[Fwd: Dark Matter: black hole frame drag?]

Discussion:

(too old to reply)

Jeff Bucove

2004-11-27 01:39:11 UTC

-------- Original Message --------
Subject: Dark Matter: black hole frame drag?
Date: Fri, 26 Nov 2004 17:31:50 -0800
From: Jeff Bucove <***@telus.net>
Newsgroups: alt.astronomy

I have always had a problem with the dark matter thing. As an
explanation for too much "apparent" gravitational force at galactic
scales it sucks.

I have always been sure that there is an observational problem
involving unknown forces at great distance or other as yet to be
discovered phenomena.

I have recently learned through public media that the spinning super
sized black hole at the center of our Galaxy has an angular velocity at
the event horizon of 1/3 the speed of light, or C/3.

I am posting to ask authoritative astronomers this question:

Could the relativistic frame drag of an object this massive spinning at
this speed generate enough spiral warpage of space-time to account for
the observed clustering of matter on galactic scales?

...jeffery

nightbat

2004-11-27 08:05:45 UTC

Permalink

Post by Jeff Bucove
-------- Original Message --------
Subject: Dark Matter: black hole frame drag?
Date: Fri, 26 Nov 2004 17:31:50 -0800
Newsgroups: alt.astronomy
I have always had a problem with the dark matter thing. As an
explanation for too much "apparent" gravitational force at galactic
scales it sucks.
I have always been sure that there is an observational problem
involving unknown forces at great distance or other as yet to be
discovered phenomena.
I have recently learned through public media that the spinning super
sized black hole at the center of our Galaxy has an angular velocity at
the event horizon of 1/3 the speed of light, or C/3.
Could the relativistic frame drag of an object this massive spinning at
this speed generate enough spiral warpage of space-time to account for
the observed clustering of matter on galactic scales?
...jeffery

nightbat

Well Jeff locally does the sun have an gravitational effect on
our planet even though it is many space miles away from it? Then imagine
an object with many times the solar body count composite of our sun, how
much of a theoretical strong gravity field non relativistic frame drag
pull should it have? Relativity stops at the gates of hyper strong
gravity fields, for the inverse gravitational pull of the nightbat "
Black Comet " tail is one way until it is ejected out of the galactic
mother in which it formed.

the nightbat

Double-A

2004-11-27 17:22:47 UTC

Permalink

An interesting consideration.

I don't know about the clustering, but the frame dragging influence
from a massive black hole might affect the galaxy such that the
galactic spin might appear to be faster than what gravity could
account for, if the rotation of the black hole were in the same
direction as the galactic rotation. And isn't this exactly what is
being observed?

The only question would be how far the influence of the black hole's
frame dragging would extend.

Arlyn

Jumpin Jeff

2004-11-27 19:54:01 UTC

Permalink

Post by Double-A

An interesting consideration.
I don't know about the clustering, but the frame dragging influence
from a massive black hole might affect the galaxy such that the
galactic spin might appear to be faster than what gravity could
account for, if the rotation of the black hole were in the same
direction as the galactic rotation. And isn't this exactly what is
being observed?
The only question would be how far the influence of the black hole's
frame dragging would extend.
Arlyn

Well yeah, it is true that (influence distance) is the primary of two
inherent questions in my querey, the other is the scale of the power of
the frame drag effect, i.e. if the above is true: how much faster
is/would be the observerved galactic spin than is the "real galactic
orbital speed" that is, from a space-time frame fixed reference that
subtracts the galactic core's frame drag quotient.

(ouch this stuff bends my head.. ;)

http://einstein.stanford.edu/
The Gravity Probe B mission is current and determining some of this
stuff, I was just wondering if we know the magnitudes well enough from
theory to eliminate the framework of my question.

Mike Williams

2004-11-28 07:41:51 UTC

Permalink

Post by Double-A
I don't know about the clustering, but the frame dragging influence
from a massive black hole might affect the galaxy such that the
galactic spin might appear to be faster than what gravity could
account for, if the rotation of the black hole were in the same
direction as the galactic rotation. And isn't this exactly what is
being observed?

