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Thread: Spiral Galaxies: Stars move inwards with constant radial speed.

  1. #61
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    That was what the filament/streamers suggestion was about, but has been dropped due to lack of details. It was just a suggestion really, to show that if, for any reason, there was a region of increased density at the outer regions of the galaxy, - it would spiral in, increasing in density as it did so, and be a region where star formation was more likely.
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

  2. #62
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    Quote Originally Posted by Jean Tate View Post
    For avoidance of doubt, those four questions are not rhetorical; I look forward to your answers.
    The Q&A questions was not the full extent, there was an extensive search on the internet and arXiv, which came up with the three papers linked in post 31, which showed a substantial radial velocity both towards and away from the centre of the galaxy. Here is part of post 31 again.

    "There is some evidence here:
    https://arxiv.org/abs/0803.1826 Fig 6 page 38 and Table 5 pg 59, especially column Vavg

    and https://arxiv.org/abs/1805.00275 Fig 1 page 2 and Fig 10 page 7

    and https://arxiv.org/abs/1006.0064 Fig 4.2.1 page 45, which shows stars moving in highly elliptical orbits. These three papers show that there are stars in the bulge moving in highly eccentric orbits with one star measured with radial velocity of over 400 km/s."

    Currently looking into RAVE and awaiting Tusenfem's or the moderators response to private emails, or of post 55.
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

  3. #63
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    Quote Originally Posted by john hunter View Post
    The Q&A questions was not the full extent, there was an extensive search on the internet and arXiv, which came up with the three papers linked in post 31, which showed a substantial radial velocity both towards and away from the centre of the galaxy. Here is part of post 31 again.

    "There is some evidence here:
    https://arxiv.org/abs/0803.1826 Fig 6 page 38 and Table 5 pg 59, especially column Vavg

    and https://arxiv.org/abs/1805.00275 Fig 1 page 2 and Fig 10 page 7

    and https://arxiv.org/abs/1006.0064 Fig 4.2.1 page 45, which shows stars moving in highly elliptical orbits. These three papers show that there are stars in the bulge moving in highly eccentric orbits with one star measured with radial velocity of over 400 km/s."

    Currently looking into RAVE and awaiting Tusenfem's or the moderators response to private emails, or of post 55.
    Thank you.

    From your last sentence, I infer that you have not done your own, independent analyses of any relevant, publicly available astronomical data, but are considering doing so; is that correct?

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    I think that there are enough problems with the galactic disk and the stars moving radially and tangentially at the same speed, "spiralling" into the BH at the centre.
    So, I think we will let the "shooting out of the stars perpendicular to the disk" by a "change in how gravity works at high density" lie for the moment.
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  5. #65
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    Ok, thanks for the clarification.
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

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    Quote Originally Posted by john hunter View Post
    The Q&A questions was not the full extent, there was an extensive search on the internet and arXiv, which came up with the three papers linked in post 31, which showed a substantial radial velocity both towards and away from the centre of the galaxy. Here is part of post 31 again.

    "There is some evidence here:
    https://arxiv.org/abs/0803.1826 Fig 6 page 38 and Table 5 pg 59, especially column Vavg

    and https://arxiv.org/abs/1805.00275 Fig 1 page 2 and Fig 10 page 7

    and https://arxiv.org/abs/1006.0064 Fig 4.2.1 page 45, which shows stars moving in highly elliptical orbits. These three papers show that there are stars in the bulge moving in highly eccentric orbits with one star measured with radial velocity of over 400 km/s."

    Currently looking into RAVE and awaiting Tusenfem's or the moderators response to private emails, or of post 55.
    Thanks again.

    Two of those papers are, explicitly, about the “central parsec” of our own galaxy, and the third about the MW bulge, not the disk. None seem to have any relevance to the vast majority of stars in the disks of spiral galaxies.

    Do you have any observational data which is relevant to your ATM claims?

  7. #67
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    Quote Originally Posted by Jean Tate View Post
    Thanks again.

    Two of those papers are, explicitly, about the “central parsec” of our own galaxy, and the third about the MW bulge, not the disk. None seem to have any relevance to the vast majority of stars in the disks of spiral galaxies.

