Mass modelling of a superthin galaxy, FGC1540
  We present high resolution H{\sc i} 21cm Giant Meterwave Radio Telescope
(GMRT) observations of the superthin galaxy FGC1540 with a spatial resolution
of 10$''$ $\times$ 8$''$ and a spectral resolution of 1.73 kms$^{-1}$ and an
rms noise of 0.9 mJy per beam. We obtain its rotation curve as well as
deprojected radial H{\sc i} surface density profile by fitting a 3-dimensional
tilted ring model directly to the H{\sc i} data cubes by using the
publicly-available software, Fully Automated Tirrific (FAT). We also present
the rotation curve of FGC1540 derived from its optical spectroscopy study using
the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian
Academy of Sciences. We use the rotation curve, the H{\sc i} surface density
profile together with Spitzer 3.6 $\mu$m and the SDSS $i$--band data to
construct the mass models for FGC1540. We find that both the Pseudo-isothermal
(PIS), as well as Navarro-Frenk-White (NFW) dark matter (DM) halos, fit the
observed rotation curve equally well. The PIS model indicates a compact dark
matter halo ($R_{\rm C}/R_{\rm D}$ < 2), with the best-fitting core radius
($R_{\rm C}$) approximately half the exponential stellar disc scale length
($R_{\rm D}$), which is in agreement with the mass models of superthin galaxies
studied earlier in the literature. Since the vertical thickness of the galactic
stellar disc is determined by a balance between the net gravitational field and
the velocity dispersion in the vertical direction, the compact dark matter halo
may be primarily responsible in regulating the superthin vertical structure of
the stellar disc in FGC1540 as was found in case of the superthin galaxy
UGC7321.
