Tully-Fisher, fundamental plane - what about LSBs, dwarfs, etc?

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    Fundamental Plane
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Discussion Overview

The discussion revolves around the Tully-Fisher relationship and the Faber-Jackson relationship, particularly their applicability to various types of galaxies, including spirals, ellipticals, dwarfs, and low surface brightness (LSB) galaxies. Participants explore the implications of these relationships and question their universality and validity in different contexts.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants inquire about review articles discussing the applicability of the Tully-Fisher and Faber-Jackson relationships to all spirals and ellipticals.
  • Concerns are raised regarding the validity of general formulas, suggesting they imply universal properties of galaxies, such as baryon fraction and stellar density, which may depend on assumptions like a constant mass-to-light ratio.
  • One participant asserts that LSBs follow the Tully-Fisher relationship, citing it as a success for Modified Newtonian Dynamics (MOND).
  • Another participant speculates that there may be multiple Tully-Fisher relationships, similar to distinct populations of Cepheids, indicating complexity in the relationships among different galaxy types.
  • References to specific papers and authors are shared, including works by McGaugh and discussions on MOND and its implications for laboratory tests.
  • Some participants discuss the sensitivity required for laboratory tests of MOND and the challenges in observing deviations from established laws of gravity.
  • Speculation arises about the potential for laboratory experiments to detect MOND effects, with suggestions for redesigning experiments to focus on low acceleration scenarios.

Areas of Agreement / Disagreement

Participants express a range of views on the applicability of the Tully-Fisher relationship to different galaxy types, with some asserting that LSBs conform to it while others question the underlying assumptions. The discussion remains unresolved regarding the universality of these relationships and the implications for MOND.

Contextual Notes

Participants note limitations in the assumptions underlying the Tully-Fisher relation and the need for further exploration of the relationships among different galaxy types. There is also mention of unresolved mathematical steps and the dependence on specific definitions in the context of these relationships.

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In https://www.physicsforums.com/showthread.php?t=112890", Space Tiger mentioned the Tully-Fisher relationship for spirals, and the Faber-Jackson relationship, "part of the fundamental plane of elliptical galaxies".

Does anyone know of a review article on the extent to which these apply, to all spirals, all ellipticals, etc?

A related question: in terms of systematic properties, of any kind, do dwarfs, LSBs, or irregulars have relationships too? For example, do dwarf ellipticals and dwarf spirals 'obey' the same relationships as their normal (or giant) brethren? Are LSBs 'merely' faint spirals (that otherwise sit somewhere on the TFR)?
 
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I have no answer, but I wonder how such general formulas are valid at all. These relations seam to imply some surprising (to my eyes) universal properties of spiral or elliptical galaxies, such as the baryon fraction, the initial mass functions and the stellar density. These seam to be needed if the assumptions of a constant [itex]M/L[/itex] relation as well as surface brightness must hold. Both assumptions are needed to derive at least the Tully-Fisher relation.
 
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Yes, LSBs follow Tully-Fisher. This was a great triumph for MOND, which predicted it.
Best.
Jim
 
jgraber said:
Yes, LSBs follow Tully-Fisher. This was a great triumph for MOND, which predicted it.
Best.
Jim
Do you have some references?
 
hellfire said:
I have no answer, but I wonder how such general formulas are valid at all. These relations seam to imply some surprising (to my eyes) universal properties of spiral or elliptical galaxies, such as the baryon fraction, the initial mass functions and the stellar density. These seam to be needed if the assumptions of a constant [itex]M/L[/itex] relation as well as surface brightness must hold. Both assumptions are needed to derive at least the Tully-Fisher relation.
It's an intriguing question - is it some epiphenomenon, derivable from Newton/GR and the initial mass function of galaxy seeds and/or quasi-equilibrium collision/merger relationships? Or perhaps several different relationships/processes, which produce similar/overlapping results?

I've seen at least one paper which suggests that, not unlike Cepheids turned out to be two distinct populations, there is more than one TFR (frustratingly, I can't find it just now!).
 
Just try author MCGaugh on Arxiv Astro-ph. There are a bunch of references around 1998. Astro-ph/9801102 is one of the best. astro-ph/9711119 specifically discusses Tully-Fisher. McGaugh's MOND pages at UMd, www.astro.umd.edu/~ssm/mond/ are good, but they seem to be down right now.

Jim
 
Jim Graber,
did you look at this recent MOND paper by Magueijo and Bekenstein?

astro-ph/0602266

MOND habitats within the solar system
 
Yes, I have read that paper. I am very excited that they might see something with LISA pathfinder. I also like very much this paper http://arxiv.org/ftp/astro-ph/papers/0601/0601478.pdf
which is a good review of MOND which includes Tully- Fisher , Faber-Jackson, LSBs and Dwarf galaxies and also Globular clusters, which I think destroy CDM if the fine-tuning doesn't do it already, as I posted previously on Cosmic Variance. It lso ends with a suggestion that we could possibly see MOND effects in the laboratory. According to my calculation it would require Adelberger level sensitivity, but ranging over centimeters to meters and horizontal and then perhaps some kind of saddlepoint configuration as in the paper you referenced. on the other hand, one must not overlook negative results such as Iorio http://arxiv.org/PS_cache/gr-qc/pdf/0601/0601055.pdf
This paper references Pioneer Anomally but the same results apply to MOND if you overlook the absolute value restriction.
Best
Jim
 
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Hi Jim, feeling lazy tonight. What is Adelberger level sensitivity?
 
  • #10
Chronos said:
Hi Jim, feeling lazy tonight. What is Adelberger level sensitivity?
About 10^-11 cm/sec^2, see for example
http://www.npl.washington.edu/eotwash/pdf/prl63-2705.pdf
But this is differential acceleration not absolute acceleration.
Adelberger and most other lab workers are currently looking for a breakdown of the inverse square law at short distances, not long distances. They try to get the measured force stronger rather than weaker in most cases. The proposed lab tests of MOND would require precision measurements of very weak absolute forces at relatively long scales.

Jim
 
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I've not heard of any serious deviations, though the exact relationship one uses is band-dependent.
 
  • #12
SpaceTiger said:
I've not heard of any serious deviations, though the exact relationship one uses is band-dependent.
Yes, that is correct, no significant deviations from the inverse square law have been reported from lab experiments. And even most MOND proponents do *not* expect such a deviation to be observed. But in the paper referenced above, astro-ph/0601478, Scarpa has speculated that such a deviation would be seen. My back of the envelope estimates seem to tell me that lab experiments such as Adelberger's and others are sensitive enough, but would have to be redesigned to test this speculation. Most of the current lab experiments are looking for a deviation at the shortest possible distance due to extra dimensions or some other stringy effect. The MOND effect is a low acceleration, hence long distance effect. Hence the need to redesign the lab experiments to look "in a different place." I think the Scarpa speculation could be tested with a "long distance" of just a few centimeters, but this is just my speculation, based on Scarpa's and a few simple scaling argument calculations. A much more sophisticated "different place" argument, which also tests more mainstream MONDlike ideas is discussed in the paper Marcus referenced astro-ph/0602266.

Jim