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We theoretically study the vertical structure of the edge-on low surfacebrightness (LSB) galaxy UGC 7321. This is one of the few well-observed LSBs. Wemodeled it as a gravitationally coupled disk system of stars and atomichydrogen gas in the potential of the dark matter halo and treated the realisticcase where the rotation velocity varies with radius. We used a dense andcompact halo as implied by the observed rotation curve in this model. Wecalculated the thickness of stellar and HI disks in terms of the half-width athalf-maximum of the vertical density distribution in a region of R=0 to 12 kpcusing input parameters constrained by observations. We obtain a mildlyincreasing disk thickness up to R=6 kpc, in a good agreement with the observedtrend, and predict a strong flaring beyond this. To obtain this trend, thestellar velocity dispersion has to fall exponentially at a rate of 3.2R_D ,while the standard value of 2R_D gives a decreasing thickness with radius.Interestingly, both stellar and HI disks show flaring in the outer disk regionalthough they are dynamically dominated by the dark matter halo from the veryinner radii. The resulting vertical stellar density distribution cannot be fitby a single sech^2/n function, in agreement with observations, which show wingsat larger distances above the mid-plane. Invoking a double-disk model toexplain the vertical structure of LSBs as done in the literature may thereforenot be necessary.

Flaring stellar disk in the low surface brightness galaxy UGC 7321