    Do you have any observational data which is relevant to your ATM claims?
    My bold. I'll second that.

    While I am at it, that graph in the second link in post 57 is not indicative of any discontinuity in the overall form of the galaxy. The author used different equations for different portions of the curve to empirically fit a smooth curve to an orbital velocity dataset without needing an ungodly huge number of terms. Remember, this is a multibody problem with no explicit analytical solution for the orbital elements. When the direction of the curvature changes several times it is my educated guess that a single equation for the whole range would have unacceptable squiggles between the fitted points. A set of cubic equations, each of which is used between two of the inflection (?) points, appears to be much more useful for the task at hand, which is interpolating between available data points.

  8. #68
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    Jean Tate and Hornblower. Post 31 Gave some evidence for a velocity dispersion in the bulge with a great many stars having velocity towards the CMO.

    Evidence for a universal flow of all stars in the disk towards the centre has not been found yet, although it's early days.

    However out of the billlions of stars that make a galaxy, the ATM thread requires approximately 1000 per year to enter the bulge from the disk. It could be that occasionally a star's orbit is changed by the spiral arms or other dense region causing a phenomenon of 'radial migration', which can occur both ways, inwards and outwards - it's going to take time to investigate whether there can be a net effect inwards - so maybe Jean Tate's advice of post 56 (of a pause) will be followed, if better evidence isn't found in a day or two.

    The theoretical advantages of the net inward flow are:
    A possible way for spiral patterns to emerge.
    A natural way to explain the matter distribution to give the flat rotation curves - i.e a constant inflow leads to a density rho proportional to 1/r^2 and m(r)/r=constant. Since most of the matter is dark matter, in the disk, the dark matter would also have a net inwards flow at constant speed.

    About the graph, second link post 57...Nature would have a way of smoothly linking the two straight lines in the previous graph. Only the points
    0 0
    1 8
    2 8
    3 8
    4 8 etc.. were put into the cubic-spline fitter, (try, from post 57 if you want), and a reasonable version of a rotation curve appeared. From this it strengthens the case that there are really just two regions. The flat one and the bulge of constant density, the rest of the shape seems to emerge as a requirement (according to the ATM model) of a constant inward flow meeting the constant density region.
    Last edited by john hunter; 2018-Jul-11 at 09:22 AM.
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  9. #69
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    Quote Originally Posted by john hunter View Post
    However out of the billlions of stars that make a galaxy, the ATM thread requires approximately 1000 per year to enter the bulge from the disk.
    IF03: Please give or cite your calculation that requires ~1000 stars per year to enter the bulge from the disk

    IF02: Please give your prediction from your ATM idea for the galactocentric radial velocity of bulge stars with a galactic longitude of around 0 ("directly inwards" from the Sun).

  10. #70
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    Quote Originally Posted by Reality Check View Post
    IF03: Please give or cite your calculation that requires ~1000 stars per year to enter the bulge from the disk
    There was something on this in post 19. However...

    vt^2/r=Gm(r)/r^2

    m(r)/r=vt^2/G

    m(r) =(vt^2/G)*r

    In this ATM model, there is an inwards flow of at vr. In one second a 'shell' of matter would move a distance vr, which is of similar magnitude to vt, say 'v' approx. 230 km/s

    The amount of matter passing a radius r in one second is all the matter between radii r+v to r.

    (v^2/G)*(r+v)-(v^2/G)*(r)= (v^2/G)*(v) = (v^3/G) or more exactly vt^2*vr/G

    For an estimate 230000^3/6.67*10^-11=1.8*10^26 kg/s = 5.8*10^33kg/year. The Sun has mass 2*10^30kg, so it's 2900 solar masses per year.

    A lot of this flow could be dark matter, but it must flow along the disk, then from disk to bulge, then to CMO, then be ejected (perhaps in bursts), but all at the same rate, on average, to maintain a stable equilibrium.
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

  11. #71
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    Quote Originally Posted by john hunter View Post
    Jean Tate and Hornblower. Post 31 Gave some evidence for a velocity dispersion in the bulge with a great many stars having velocity towards the CMO.
    Could you elaborate on this please?

