Einstein's theories to the test. For example, the researchers looked for an effect called dispersion, which occurs when light waves in a physical medium such as glass travel at different speeds depending on their wavelength; this is how a prism creates a rainbow. Einstein's general theory of relativity forbids dispersion from happening in gravitational waves as they propagate from their source to Earth. LIGO did not find evidence for this effect.

"It looks like Einstein was right—even for this new event, which is about two times farther away than our first detection," says Laura Cadonati of Georgia Tech and the Deputy Spokesperson of the LSC. "We can see no deviation from the predictions of general relativity, and this greater distance helps us to make that statement with more confidence."

Read more at: https://phys.org/news/2017-06-gravitati ... s.html#jCp

[csw]

Does LIGO offer us evidence of the direction the waves came from? We know the merged black holes are X light years away, but do we know where they are? Just curious.

[Chris Peterson]

" .. LIGO's current observing run .. began November 30, 2016 .. "

That detection rate from the edge of the observable universe implies The Big Crunch is a LONG ways away.
The Big Crunch Evaporation strikes again?

Not sure what you're trying to say here. However, the three detections range from z=0.09 to z=0.2, corresponding to light travel times of 1-2.5 billion years and luminosity distances of 1-2.5 Gly. These inspirals occurred quite nearby in comparison to the edge of the observable universe (z>1100, light travel time 13.7 billion years).

If I'm reading physorg right, general relativity forbids any modification to these waves at any distance:

I'm not sure what you mean by that. GR forbids dispersion. That says nothing about gravitational waves being modified.

That said, I don't understand the connection between your earlier post and this one.

[Chris Peterson]

Does LIGO offer us evidence of the direction the waves came from? We know the merged black holes are X light years away, but do we know where they are? Just curious.

Yes, the direction can be estimated. LIGO currently consists of two detectors, one in Washington and one in Louisiana. Together, the detectors form a gravitational wave telescope. By comparing the timing and phase relationship between coincident events at the two detectors, it is possible to constrain the source to a specific band of the sky. They play other tricks with the interferometric signal itself to further narrow the direction.

Eventually, as more detectors are added (such as the Virgo system soon coming online in Europe), the direction will be finely determined for most events.

[neufer]

Does LIGO offer us evidence of the direction the waves came from? We know the merged black holes are X light years away, but do we know where they are? Just curious.

The time delay between the two operating sites isolates the source to a broad circle or arc in the sky.

When there are three or more operating sites the intersection of the three or more sky circles will give us a much more well defined direction.