Open AccessRecovery of transverse velocities of steadily rotating patterns in flat galaxies
Author(s) -
Sridhar S.,
Sambhus Niranjan
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06953.x
Subject(s) - physics , transverse plane , vector field , galaxy , rotational symmetry , surface brightness , kinematics , brightness , radial velocity , astrophysics , classical mechanics , optics , mechanics , stars , structural engineering , engineering
The transverse velocities of steadily rotating, non‐axisymmetric patterns in flat galaxies may be determined by a purely kinematic method, using two‐dimensional maps of a tracer surface brightness and radial current density. The data maps could be viewed as the zeroth and first velocity moments of the line‐of‐sight velocity distribution, which is the natural output of integral‐field spectrographs. Our method is closely related to the Tremaine–Weinberg method of estimating pattern speeds of steadily rotating patterns, when the tracer surface brightness satisfies a source‐free continuity equation. We prove that, under identical assumptions concerning the pattern, two‐dimensional maps may be used to recover not just one number (the pattern speed), but the full vector field of tracer flow in the disc plane. We illustrate the recovery process by applying it to simulated data and test its robustness by including the effects of noise.