A SIMPLE-MODEL OF MAGNETICALLY INDUCED WARPS

Assuming the magnetic hypothesis for the formation of warps, we deduce a very simple formula for the warp curve in an idealized scenario. Ac cording to this formula the warp rises as the third power of radius in the innermost warped region, reaches the maximum slope at intermediat e radii and has an asymptotic slope coincident with the direction of t he extragalactic magnetic field. In most cases, however, the galaxy's limited size prevents the observation of the full curve. Even though t he model is highly simplified, it basically reproduces real warp curve s, in particular the 21 cm warp curve of NGC 5907. If the magnetic mod el were considered to be correct, the fitting of warp curves could all ow rough estimations of the strength and direction of the magnetic fie ld. We also propose a magnetic field distribution for the outermost pa rt of the galaxy, matching the boundary conditions of being azimuthal inside, and constant at infinity. We use this magnetic field distribut ion to show that the assumptions made to obtain the warp curve with ou r simple model cannot introduce important errors.