DETERMINATION OF INTRINSIC SHAPE OF ELLIPTICAL GALAXY: NGC 2768 USING MODIFIED PRIOR

Abstract

Using the triaxial model, the intrinsic shapes of elliptical galaxies can be determined by combining the profiles of  photometeric data. These data has been taken from the literature. We have developed methodology by making a modification in the methodology described in Statler (1994). The intrinsic shape of elliptical galaxies are reported by Chakraborty et al (2008) and Singh (2011), Singh & Chakraborty (2009) and Singh (2015), Singh (2019), Singh (2019), Singh (2020) and Singh (2021) using flat as well as modified prior. We find that short to long axial ratios at very small radii and at very large radii, and the absolute value of the triaxiality difference are the best constrained shape parameters.

The result obtained by the determination of modified prior are compared with the previous results which are determined by using flat prior. We apply this methodology to a galaxy NGC 2768. The intrinsic shapes of the NGC 2768 are shown in the figures as a function of (q₀,q_∞) summed over  (T₀,T_∞) for two dimensional shape and  (q₀,q_∞,|T_d|) for three dimensional shapes, where the values of T_d are constant in each section and |T_d| is the absolute values of the triaxiality difference, defined as |T_d|= |T_∞ - T₀|.  The probability of finding the shape as  shown in the dark gray region: darker is the region higher is the probability. We find that the galaxy NGC 2768 are flatter inside and flatter outside.