    As I read the “bulge” paper, there is evidence for a lot of stars having a component of their velocity “towards the CMO”; would you please explain how you concluded, from that paper, that the velocity is radial?

    Also, doesn’t that paper also provide evidence for a lot of stars having a velocity component away from the CMO?

    Evidence for a universal flow of all stars in the disk towards the centre has not been found yet, although it's early days.

    <snip>
    In the absence of such evidence, what is the point of this ATM thread?

  12. #72
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    A thousand stars per year falling through a given radius does not sound like much until we multiply it by, say, 100 million years. Then it adds up to the entire population of the disk. Virtually all the stars would have to be moving this way, and as has been pointed out, the type of motion john hunter is envisioning would be readily observable by the same means that we observe the transverse motion with respect to the galactic center. I would say that describing this idea as stillborn is an understatement.

  13. #73
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    Quote Originally Posted by john hunter View Post
    There was something on this in post 19. However...
    If I put 'v' approx. 0 km/s, I get 0 solar masses per year. If I put v ~ c, I get an enormous number of solar masses per year. We are back to how can we trust a number that you have presented no evidence for?

    vt^2/r=Gm(r)/r^2 is merely the mean orbital speed of a object in an essentially circular orbit around a mass of m(r). The shell theorem tells me that I can replace m(r) with m. In both cases, the radial velocity is zero. That implies that your ATM idea includes that Newtonian gravity is wrong. But that equation is derived from Newtonian gravity!
    Last edited by Reality Check; 2018-Jul-11 at 11:50 PM.

  14. #74
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    Reality Check: The tangential velocity component lets us estimate m(r)/r, which is v^2/G, but there can be a radial component too. If this is of similar magnitude to v (not 0 or c) then in-falling matter can trace out a spiral pattern...

    and Hornblower: The value of the radial component may vary from galaxy to galaxy, a great deal of matter would be passing through the centre and out again, but not necessarily destroyed, for the milky way it would take about 10^42kg divided by 10^26kg/s = 10^16s approx. 300 million years (This doesn't mean that the galaxy would disappear. Matter would be ejected from the CMO mostly perpendicular to the disc and some return mainly at the edges). If the radial component is on average 10% of the tangential, then it would be 10 times longer.

    Jean: The point of the first link in post 31 (https://arxiv.org/abs/0803.1826 Fig 6 page 38 and Table 5 pg 59, especially column Vavg), was to show that a substantial radial component exists in the bulge, previously to that (in the Q&A thread) there was no evidence found for any substantial radial component. Many stars have 200km/s for their radial component, similar to the tangential. there was also a 400km/s (radial).

    So instead of neat circular orbits, there are highly elliptical orbits - a chaotic situation.

    If their orbit was too close - they could be absorbed by the CMO. Also they could disturb each others orbits, which could occasionally cause one in an elliptical orbit to be diverted too close to the CMO and absorbed. Imagine there were 2000 stars in such orbits and gradually one by one they are absorbed by the CMO - later there might be 1000 in orbit and 1000 now forming part of the CMO. That's a net in-fall.

    As for 'universal flow' that's true. Not every star is always moving towards the centre (in this ATM thread). It's an average, net, in-fall. Averaged in terms of number of stars and also in time. You mentioned that you would like to see evidence for radial motion in the disc. There will be something posted on that soon.
    Last edited by john hunter; 2018-Jul-12 at 10:12 PM.
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    Quote Originally Posted by john hunter View Post
    Reality Check: The tangential velocity component lets us estimate m(r)/r, which is v^2/G, but there can be a radial component too....
    Yes: the tangential velocity component at r gives the mass inside r. But, the only radial component "estimate" you can make is that the radial component is between 0 and c. More realistically, guess that it is within an order of magnitude (or 2?) of the tangential velocity. Or look at the velocities of as many stars as possible in the galaxy and use that distribution. Or find values in the literature. Or find sources that give methods of deriving it from data such as the radial velocity (solar not galactic).

    It is still irrelevant that stars spiral in.
    Last edited by Reality Check; 2018-Jul-13 at 02:40 AM.

  16. #76
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    Here is probably the most up to date and best data available, for radial motion in the disc of the Milky Way, https://arxiv.org/abs/1804.09380 .
    What it shows is a complex situation, in which there are significant radial velocities both inwards and outwards. The paper has a lot of detail in it, but here are some relevant parts.

