2011A&A...532A.121H


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST08:22:06

2011A&A...532A.121H - Astronomy and Astrophysics, volume 532A, 121-121 (2011/8-1)

The Bosma effect revisited. I. HI and stellar disc scaling models.

HESSMAN F.V. and ZIEBART M.

Abstract (from CDS):

The observed proportionality between the centripetal contribution of the dynamically insignificant HI gas in the discs of spiral galaxies and the dominant contribution of dark matter (DM) - the ``Bosma effect'' - has been repeatedly mentioned in the literature but largely ignored. Since this phenomenology, if statistically significant, tells us something about the relationship between the visible baryonic and invisible DM, it is important to re-examine the reality of this effect using formal tests and more modern data. We have re-examined the evidence for the Bosma effect, either by scaling the contribution of the HI gas alone or by using both the observed stellar disc and HI gas as proxies. We have calculated Bosma effect models for 17 galaxies in The HI Nearby Galaxy Survey data set. The results are compared with two models for exotic cold DM: internally consistent cosmological Navarro-Frenk-White (NFW) models with constrained compactness parameters, and ``universal rotation curve'' (URC) models using fully unconstrained Burkert density profiles. Fits to spiral galaxy rotation curves computed using just HI scaling are inadequate, despite the clear proportionality seen in the outer discs. The poor performance is obviously related to the prominent decrease in the HI surface density in regions of high stellar surface density, where HI has been converted into molecules and stars. The Bosma models that partially correct for this physical effect using the stellar discs as additional proxies are statistically nearly as good as the URC models and clearly better than the NFW ones. We confirm the correlation between the centripetal effects of DM and that of the interstellar medium of spiral galaxies. The efficacy of ``maximal disc'' models is explained as the natural consequence of ``classic'' Bosma models which include the stellar disc as a proxy in regions of reduced atomic gas. The perception that the Bosma effect could be due to the near-equality of the HI surface density and the projected mass density of a cold DM halo is incorrect, both theoretically and empirically. The standard explanation - that the effect reflects a statistical correlation between the visible and exotic DM - seems highly unlikely, given that the geometric forms and hence centripetal signatures of spherical halo and disc components are so different. A literal interpretation of the Bosma effect as being due to the presence of significant amounts of disc DM requires a median visible baryon to disc DM ratio of about 40%.

Abstract Copyright:

Journal keyword(s): galaxies: ISM - galaxies: kinematics and dynamics - galaxies: spiral - galaxies: structure - dark matter

Simbad objects: 17

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Number of rows : 17

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 925 H2G 02 27 16.913 +33 34 43.97   10.69 10.12 9.55   ~ 694 1
2 NGC 2366 H2G 07 28 51.85 +69 12 31.1 12.25 11.86 11.39 11.33   ~ 703 0
3 NGC 2403 AGN 07 36 51.396 +65 36 09.17 9.31 8.84 8.38 8.19   ~ 1608 1
4 NGC 2841 LIN 09 22 02.655 +50 58 35.32 10.43 10.09 9.22     ~ 986 1
5 NGC 2905 H2G 09 32 10.111 +21 30 02.99 10.44 9.75 9.07 8.68   ~ 986 3
6 NGC 2976 GiP 09 47 15.458 +67 54 58.97 11.77 11.03 10.16 9.51   ~ 581 1
7 M 81 Sy2 09 55 33.17306143 +69 03 55.0609270   7.89 6.94     ~ 3965 5
8 NGC 3198 EmG 10 19 54.990 +45 32 58.88 10.83 10.87 10.33     ~ 815 1
9 IC 2574 G 10 28 23.6204574649 +68 24 43.441365350 11.70 11.07 10.87 10.74   ~ 604 1
10 NGC 3521 LSB 11 05 48.5676206040 -00 02 09.228156576 10.06 9.83 9.02 10.1 9.6 ~ 696 2
11 NGC 3621 AGN 11 18 16.300 -32 48 45.36 10.10 9.44 9.56 8.07 10.1 ~ 488 3
12 M 94 SyG 12 50 53.148 +41 07 12.55 9.15 8.96 8.24 7.78   ~ 1217 3
13 UGC 8024 GiC 12 54 05.248 +27 08 58.67 14.37 14.23 13.95 13.84   ~ 532 1
14 M 63 LIN 13 15 49.2738527699 +42 01 45.726078017   9.34 8.59 8.35   ~ 1056 2
15 NGC 6946 H2G 20 34 52.332 +60 09 13.24   10.5       ~ 2235 2
16 NGC 7331 LIN 22 37 04.102 +34 24 57.31 10.65 10.35 9.48     ~ 1110 2
17 NGC 7793 GiG 23 57 49.7533807411 -32 35 27.708304655 10.26 9.74 9.28 9.06 9.7 ~ 922 2

    Equat.    Gal    SGal    Ecl

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2020.07.13-08:22:06

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