What is being observed is that the rate of decrease of rotation speed as
you move out from the centre of the galaxy is less than one would expect
if most of the mass is concentrated at the core.

If ALL the mass were concentrated at the core, then the periods of stars
in the galaxy would obey the same rules as planets orbiting the Sun,
where the square of the period is proportional to the cube of the
radius. The mass of a galaxy isn't all concentrated at the core, and
this changes things so that the orbits in the outer regions are faster
than that. By observing how fast the outer orbits are compared to the
inner orbits we can determine that most of the mass of the galaxy is in
the galactic halo, where there are few stars and few obvious places for
that mass to reside.

I don't know much about frame dragging, but I suspect that it would tend
to affect the core regions far more than objects at the edge of the
galaxy. This might possibly fit what's going on if the black hole is
more massive than we would otherwise think, and rotates in the opposite
direction from the rest of the galaxy. Thus the speed of stars in the
halo would be mainly driven by gravity effects, but the speed of stars
near the core would be reduced. However, it seems very unlikely to me
that so many observed galaxies would happen to have counterrotating
black holes, since infalling stars would tend to spin up the black hole
so that it rotated in the same direction as the galaxy.

--
Mike Williams
Gentleman of Leisure

josephus

2010-03-06 19:46:57 UTC

Permalink

Post by Mike Williams

What is being observed is that the rate of decrease of rotation speed as
you move out from the centre of the galaxy is less than one would expect
if most of the mass is concentrated at the core.
If ALL the mass were concentrated at the core, then the periods of stars
in the galaxy would obey the same rules as planets orbiting the Sun,
where the square of the period is proportional to the cube of the
radius. The mass of a galaxy isn't all concentrated at the core, and
this changes things so that the orbits in the outer regions are faster
than that. By observing how fast the outer orbits are compared to the
inner orbits we can determine that most of the mass of the galaxy is in
the galactic halo, where there are few stars and few obvious places for
that mass to reside.
I don't know much about frame dragging, but I suspect that it would tend
to affect the core regions far more than objects at the edge of the
galaxy. This might possibly fit what's going on if the black hole is
more massive than we would otherwise think, and rotates in the opposite
direction from the rest of the galaxy. Thus the speed of stars in the
halo would be mainly driven by gravity effects, but the speed of stars
near the core would be reduced. However, it seems very unlikely to me
that so many observed galaxies would happen to have counterrotating
black holes, since infalling stars would tend to spin up the black hole
so that it rotated in the same direction as the galaxy.

there is a back of the envelope equation

1080/p where p = A(1-e^2)

it is related to the frame draggin near massive objects.

josephus

--
I go sailing in the summer
and look at stars in the winter
Its not what you know that gets you in trouble
Its what you know that aint so. -- Josh Billings

Double-A

2010-03-07 20:29:15 UTC

Permalink

Post by josephus

Post by Mike Williams

What is being observed is that the rate of decrease of rotation speed as
you move out from the centre of the galaxy is less than one would expect
if most of the mass is concentrated at the core.
If ALL the mass were concentrated at the core, then the periods of stars
in the galaxy would obey the same rules as planets orbiting the Sun,
where the square of the period is proportional to the cube of the
radius. The mass of a galaxy isn't all concentrated at the core, and
this changes things so that the orbits in the outer regions are faster
than that. By observing how fast the outer orbits are compared to the
inner orbits we can determine that most of the mass of the galaxy is in
the galactic halo, where there are few stars and few obvious places for
that mass to reside.
I don't know much about frame dragging, but I suspect that it would tend
to affect the core regions far more than objects at the edge of the
galaxy. This might possibly fit what's going on if the black hole is
more massive than we would otherwise think, and rotates in the opposite
direction from the rest of the galaxy. Thus the speed of stars in the
halo would be mainly driven by gravity effects, but the speed of stars
near the core would be reduced. However, it seems very unlikely to me
that so many observed galaxies would happen to have counterrotating
black holes, since infalling stars would tend to spin up the black hole
so that it rotated in the same direction as the galaxy.