    -------------------------------------------------------------------------

    In the Abstract, just under Results: “The maps show the complexity and richness of the velocity field of the galactic disc. We observe streaming motions in all the components of the velocities…”

    Figure 10 page 11, top left diagram, shows VR, an interesting diagram which shows a vast blue region to the right of the sun (further radially outwards) moving inwards to the centre of the galaxy, at 15km/s (VR is the galactocentric radial velocity as described in the footnote at the bottom of page 4). Further radially inwards, the red region, there is a vast region moving radially outwards.

    Figure 12 page 13 shows median radial velocity against radius.
    To quote section 3.2. page 10
    “The median radial velocity has a U-shape, with a minimum at about 9 kpc. Around this minimum and within a broad layer below and above the mid-plane, the median radial velocity is negative, meaning that more stars move inwards than outwards. At a distance from the minimum of 1 to 2 kpc, the median radial velocity becomes positive, meaning that more stars move outwards than inwards.“ The data is probably more reliable at smaller distances from the sun, where the results show an inward flow.

    -----------------

    Top of page 16 “Grand et al. (2016) used cosmological simulations to study the large-scale motions induced by the spiral arms in a Milky Way-like galaxy. The simulation shows radially outwards and azimuthally backwards motions on the trailing edge of the arms, while on the leading edge, the effect is reversed: the streaming motion is oriented inwards and forwards.

    There are also Fig 19, page 16 and Figs C1, C2 pages 29/30.
    ----------------

    The dispersion is large for VR, a larger dispersion than for the other velocity components. Up to 70km/s for sigma(VR), Fig 16 page 15. And Figs C8/9 pages 36 and 37

    In Conclusions page 21
    "The picture of the Milky Way disc kinematics drawn by Gaia DR2 is both rich and complex. Streaming motions are observed in all three velocity components…We find that stars clearly appear to be organised in kinematic arches… Gaia DR2 is now available to the astronomical community… We can expect this great wealth of information to trigger an intense activity in the galactic community in the years to come."

    ---------------------------------------------------------------

    It’s probably not going to be possible to quickly find conclusive evidence for or against a net radial inwards motion, but the paper shows that such a net inwards motion is a serious possibility, especially given that vast quantities of matter are periodically ejected, from galaxies, perpendicular to the disc.
    Last edited by john hunter; 2018-Jul-13 at 10:05 AM.
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  17. #77
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    I see nothing in the paper linked in post 76 from which I would infer a long term, systematic spiraling in of stars into the center of the galaxy. The authors note that the galaxy in not in equilibrium, which is normal after recent mergers with various small galaxies. For disk stars I would expect a present day net inflow, if any, to evolve into a net outflow as the respective stars round the periapsides of their eccentric orbits and start moving out again. Stars that remain intact in extremely close approaches to the central black hole will just whip around and go back out in the same orbit, like an Oort cloud comet flying by the Sun. The stuff that squirts out along the polar axis is gas that came into the accretion disk and was deflected by fluid dynamics that would not apply to intact stars.

    This ATMer appears to be cherry-picking words and phrased from published papers upon envisioning them as somehow concurring with his ATM idea.

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    H
    Last edited by Dave Lee; 2018-Jul-13 at 03:45 PM. Reason: error

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    Hello John

    Your key message is valid.
    However, did you also consider an option for stars to drift outwards instead of inwards?
    Last edited by Dave Lee; 2018-Jul-13 at 04:54 PM.

  20. #80
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    Quote Originally Posted by john hunter View Post
    <snip>

    It’s probably not going to be possible to quickly find conclusive evidence for or against a net radial inwards motion, but the paper shows that such a net inwards motion is a serious possibility,
    I think you and I must be reading different papers (YMMV of course). I cannot see how such a thing is a “serious” possibility.

    especially given that vast quantities of matter are periodically ejected, from galaxies, perpendicular to the disc.
    Huh?

    Do you have solid evidence for this? Perhaps start with quantifying “vast quantities”, and “galaxies”. Thanks in advance.

