Scalings between Physical and their Observationally related Quantities of Merger Remnants

TL;DR

This study investigates scaling relations in merger remnants of spiral galaxies through N-body simulations, revealing how different fitting methods and profiles influence the derived relations and indicating a breakdown of structural homology.

Contribution

It provides a detailed analysis of how fitting procedures and profile assumptions affect scaling relations in merger remnants, highlighting the non-homologous nature of these structures.

Findings

Scaling relations depend on fitting method and profile choice.

Dissipationless merger remnants show broken structural and kinematic homology.

Different fitting approaches yield significantly different exponents.

Abstract

We present scaling relations between the virial velocity (V) and the one-dimensional central velocity dispersion (Sig0); the gravitational radius (Rv) and the effective radius (Re); and the total mass (M) and the luminous mass (ML) found in N-body simulations of binary mergers of spiral galaxies. These scalings are of the form V^2 ~ Sig0^alpha, Rv ~ Re^beta and M ~ ML^gamma. The particlar values obtained for (alpha,beta,gamma) depend on the method of fitting used [ordinary least-squares (ols) or orthogonal distance regression (odr)], the assumed profile [de Vaucouleurs (deV) or Sersic (S)], and the size of the radial interval where the fit is done. The alpha and gamma indexes turn out more sensitive to the fitting procedure, obtaining for the ols a mean alpha_ols=1.51 and gamma_ols=0.69, while for the odr alpha_odr=2.35 and gamma_odr=0.76. The beta index depends more on the adopted type of profile, with beta_deV=0.13 and beta_S=0.27. We conclude that dissipationless formed remnants of mergers have a strong breaking of structural and kinematical homology.