there is a back of the envelope equation
1080/p where p = A(1-e^2)
it is related to the frame draggin near massive objects.
josephus
--
I go sailing in the summer
and look at stars in the winter
Its not what you know that gets you in trouble
Its what you know that aint so. -- Josh Billings

Wow! A thread revived from 2004! Can't do that with Google!

Double-A

Brad Guth

2010-03-07 22:23:36 UTC

Permalink

Post by josephus

Post by Mike Williams

What is being observed is that the rate of decrease of rotation speed as
you move out from the centre of the galaxy is less than one would expect
if most of the mass is concentrated at the core.
If ALL the mass were concentrated at the core, then the periods of stars
in the galaxy would obey the same rules as planets orbiting the Sun,
where the square of the period is proportional to the cube of the
radius. The mass of a galaxy isn't all concentrated at the core, and
this changes things so that the orbits in the outer regions are faster
than that. By observing how fast the outer orbits are compared to the
inner orbits we can determine that most of the mass of the galaxy is in
the galactic halo, where there are few stars and few obvious places for
that mass to reside.
I don't know much about frame dragging, but I suspect that it would tend
to affect the core regions far more than objects at the edge of the
galaxy. This might possibly fit what's going on if the black hole is
more massive than we would otherwise think, and rotates in the opposite
direction from the rest of the galaxy. Thus the speed of stars in the
halo would be mainly driven by gravity effects, but the speed of stars
near the core would be reduced. However, it seems very unlikely to me
that so many observed galaxies would happen to have counterrotating
black holes, since infalling stars would tend to spin up the black hole
so that it rotated in the same direction as the galaxy.

Wow! A thread revived from 2004! Can't do that with Google!
Double-A

Due to gravity and subsequent photon distortions, there's almost no
telling what we're looking at. It's like our universe is nothing but
a cosmic fun-house that's full of those distortion mirrors, false
dimensions and only the photon ghost(s) of whatever used to be.

BH gravity is simply affecting the surrounding dark matter by
continually expanding and compressing it, as well as subsequently
speeding and slowing photons, whereas gravity itself remains
instantaneous because the amount of mass within the universe has
supposedly never changed from the very get go. There now, once and
for all everything is resolved.

Save your money on this one, because we could easily outspend
trillions in our hard earned loot, and decades from now be no closer
if not further away from the truth.

btw, where the hell are those 70+ million year old seans when we need
them? (I forgot, they're all lost in space)

~ BG

Double-A

2004-11-27 20:50:04 UTC

Permalink

Post by Double-A

An interesting consideration.
I don't know about the clustering, but the frame dragging influence
from a massive black hole might affect the galaxy such that the
galactic spin might appear to be faster than what gravity could
account for, if the rotation of the black hole were in the same
direction as the galactic rotation. And isn't this exactly what is
being observed?
The only question would be how far the influence of the black hole's
frame dragging would extend.
Arlyn

Well yeah, it is true that (influence distance) is the primary of two
inherent questions in my querey, the other is the scale of the power
of
the frame drag effect, i.e. if the above is true: how much faster
is/would be the observerved galactic spin than is the "real galactic
orbital speed" that is, from a space-time frame fixed reference that
subtracts the galactic core's frame drag quotient.

(ouch this stuff bends my head.. ;)

http://einstein.stanford.edu/
The Gravity Probe B mission is current and determining some of this
stuff, I was just wondering if we know the magnitudes well enough from
theory to eliminate the framework of my question.

Double-A writes:

You should try posting your question to sci.physics.relativity.

There are several prominent astrophysicists who peruse that group, and
they may be able to give you a quantitative answer to your question.

Double-A