Chandra 'Hears' A Black Hole

Donald Savage
Headquarters, Washington
(Phone: 202/358-1727) September 9, 2003

Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-6535)

Megan Watzke
Chandra X-ray Observatory Center, CfA, Cambridge, Mass.
(Phone: 617/496-7998)

RELEASE: 03-284

CHANDRA "HEARS" A BLACK HOLE

NASA's Chandra X-ray Observatory detected sound waves,
for the first time, from a super-massive black hole. The
"note" is the deepest ever detected from an object in the
universe. The tremendous amounts of energy carried by these
sound waves may solve a longstanding problem in
astrophysics.

The black hole resides in the Perseus cluster, located 250
million light years from Earth. In 2002, astronomers
obtained a deep Chandra observation that shows ripples in
the gas filling the cluster. These ripples are evidence for
sound waves that have traveled hundreds of thousands of
light years away from the cluster's central black hole.

"We have observed the prodigious amounts of light and heat
created by black holes, now we have detected the sound,"
said Andrew Fabian of the Institute of Astronomy (IoA) in
Cambridge, England, and leader of the study.

In musical terms, the pitch of the sound generated by the
black hole translates into the note of B flat. But, a human
would have no chance of hearing this cosmic performance,
because the note is 57 octaves lower than middle-C (by
comparison a typical piano contains only about seven
octaves). At a frequency over a million, billion times
deeper than the limits of human hearing, this is the deepest
note ever detected from an object in the universe.

"The Perseus sound waves are much more than just an
interesting form of black hole acoustics," said Steve Allen,
also of the IoA and a co-investigator in the research.
"These sound waves may be the key in figuring out how galaxy
clusters, the largest structures in the universe, grow,"
Allen said.

For years astronomers have tried to understand why there is
so much hot gas in galaxy clusters and so little cool gas.
Hot gas glowing with X-rays should cool, and the dense
central gas should cool the fastest. The pressure in this
cool central gas should then fall, causing gas further out
to sink in towards the galaxy, forming trillions of stars
along the way. Scant evidence has been found for such a flow
of cool gas or star formation. This forced astronomers to
invent several different ways to explain why the gas
contained in clusters remained hot, and, until now, none of
them was satisfactory.

Heating caused by a central black hole has long been
considered a good way to prevent cluster gas from cooling.
Although jets have been observed at radio wavelengths, their
effect on cluster gas was unclear since this gas is only
detectable in X-rays, and early X-ray observations did not
have Chandra's ability to find detailed structure.

Previous Chandra observations of the Perseus cluster showed
two vast, bubble-shaped cavities in the cluster gas
extending away from the central black hole. Jets of material
pushing back the cluster gas have formed these X-ray
cavities, which are bright sources of radio waves. They have
long been suspected of heating the surrounding gas, but the
mechanism was unknown. The sound waves, seen spreading out
from the cavities in the recent Chandra observation, could
provide this heating mechanism.

A tremendous amount of energy is needed to generate the
cavities, as much as the combined energy from 100 million
supernovae. Much of this energy is carried by the sound
waves and should dissipate in the cluster gas, keeping the
gas warm and possibly preventing a cooling flow. If so, the
B-flat pitch of the sound wave, 57 octaves below middle-C,
would have remained roughly constant for about 2.5 billion
years.

Perseus is the brightest cluster of galaxies in X-rays, and
therefore was a perfect Chandra target for finding sound
waves rippling through the hot cluster gas. Other clusters
show X-ray cavities, and future Chandra observations may yet
detect sound waves in these objects.

For images and additional information on the Internet,
visit:

http://chandra.nasa.gov

http://chandra.harvard.edu


-end-

On a sunny day (9 Sep 2003 18:59:12 GMT) it happened
(Ron Baalke) wrote in
:

If so, the
B-flat pitch of the sound wave, 57 octaves below middle-C,
would have remained roughly constant for about 2.5 billion
years.
Is it out of order to just write a frequency in Hz?
Like nn Hz? (maybe float).
At least I would have some idea.
Or how about 'radio waves that are 57 octaves below
the resonance of .3 mm thick quarts?'
If you wanted to be cryptic you succeeded.

Jan Panteltje responded to a press release:

If so, the B-flat pitch of the sound wave, 57 octaves below
middle-C, would have remained roughly constant for about
2.5 billion years.

Is it out of order to just write a frequency in Hz?
Like nn Hz? (maybe float).
At least I would have some idea.

Middle C has a frequency of 261.63 Hz. The B-flat just below
it has a frequency of 233.08 Hz. An octave is a doubling or
halving of frequency, so 57 octaves below the B-flat just below
middle C is 1.6 e-15 Hz, if I calculated correctly. That is a
period of 618,307,825,964,715 seconds, or 19,592,992 years,
again if I calculated correctly.

Makes no sense to me.

-- Jeff, in Minneapolis

..

