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Single vs Double hot spots for BH Jets? (e.g. Pictor A)



 
 
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  #11  
Old March 1st 17, 10:42 PM posted to sci.astro.research
[email protected]
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Posts: 35
Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

I should mention, regarding the rain idea I'm studying, that if matter is s=
hot out of a galaxy along the axis of rotation by BH jet activity, and it s=
ubsequenty "rain's" back down onto the galaxy, the NET angular momentum of=
the "rain" would also be zero. It would also be orthogonal to (have angul=
ar momentum vector orthogonal to) the angular momentum of the galaxy.

Thus, rain if it exists, will reduce net angular momentum of a galaxy, shut=
ting down rotation and evolving the galaxy from spiral forms toward EO.

This is possible if the individual particles, stars, gas, dust, rain back d=
own along highly elliptical geometries with long axis coincident with galac=
tic rotation vector, AND, the rain is random with regards to which side of =
the central black hole it falls on. This way, the momentum vectors for eac=
h "particle" are roughly within the disk of the galaxy's rotation, ~normal =
to it's angular rotation vector. But the vector for each particle is diffe=
rent so that there is no net rotation axis.

In a sense, the rain would probably be a bit like a faint bar of stuff that=
thermalization would randomize......the rain would become random like orbi=
ts in a GC, and, the matter of the galaxy with which the interaction took p=
lace would also become more random, more like an elliptical.

So, BH jets, are observed to eject matter. **IF** that matter rains back d=
own, then it should act to evolve the galaxy toward elliptical by some degr=
ee. More rain, more evolution.

Question is, can any observation detect such a rain IF it exists? We see f=
aint extensions. But finding their velocity is harder still and I don't kn=
ow of any observation for the velocity of the faint extended material along=
BH jet axis'.

This mechanism is why the EO to Bar evolution path makes no sense to me. T=
here are only old stars in ellipticals. Barred spirals have newborn stars.=
And most galaxies observed are ellipticals, and they have only old stars.=
EO ought to be the end game it seems to me.

Is it the general expectation that all elliptical galaxies will evolve to b=
arred spirals eventually?

rt

  #12  
Old March 1st 17, 10:43 PM posted to sci.astro.research
Martin Brown
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Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

On 26/02/2017 04:43, wrote:
On Thursday, February 23, 2017 at 7:47:09 AM UTC-8, Martin Brown
The general theory is that as galaxies age they mature towards having a
barred spiral structure through perturbations of the stellar orbits in
the galactic gravitational potential. See for example:

https://www.nasa.gov/mission_pages/h..._galaxies.html
http://hubblesite.org/hubble_discove..._evolution.pdf

The same happens in numerical simulations of stars in galaxies.


Nice images, some of my favorite galaxies.

The sequence for bar evolution seems backwards to me (counter to
entropy which wants to randomize things....globular clusters and
ellipticals seem to me to be the end stage of evolution).


Entropy doesn't mean what you think it means.

When a galaxy is formed the original conditions determine how much total
angular momentum it inherits from the gas cloud that it formed from. The
ratio of mass to angular momentum influences what it looks like and at a
certain amount of angular momentum spontaneous symmetry breaking occurs
and the whole thing looks much more complicated.

Q Is it known at what ratio of mass to angular momentum a forming galaxy
necessarily becomes a spiral rather than elliptical?

Here is one paper I found which tries to address the problem
semianalytically. I found another but lost the link. Perhaps someone can
suggest a better review of the morphology and secular of galaxies in
relation to their instrinsic angular momentum.

https://arxiv.org/pdf/1605.00647.pdf

The formation of a bar also seems counter to Rubin observation that
the circular velocity is constant with radius.......the larger
circular orbit would inevitably sweep the arms into a spiral.


ISTR that in the early days of large scale galactic simulations they had
to work very hard to prevent bars from falling. I suspect bars and
ellipticals represent a galactic manifestation of Ovenden's conjecture
that stellar systems evolve towards configurations where the stars keep
their distance from each other as far is possible.

This is more the sequence that I'm studying / seeking evidence for:



1) Mice https://en.wikipedia.org/wiki/Mice_G...Telescope).jpg

2) Fornax https://en.wikipedia.org/wiki/Barred...a-99-hires.jpg


3) ngc1097 https://en.wikipedia.org/wiki/NGC_1097

4) ngc1232 https://en.wikipedia.org/wiki/NGC_12...e:NGC1232B.jpg

This is about opposite the sequence at the Hubblesite link you sent.

Basics:

The net angular momentum of a globular cluster of stars is zero,
right?


Certainly small angular momentum.

And slowly getting smaller by expelling the odd star to infinity and the
remainder becoming ever more tightly gravitationally bound.

