Dark Matter within High Surface Brightness Spiral Galaxies

2003 ◽  
Vol 586 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Thilo Kranz ◽  
Adrianne Slyz ◽  
Hans‐Walter Rix
Keyword(s):  
Dark Matter ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
High Surface ◽  
High Surface Brightness

scholarly journals The σc — Vcirc correlation in high and low surface brightness galaxies

2004 ◽  
Vol 220 ◽  
pp. 339-340 ◽  
Author(s):  
A. Pizzella ◽  
E. Dalla Bontà ◽  
E. M. Corsini ◽  
L. Coccato ◽  
F. Bertola
Keyword(s):  
Surface Brightness ◽  
Velocity Dispersion ◽  
Spiral Galaxies ◽  
High Surface ◽  
Linear Scale ◽  
High Surface Brightness ◽  
Circular Velocity ◽  
Straight Line ◽  
Low Surface Brightness ◽  
Low Surface Brightness Galaxies

We investigate the relation between the central velocity dispersion, σc, and the circular velocity, Vcirc, in galaxies. in addition to previously obtained data, we consider an observationally homogeneus sample of 52 high surface brightness and 11 low surface brightness spiral galaxies. We performed a straight line regression analysis in a linear scale, finding a good fit, also for low σc galaxies, always rejected in the previous studies. Low surface brightness galaxies seem to behave differently, showing either higher values of Vcirc or lower values of σc with respect to their high surface brightness counterparts.

scholarly journals Morphology and Stellar Populations in the Gas-Rich, Giant LSBGs

1999 ◽  
Vol 171 ◽  
pp. 191-195 ◽  
Author(s):  
P. Knezek
Keyword(s):  
Entire Range ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
High Surface ◽  
Nuclear Spectroscopy ◽  
Nuclear Activity ◽  
High Surface Brightness ◽  
Low Surface Brightness ◽  
Show Evidence ◽  
Low Surface Brightness Galaxies

AbstractAn unexpected characteristic of low surface brightness galaxies (LSBGs) is that a significant number are massive and possess substantial amounts of atomic gas. We present preliminary results of an ongoing program to obtain BVRIJHK imaging, along with some nuclear spectroscopy, of a well-defined sample of LSBGs which are gas-rich and of similar size to giant, high surface brightness spiral galaxies (HSBGs). These LSBGs span the entire range of Hubble disk morphologies. While their disks are bluer, on average, than comparable HSBGs, the optical morphology of massive LSBGs indicates that many of these systems have undergone previous star formation episodes. They typically have long disk scale lengths, and range from MB = −16 to −22 (H0 = 75 km s−1 Mpc−1). About half of the LSBGs with bulges show evidence of nuclear activity, and ~30% appear to be barred. These massive, gas-rich LSBGs apparently have varied, and often complex, evolutionary histories.

Comparison of Modeling SPARC spiral galaxies’ rotation curves: halo models vs. MOND

2021 ◽  
Vol 21 (11) ◽  
pp. 271
Author(s):  
Lin Wang ◽  
Da-Ming Chen
Keyword(s):  
Dark Matter ◽  
Surface Brightness ◽  
Spiral Galaxies ◽  
High Surface ◽  
Universal Constant ◽  
Dark Halo ◽  
Rotation Curves ◽  
Average Value ◽  
Standard Value ◽  
Lsb Galaxies

Abstract The tension between luminous matter and dynamical matter has long been an interesting and controversial topic in the investigation of galaxies. This is particularly true when we study spiral galaxies for which we have high quality observations of rotation curves. The solutions to the tension are proposed in two different approaches, one is the dark matter hypothesis and the other is MOdified Newtonian Dynamics (MOND) theory. When we test the solutions by using observational data of rotation curves, the controversy arises when we apply them to both low surface brightness (LSB) galaxies and high surface brightness (HSB) galaxies. Usually one likes to use the rotation curves of LSB galaxies, since dark matter is needed or the Newtonian acceleration falls below the characteristic acceleration a 0 in most regions of such galaxies, even near their centers. But for HSB galaxies, dark matter is needed or Newtonian acceleration falls below the characteristic acceleration a 0 only in their outer regions so it is helpful to single out HSB galaxies from some large sample to test the solutions. To this end, we employ a sub-sample of the rotation curves consisting of 45 non-bulgy HSB galaxies selected from the Spitzer Photometry and Accurate Rotation Curves (SPARC) database to test two dark halo models (NFW and Burkert) and MOND. We find that, among the three models, the core-dominated Burkert halo model ( χ ν 2 = 1.00 ) provides a better description of the observed data than the NFW model ( χ ν 2 = 1.44 ) or MOND model ( χ ν 2 = 1.87 ). This is not consistent with the most recent numerical simulations, which tend to favor some cuspy density profiles for HSB galaxies. For MOND, when we take a 0 as a free parameter, there is no obvious correlation between a 0 and disk central surface brightness at 3.6 μm of these HSB spiral galaxies, which is in line with the basic assumption of MOND that a 0 should be a universal constant, but is surprisingly not consistent with the results when LSB galaxies are included. Furthermore, our fittings give a 0 an average value of (0.74 ±0.45) ×10−8 cm s−2, which only marginally supports the standard value of a 0 (1.21 ×10−8 cm s−2). Since the standard value of a 0 is strongly supported when both HSB and LSB galaxies are included in the large SPARC sample, we conclude that our slightly smaller value of a 0 cannot be explained by the so called external field effect in MOND theory.