On 9 Sep 2003 20:40:34 -0700, in sci.astro, (Jeff Root)
wrote:

Jan Panteltje responded to a press release:

If so, the B-flat pitch of the sound wave, 57 octaves below
middle-C, would have remained roughly constant for about
2.5 billion years.

Is it out of order to just write a frequency in Hz?
Like nn Hz? (maybe float).
At least I would have some idea.

Middle C has a frequency of 261.63 Hz. The B-flat just below
it has a frequency of 233.08 Hz. An octave is a doubling or
halving of frequency, so 57 octaves below the B-flat just below
middle C is 1.6 e-15 Hz, if I calculated correctly. That is a
period of 618,307,825,964,715 seconds, or 19,592,992 years,
again if I calculated correctly.

Makes no sense to me.

Sound = pressure waves = mechanical/kenetic energy...

They are observing a periodic pressure wave... as the gases are flowing
outward from the black hole. Calling such pressure waves is not really
accurate...

Sound is a mechanical wave, so them calling this periodic wave sound is
really reaching.


--
Aktohdi

Jeff Root wrote:

Middle C has a frequency of 261.63 Hz. The B-flat just below
it has a frequency of 233.08 Hz. An octave is a doubling or
halving of frequency, so 57 octaves below the B-flat just below
middle C is 1.6 e-15 Hz, if I calculated correctly. That is a
period of 618,307,825,964,715 seconds, or 19,592,992 years,
again if I calculated correctly.

A bit generous with our precision, aren't we?

Makes no sense to me.

Well, sound waves are just longitudinal pressure waves through a
medium, yes? In a sense, what this black hole is throwing out could be
seen as such (as the original article stated, "ripples in the gas
filling the cluster")... though a period of 19.6 million years seems to
stretch the idea of "sound" to the breaking point. -=shrug=-
--
-- With Best Regards,
Matthew Funke )

Well, sound waves are just longitudinal
pressure waves through a medium, yes?
In a sense, what this black hole is
throwing out could be seen as such (as
the original article stated, "ripples in the
gas filling the cluster")... though a period
of 19.6 million years seems to stretch
the idea of "sound" to the breaking point. -=3Dshrug=3D-
--
With Best Regards,
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0Matthew
Funke

They'e picturing it as sound propagating thru interstellar gas at some
sonic velocity. Since space itself is 'pure void', there is no other
mechanism of transmission. So what's being transmitted is "phonons".g

But suppose space is *not* a void but a compressible, expansible fluid
medium. Those compression-rarefaction waves are (predominantly) in the
fabric of space itself, propagating at c, otherwise known as 'gravity
waves'.

Since the mainstream recognizes no underlying spatial medium (or VED),
it must picture the waves as predominantly sonic waves in interstellar
gas.
oc

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Bob Officer replied to Jeff Root:

Middle C has a frequency of 261.63 Hz. The B-flat just below
it has a frequency of 233.08 Hz. An octave is a doubling or
halving of frequency, so 57 octaves below the B-flat just below
middle C is 1.6 e-15 Hz, if I calculated correctly. That is a
period of 618,307,825,964,715 seconds, or 19,592,992 years,
again if I calculated correctly.

Makes no sense to me.

Sound = pressure waves = mechanical/kenetic energy...

They are observing a periodic pressure wave... as the gases are
flowing outward from the black hole. Calling such pressure waves

Did you accidentally omit the word "sound" at this point?

is not really accurate...

Sound is a mechanical wave, so them calling this periodic wave
sound is really reaching.

I assume that they know what sound is and what it isn't. Since
they call it "sound", I assume it is a correct use of the term.

What makes no sense to me is: How can it have a period of
19 million years?

-- Jeff, in Minneapolis

..

Jeff Root wrote:

What makes no sense to me is: How can it have a period of
19 million years?

Do you know of something that would keep it from having such a
period? I'd be interested in how they measure the waves' speed of
propagation. Once you have *that*, and you can see the ripples (which the
article states Chadra "saw"), it seems to me that determining the period
is trivial. The animations at the following URL might help you visualize
how these ripples propagate, though I'm still trying to look up the
physics behind the matter:

http://www1.msfc.nasa.gov/NEWSROOM/news/video/2003/video03-152.html

This link will show you photographs where they determine the ripples
are located:

http://www1.msfc.nasa.gov/NEWSROOM/news/photos/2003/photos03-152.html
--
-- With Best Regards,
Matthew Funke )

Matthew F Funke wrote:

This link will show you photographs where they determine the ripples
^^^^^^^^^^^^^^^^^

Whoops! Make that "photographs *of* where".
--
-- With Best Regards,
Matthew Funke )

What makes no sense to me is: How can it have a period of 19 million
years?
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0
If it turns out those "sound" waves are predominantly gravity waves
propagating at c, their period will be tremendously shorter.
It may one day be determined that the great 'sheets and
voids' structuring of the galactic supercluster field may be driven by
very long-period gravity waves from the BB itself.
oc

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