1 research outputs found
Fossil evidence for spin alignment of SDSS galaxies in filaments
We search for and find fossil evidence that the distribution of the spin axes
of galaxies in cosmic web filaments relative to their host filaments are not
randomly distributed. This would indicate that the action of large scale tidal
torques effected the alignments of galaxies located in cosmic filaments. To
this end, we constructed a catalogue of clean filaments containing edge-on
galaxies. We started by applying the Multiscale Morphology Filter (MMF)
technique to the galaxies in a redshift-distortion corrected version of the
Sloan Digital Sky Survey DR5. From that sample we extracted those 426 filaments
that contained edge-on galaxies (b/a < 0.2). These filaments were then visually
classified relative to a variety of quality criteria. Statistical analysis
using "feature measures" indicates that the distribution of orientations of
these edge-on galaxies relative to their parent filament deviate significantly
from what would be expected on the basis of a random distribution of
orientations. The interpretation of this result may not be immediately
apparent, but it is easy to identify a population of 14 objects whose spin axes
are aligned perpendicular to the spine of the parent filament (\cos \theta <
0.2). The candidate objects are found in relatively less dense filaments. This
might be expected since galaxies in such locations suffer less interaction with
surrounding galaxies, and consequently better preserve their tidally induced
orientations relative to the parent filament. The technique of searching for
fossil evidence of alignment yields relatively few candidate objects, but it
does not suffer from the dilution effects inherent in correlation analysis of
large samples.Comment: 20 pages, 19 figures, slightly revised and upgraded version, accepted
for publication by MNRAS. For high-res version see
http://www.astro.rug.nl/~weygaert/SpinAlignJones.rev.pd