  21. #81
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    Quote Originally Posted by john hunter View Post
    Here is probably the most up to date and best data available, for radial motion in the disc of the Milky Way, https://arxiv.org/abs/1804.09380 ...
    The real question is:
    IF04: How closely do the galactocentric velocities in this paper match your ATM idea predictions, john hunter?

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    A few weeks ago, evidence was being wondered about for any radial motion at all, either in the bulge or disc of a galaxy.

    In post 31 evidence was given for substantial radial motion in the Milky Way bulge.
    The paper in post 76 shows that there are regions with substantial radial motions of matter in the Milky Way disc.

    The situation is complex and chaotic with streaming motions of matter both inwards towards and outwards from the galactic centre.
    A model with near circular orbits would not match these observations. A model with a substantial radial inflow could.

    Nasa’s Fermi telescope found these ‘Fermi bubbles’. Immense Lobes seemingly formed by matter ejected perpendicular to the Milky Way disc. https://www.nasa.gov/mission_pages/G...structure.html

    This paper https://arxiv.org/abs/1612.01578
    puts the visible mass of the bubbles in excess of 2x10^6 solar masses, with a minimum outflow rate of 0.2 solar masses per year. There is 20 times more dark matter in the disc than visible, and the paper used a low ejection speed of 1000km/s. Jets commonly occur in galaxies with velocities near the speed of light. Streaming radial motion outwards in the disc has also been found (link in post 76) , so there are a few reasons to think that this minimum is set low and will be increased as our knowledge/observations improve.

    There is evidence of substantial outflows in the form of Jets and AGNs from other galaxies too, will be posted later.
    Last edited by john hunter; 2018-Jul-16 at 11:36 AM.
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  23. #83
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    Quote Originally Posted by john hunter View Post
    A few weeks ago, evidence was being wondered about for any radial motion at all, either in the bulge or disc of a galaxy. ...
    We were worried about there being any measured galactocentric radial velocity as needed by your ATM idea. That is still the case.

    It is obvious to people who think about orbits of stars in that galaxy that there will be some, probably random galactocentric radial velocities. No radial velocities for an orbit around a static mass. Add the changes in distribution of masses as a star orbits and it will move outward and inward during its orbit. Thus some, probably random galactocentric radial velocities.

    Your ATM idea is that stars have constant galactocentric radial velocities, either inward or outward so violating Newtonian gravity.

    Imagining that any measured radial velocities at all support your ATM idea is not science. Thus
    IF04: How closely do the galactocentric velocities in this paper match your ATM idea predictions, john hunter?

    Promising to derail into irrelevant jets and AGNs is not good. Your ATM idea is not about supermassive black holes ejecting gas from their accretion discs. Stick with the Milky Way where we have actual measurements of billons of stars.

  24. #84
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    Quote Originally Posted by john hunter View Post
    Nasa’s Fermi telescope found these ‘Fermi bubbles’. Immense Lobes seemingly formed by matter ejected perpendicular to the Milky Way disc. https://www.nasa.gov/mission_pages/G...structure.html
    That is irrelevant. NASA's Fermi Telescope Finds Giant Structure in our Galaxy (Nov. 10, 2010)
    Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure's shape and emissions suggest it was formed as a result of a large and relatively rapid energy release - the source of which remains a mystery.

    One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way's black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's center several million years ago
    A past galactic jet may have created this structure. This article is almost 8 years old. There may be a more supported cause.

    Also irrelevant is a study of the flows in the Northern Fermi Bubble: Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi Bubble

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    Quote Originally Posted by Jean Tate View Post
    Do you have solid evidence for this? ...[that galaxies periodically eject vast quantities of matter perpendicular to the disk]...Perhaps start with quantifying “vast quantities”, and “galaxies”. Thanks in advance.
    Although it's a quasar here is an example of a mass outflow of 500-1000 solar masses per year…… https://arxiv.org/abs/1503.01481
    ---
    From Ned Wright about Spiral galaxies https://ned.ipac.caltech.edu/level5/Irwin/Irwin4.html
    Near the start of section 4.3
    “the evidence for outflows from galaxies, especially nuclear outflows, is abundant, not because the fraction of galaxies displaying nuclear outflows is large but because, observationally, such outflows can be spectacular”