Same for an elliptical (generally and ignoring the possible small
rotation component some have).

In contrast, spirals have large angular momentum in their outer
disk stars, vs (much? near zero) smaller angular momentum in their
central bulges of stars.


That is because angular momentum scales as Mr^2

As suggested, To merge a counter rotating galaxy is a way to zero
out the angular momentum. That's not what I'm suggesting.


But that is the only thing that will work (or a galaxy with same spin
whose orbit is retrograde to the first and with goldilocks conditions to
null out the total angular momentum). Angular momentum is a *vector*
quantity you have to add an equal and opposite amount to null it out.

If you instead add angular momentum that is orthogonal, then you
randomize the stellar orbits. This is what we see in ellipticals
and globulars.

Nonsense. If you added an orthogonal amount of angular momentum to
original galaxy one with W1 = (I, 0, 0) and add W2 = (0, I, 0)

You get a new merged galaxy with WTot = (I, I, 0)

In other words sqrt(2).I and at 45 degrees to the original spin axis.

The angular momentum of matter raining down along an approximately
axial line (ie, in a highly elliptical orbital geometry, with the
long axis of the ellipse being the rotation axis of the galaxy.
Then, the axis of rotation for the galaxy is orthogonal to the axis
of rotation for the ellipse of in falling material.


You really do not understand the basics of Newtonian dynamics.

As this "rain" component becomes "thermalized" by interacting with
the mass of the galaxy, some of the disk stars orbits are transformed
into elliptical orbits. In this way, a spiral galaxy could evolve
to become an elliptical galaxy.


Angular moment is one of the key invariants that is conserved in an
isolated system - and that remains true even in the full GR treatment.

And it all began from the BH that ejected matter along the axis of
too much angular momentum. Each episode of activity, increasing
the size of the bulge, until eventually the galaxy is an elliptical
and the stars can age from there............(ellipticals have older
stars)


It doesn't work like that.

You would have to drop serious amounts of matter in a retrograde
orbit


Serious amounts of matter............yes


But the angular momentum would remain the *same* the galaxy might spin
more slowly as it became more massive since the same angular momentum
would be shared by a larger total mass

retrograde orbit.............no.

It needs to cancel out or randomize, the existing angular momentum.
See above.


Sorry but you do not have a clue.

--
Regards,
Martin Brown

  #13  
Old March 5th 17, 08:46 AM posted to sci.astro.research
Steve Willner
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Posts: 1,172
Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

In article ,
writes:
Is it the general expectation that all elliptical galaxies will
evolve to barred spirals eventually?


No. Most, maybe all, galaxies evolve to ellipticals. There is great
debate about the mechanism and the timing of this evolution, but
observations show greater fractions of ellipticals at later cosmic
times. One paper I happen to be familiar with is at
http://adsabs.harvard.edu/abs/2015ApJ...803...26P

I especially like Figs 12 and 13 (and had nothing at all to do with
making them other than helping provide some of the data).

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
  #14  
Old March 13th 17, 05:40 AM posted to sci.astro.research
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Posts: n/a
Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

On Wednesday, March 1, 2017 at 1:43:29 PM UTC-8, Martin Brown wrote:
On 26/02/2017 04:43, ross wrote:
On Thursday, February 23, 2017 at 7:47:09 AM UTC-8, Martin Brown


If you instead add angular momentum that is orthogonal, then you
randomize the stellar orbits. This is what we see in ellipticals
and globulars.

Nonsense. If you added an orthogonal amount of angular momentum to=20
original galaxy one with W1 = (I, 0, 0) and add W2 = (0, I, 0)

You get a new merged galaxy with WTot = (I, I, 0)

In other words sqrt(2).I and at 45 degrees to the original spin axis.

Regards,
Martin Brown


OK, fine, yes I understand and see that result. But you are
considering just one infalling object and it's single interaction
with a single entity of the original galaxy.

Suppose I have a spiral galaxy, disk with central bulge. We can
find the net angular momentum.

Now, thought experiment, I take a bunch of mass, call it a bunch
of stars and I place them far above the spiral galaxy, say 100,000
to 200,000 light years from the black hole, in a clump along the
axis of rotation of the spiral galaxy. Then, I allow all of these
stars to rain down onto the spiral galaxy. They fall on random
sides of the black hole, and have random elliptical motions with a
very large eccentricity..........long axis parallel to the spiral
axis of rotation.

Suppose the total mass of this infalling material is significant
in comparison to, but smaller than, the mass of the spiral galaxy.