scholarly journals X-ray Interferometry

2001 ◽  
Vol 205 ◽  
pp. 457-462
Author(s):  
Webster Cash
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Surface Brightness ◽  
High Surface ◽  
X Rays ◽  
High Surface Brightness ◽  
X Ray

X-rays have tremendous potential for imaging at the highest angular resulution. The high surface brightness of many x-ray sources will reveal angular scales heretofore thought unreachable. The short wavelengths make instrumentation compact and baselines short. We discuss how practical x-ray interferometers can be built for astronomy using existing technology. We describe the Maxim Pathfinder and Maxim missions which will achieve 100 and 0.1 micro-arcsecond imaging respectively. The science to be tackled with resolution of up to one million times that of HST will be outlined, with emphasis on eventually imaging the event horizon of a black hole.

NGC 2899: An Evolved Bipolar Planetary Nebula

1989 ◽  
Vol 131 ◽  
pp. 179-179
Author(s):  
J. A. López ◽  
L. H. Falcón ◽  
M. T. Ruiz ◽  
M. Roth
Keyword(s):  
Planetary Nebula ◽  
Surface Brightness ◽  
High Surface ◽  
Angular Size ◽  
Minor Axis ◽  
Bipolar Structure ◽  
High Surface Brightness ◽  
Central Object ◽  
Toroidal Geometry

NGC 2899 (PK 277-3°l, He 2-30, RCW 43) is a southern planetary nebula of fairly large angular size (∼2!6 × 1!4) and moderate high surface brightness. Its morphology strongly resembles a loose bipolar structure with conspicuous bright condensations of toroidal geometry placed along the minor axis, on each side of the central object.

scholarly journals Properties of Dark Matter Halos in Disk Galaxies

2004 ◽  
Vol 220 ◽  
pp. 281-286 ◽  
Author(s):  
Roelof S. de Jong ◽  
Susan Kassin ◽  
Eric F. Bell ◽  
Stéphane Courteau
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Momentum Distribution ◽  
Surface Brightness ◽  
High Surface ◽  
Large Set ◽  
Dark Matter Halos ◽  
Rotation Curves ◽  
Galaxy Assembly ◽  
Adiabatic Contraction

We present a simple technique to estimate mass-to-light (M/L) ratios of stellar populations based on two broadband photometry measurements, i.e. a colour-M/L relation. We apply the colour-M/L relation to galaxy rotation curves, using a large set of galaxies that span a great range in Hubble type, luminosity and scale size and that have accurately measured HI and/or Hα rotation curves. Using the colour-M/L relation, we construct stellar mass models of the galaxies and derive the dark matter contribution to the rotation curves.We compare our dark matter rotation curves with adiabatically contracted Navarro, Frenk, & White (1997, NFW hereafter) dark matter halos. We find that before adiabatic contraction most high surface brightness galaxies and some low surface brightness galaxies are well fit by a NFW dark matter profile. However, after adiabatic contraction, most galaxies are poorly fit in the central few kpc. the observed angular momentum distribution in the baryonic component is poorly matched by ACDM model predictions, indicating that the angular momentum distribution is not conserved during the galaxy assembly process. We find that in most galaxies the dark matter distribution can be derived by scaling up the HI gas contribution. However, we find no consistent value for the scaling factor among all the galaxies.

scholarly journals A MULTIWAVELENGTH STUDY OF THE HIGH SURFACE BRIGHTNESS HOT SPOT IN PKS 1421–490

2009 ◽  
Vol 695 (1) ◽  
pp. 707-723 ◽  
Author(s):  
L. E. H. Godfrey ◽  
G. V. Bicknell ◽  
J. E. J. Lovell ◽  
D. L. Jauncey ◽  
J. Gelbord ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Hot Spot ◽  
High Surface ◽  
High Surface Brightness
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