    And near the end of section 4.3 “a recent survey by Sorathia and Irwin (1995) of 16 radio-selected edge-on galaxies suggests that almost every galaxy shows some radio emission extending beyond the optical disk. If significant numbers of star forming galaxies are evaporating at rates of order 1 [solar mass] yr-1 as suggested for galaxies like the Milky Way (Völk 1991), or higher for starburst galaxies, then substantial depletion of the galaxy's ISM and enrichment of the IGM may occur”
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

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    Quote Originally Posted by Reality Check View Post
    It is obvious to people who think about orbits of stars in that galaxy that there will be some, probably random galactocentric radial velocities....Your ATM idea is that stars have constant galactocentric radial velocities...
    Promising to derail into irrelevant jets and AGNs is not good.
    Yes, and it should also be obvious that the ATM thread didn't mean that every star always has to have a constant inward radial speed.
    On average, over the number of stars and over time, there will be a constant (with time and radius, for the flat region of the curve) inwards radial speed vr = f*vt where f is a fraction, perhaps of order unity for some galaxies, lower for others.

    It seems from the paper in post 76 that some stars may move in streams, so within the same galaxy perhaps there are stars with f=1 and stars with a lower f value. On average a constant inwards 'flow' with an fav is maintained, giving the constant m(r)/r ratio, leading to the constant vr rotation curves.

    The main point being that there is much more inflow than thought by the mainstream - and that it is constant for all r (on average).
    So the outflow perpendicular to the disk is important, and was asked about by Jean Tate. Actually total outflow = total inflow, so the above refers to "in the disk". The outflow being mainly, but not totally, perpendicular to the disc.

    There is a reason that the inflow is constant with radius, which might be discussed if the previously eluded to ATM thread of 2005 is included later.
    Last edited by john hunter; 2018-Jul-16 at 10:46 PM.
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  27. #87
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    Quote Originally Posted by john hunter View Post
    Yes, and it should also be obvious that the ATM thread didn't mean that every star always has to have a constant inward radial speed.
    It should be obvious that I am using the same meaning of "constant as in the thread title of "Spiral Galaxies: Stars move inwards with constant radial speed.".
    Quote Originally Posted by Reality Check View Post
    It is obvious to people who think about orbits of stars in that galaxy that there will be some, probably random galactocentric radial velocities. No radial velocities for an orbit around a static mass. Add the changes in distribution of masses as a star orbits and it will move outward and inward during its orbit. Thus some, probably random galactocentric radial velocities.

    Your ATM idea is that stars have constant galactocentric radial velocities, either inward or outward so violating Newtonian gravity.
    Newtonian gravity tells us that stars will orbit with random perturbations in and out, averaging out to zero. If you want to change your ATM idea to not violate Newtonian gravity then remove any mention of stars falling into or being ejected from the galaxy center.
    Last edited by Reality Check; 2018-Jul-16 at 11:49 PM.

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    Quote Originally Posted by john hunter View Post
    A few weeks ago, evidence was being wondered about for any radial motion at all, either in the bulge or disc of a galaxy.

    In post 31 evidence was given for substantial radial motion in the Milky Way bulge.
    The paper in post 76 shows that there are regions with substantial radial motions of matter in the Milky Way disc.
    I think you are continuing to confuse a substantial radial component of motion with radial motion. If you wish to continue with this ATM idea, I will try to sharpen up my questions and critiques on this point.

    The situation is complex and chaotic with streaming motions of matter both inwards towards and outwards from the galactic centre.
    A model with near circular orbits would not match these observations. A model with a substantial radial inflow could.
    And yet you have presented no evidence (that I have seen) on the latter point, other than bald statements.

    Nasa’s Fermi telescope found these ‘Fermi bubbles’. Immense Lobes seemingly formed by matter ejected perpendicular to the Milky Way disc. https://www.nasa.gov/mission_pages/G...structure.html

    This paper https://arxiv.org/abs/1612.01578
    puts the visible mass of the bubbles in excess of 2x10^6 solar masses, with a minimum outflow rate of 0.2 solar masses per year.
    How much of that is in the form of stars? And what does it have to do with this ATM idea?