For each in falling thought experiment star, that interacts with a
star of the spiral, the net angular momentum will become as you
say, at a 45 degree angle. =20

HOWEVER, some of the in falling stars have a 45 degree angle one
way, and others have a 45 degree angle in another orientation. And,
as the falling stars manage to fall all around the black hole like
rain drops, the net angular momentum for each of these infalling
stars is in a different direction. Further, some are falling from
North pole down onto the galaxy, others are falling from the South
pole up into the galaxy, further increasing the random nature of
the resultant stellar motions.

Take those, and then secondary and tertiary further interactions
with the spiral galaxy stars, and the total motions become randomized
and the galactic net angular momentum will be reduced..........right?

Now I don't know that it is known what the faint extensions of
active galaxies are (gas, dust, stars, ????.........e.g. David
Malin's unsharp masking method for bringing out faint details for
these objects, showing extensions coincident with radio jet directions
for several active galaxies....

So I don't know that the extensions are stars (does anyone?)

But no matter what, if the total mass is significant and if that
mass rains back down, it still seems to me that it should reduce
the net angular momentum of the spiral.

rt
  #15  
Old March 16th 17, 09:36 AM posted to sci.astro.research
Martin Brown[_3_]
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Posts: 189
Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

On 13/03/2017 04:40, wrote:
On Wednesday, March 1, 2017 at 1:43:29 PM UTC-8, Martin Brown wrote:
On 26/02/2017 04:43, ross wrote:
On Thursday, February 23, 2017 at 7:47:09 AM UTC-8, Martin Brown


If you instead add angular momentum that is orthogonal, then you
randomize the stellar orbits. This is what we see in ellipticals
and globulars.

Nonsense. If you added an orthogonal amount of angular momentum to
original galaxy one with W1 = (I, 0, 0) and add W2 = (0, I, 0)

You get a new merged galaxy with WTot = (I, I, 0)

In other words sqrt(2).I and at 45 degrees to the original spin axis.


OK, fine, yes I understand and see that result. But you are
considering just one infalling object and it's single interaction
with a single entity of the original galaxy.


It works just the same for many infalling objects too. Angular momentum
is conserved in an isolated dynamical system if there is no friction.

Suppose I have a spiral galaxy, disk with central bulge. We can
find the net angular momentum.

Now, thought experiment, I take a bunch of mass, call it a bunch
of stars and I place them far above the spiral galaxy, say 100,000
to 200,000 light years from the black hole, in a clump along the
axis of rotation of the spiral galaxy. Then, I allow all of these
stars to rain down onto the spiral galaxy. They fall on random
sides of the black hole, and have random elliptical motions with a
very large eccentricity..........long axis parallel to the spiral
axis of rotation.

Suppose the total mass of this infalling material is significant
in comparison to, but smaller than, the mass of the spiral galaxy.


OK. Simple example to try and make the distinction between angular
momentum and angular velocity. Lets say we have a slab of material with
zero angular momentum that we somehow stitch onto the original galaxy
instantly and that they have the same mass M1 = M2 = M.

W1 = (I, 0, 0) and W2 = (0, 0, 0) Wtot = W1= (I, 0, 0) Mtot = 2M

The angular velocity has been halved by this process since the new
galaxy has the same angular momentum as before but is now mass 2M.

But no matter what, if the total mass is significant and if that
mass rains back down, it still seems to me that it should reduce
the net angular momentum of the spiral.


Only because you don't understand basic Newtonian physics.

--
Regards,
Martin Brown

  #16  
Old March 19th 17, 09:31 AM posted to sci.astro.research
[email protected]
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Posts: 35
Default Single vs Double hot spots for BH Jets? (e.g. Pictor A)

OK, decades since I've crunched some of these equations, so thanks for
the refresher.

How about this example:

at (0,0,0) I have a SMBH at the center of a galaxy.

The galaxy is purely a disk of stars in the XY plane, with rotation
about the Z axis. Right hand rule, thumb North, fingers show stellar
rotation direction. Disk is thin, call it 1pc compared to 50kpc radius
for the disk.

Now, I drop a bunch of stars from N and S of the SMBH. They fall onto
different sides of the SMBH, AND, they thermalize with the disk stars.

Seems to me I will form a central bulge where initially none existed.

From your comments (which make sense), the net angular momentum of the
system will not change. But where I'm still confused, is how the sum of
angular momentum of the in falling material, adds to the disk rotation
angular momentum.

for the disk material, the angular momentum vector is in the north Z
direction. For the infalling material, the angular momentum vector for
each in falling star is in the XY plane, orthogonal to the disk
material.

As the infalling material "thermalizes" with the disk stars, a central
bulge will form with random motions..........but I am not sure how the
Net becomes changed or if it does.

If the infalling material falls in equally on all sides of the central
SMBH, then, it must have zero angular momentum. Therefore by your
comments, (which make sense) the resultant bulge must have a net angular
momentum that's still along the Z axis north.

right?

rt

 




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