THE MASS DISTRIBUTION AND M/L RATIOS IN NGC 5953/5954

Journal Article · Fri Nov 01 04:00:00 EDT 2013 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/146/5/121· OSTI ID:22273296

Hernández Toledo, H. M.; Moreno, E.; García-Barreto, J. A. ^[1]

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1. Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P-70-264, 04350 México, D.F. (Mexico)

In this first paper, we combine a structural analysis of the near-IR surface brightness profiles and [N II] rotation curves for the galaxies in the pair NGC 5953/5954 to model the mass distribution in each member by using two independent axisymmetric analytical mass models: (1) a standard model given by the sum of a spherical bulge with the Sérsic law, a stellar exponential disk, and a cold dark matter halo represented by the improved fitting formula of Navarro et al.; and (2) a simple model given by the sum of a spherical bulge, a finite oblate spheroid representing the disk, and a spherical dark halo, all three mass components with simple density laws. In our surface brightness fits, a central luminous source is considered in both galaxies. We obtained K-band M/L ratios, Y {sub D}, Y {sub B}, for the disks and bulges, and total masses for each mass component in both galaxies. With the standard model we find in NGC 5953, (Y {sub D},Y {sub B}) = (0.29{sub -0.29}{sup +1}, 0.37 ± 0.03) M {sub ☉}/L {sub ☉}, and in NGC 5954, (Y {sub D},Y {sub B}) = (0.88 ± 0.18, 0.21 ± 0.09) M {sub ☉}/L {sub ☉}. Corresponding values found with the simple model are (Y {sub D},Y {sub B}) = (1.41 ± 0.15, 0.29 ± 0.04) M {sub ☉}/L {sub ☉} and (Y {sub D},Y {sub B}) = (0.51 ± 0.05, 0.52{sub -0.12}{sup +0.23}) M {sub ☉}/L {sub ☉}. Our M/L estimates are compared with predictions from other methods in the literature, finding reasonable agreement. The dark halos estimated using the simple model have a small mass, of the order of 10{sup 7} M {sub ☉}, within the maximum distance in the rotation velocity data.

• OSTI ID: 22273296
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 5 Vol. 146; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
AXIAL SYMMETRY
BRIGHTNESS
COMPARATIVE EVALUATIONS
DIAGRAMS
GALAXIES
MASS
MASS DISTRIBUTION
NEAR INFRARED RADIATION
NONLUMINOUS MATTER
PHOTOMETRY
ROTATION
STAR CLUSTERS