    There is 20 times more dark matter in the disc than visible, and the paper used a low ejection speed of 1000km/s. Jets commonly occur in galaxies with velocities near the speed of light. Streaming radial motion outwards in the disc has also been found (link in post 76) , so there are a few reasons to think that this minimum is set low and will be increased as our knowledge/observations improve.

    There is evidence of substantial outflows in the form of Jets and AGNs from other galaxies too, will be posted later.
    john hunter, you seem to be unaware of the enormous amount of work that has been done on aspects which would seem pretty central to your ATM idea. For example, there's been a lot of work done on how/whether bars in spiral galaxy "funnel" matter into the bulge/nucleus, on the extent to which the observed morphological features of spirals and lenticulars are due to secular evolution vs minor vs major mergers, on how the bulges of spiral galaxies have evolved (and whether that evolution is different for so-called pseudo-bulges vs "true" bulges), etc, etc, etc.

    I think in an earlier post there was a comment to the effect that you seem to be doing an awful lot of cherry picking, and not undertaking the necessary literature searches to understand at least the context of your ATM ideas.

  29. #89
    Join Date
    Feb 2010
    Posts
    544
    Quote Originally Posted by john hunter View Post
    Although it's a quasar here is an example of a mass outflow of 500-1000 solar masses per year…… https://arxiv.org/abs/1503.01481
    ---
    From Ned Wright about Spiral galaxies https://ned.ipac.caltech.edu/level5/Irwin/Irwin4.html
    Near the start of section 4.3
    “the evidence for outflows from galaxies, especially nuclear outflows, is abundant, not because the fraction of galaxies displaying nuclear outflows is large but because, observationally, such outflows can be spectacular”

    And near the end of section 4.3 “a recent survey by Sorathia and Irwin (1995) of 16 radio-selected edge-on galaxies suggests that almost every galaxy shows some radio emission extending beyond the optical disk. If significant numbers of star forming galaxies are evaporating at rates of order 1 [solar mass] yr-1 as suggested for galaxies like the Milky Way (Völk 1991), or higher for starburst galaxies, then substantial depletion of the galaxy's ISM and enrichment of the IGM may occur”
    OK, full disclosure: I have been actively hunting SDRAGNs (spiral galaxies with double (radio) lobe AGNs) for some time now, based primarily on Radio Galaxy Zoo. I lead a team working on finding and confirming them. In the literature, there are ~a dozen, and we have found perhaps another dozen (publication pending, as they say). Out of perhaps a million confirmed spirals.

    I have also been active in Galaxy Zoo for several more years, and have been involved (though not as centrally as with SDRAGNs) in the now many studies of voorperjies, or EELRs (extended emission line regions), which are found predominantly associated with spiral and lenticular galaxies with dormant or active AGNs (many are "disturbed", indicating past or ongoing mergers, or other recent perturbations).

    From this work, I can say with a very high degree of confidence that what you present is pure cherry picking.

    I strongly recommend that you request a pause, and spend a not inconsiderable amount of time doing appropriate (not cherry-picking) literature searches. If, after that, you feel you have a good ATM case to make, then request that this thread be re-opened.

    Should you choose to not take my suggestion, I may post some details of the work that has been done, work that is directly relevant to your idea, and which you seem to be unaware of (or have chosen to ignore).

  30. #90
    Join Date
    Nov 2005
    Posts
    533
    Quote Originally Posted by Reality Check View Post
    If you want to change your ATM idea to not violate Newtonian gravity then remove any mention of stars falling into or being ejected from the galaxy center.
    It is you that is claiming that Newtonian gravity is violated in the orbits. In posts 12 and 39, it was mentioned that a loss in angular momentum of visible matter might be transferred to the dark matter, in the disc. The inflow in the bulge was described in post 74, not violating Newtons laws. So the inflow part of the ATM proposal, and the ejections will remain.

    Taking Hornblower's comments on board, the only changes might be to the fraction fAV described in post 86, which might be as low as 1% for some galaxies, and whether stars can remain intact or not (which needs time to look into).
    Imagine water flowing down a plughole, the vr can be greater than the vt but the inflow is occurring.
    Last edited by john hunter; 2018-Jul-17 at 12:27 PM.
    "...when you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

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