A tangle of stellar streams in the north Galactic cap

TL;DR

This paper maps and analyzes multiple stellar streams and halo structures in the north Galactic cap using SDSS data, revealing known and new substructures and measuring halo flattening.

Contribution

It provides a detailed mapping of stellar streams and halo shape in the north Galactic cap, including the identification of new candidate streams.

Findings

Identification of four known stellar streams consistent with previous measurements.

Detection of a new candidate stream, the Perpendicular Stream.

Measurement of the stellar halo's flattening parameter as q=0.58.

Abstract

Stellar halo substructures were identified using statistical photometric parallax of blue main sequence turnoff stars from fourteen Sloan Digital Sky Survey stripes in the north Galactic cap. Four structures are consistent with previous measurements of the Sagittarius dwarf tidal stream: the leading tail, the "bifurcated" stream, the trailing tail, and Stream C. The stellar overdensity in Virgo, about 15 kpc from the Sun, could arise from the crossing of the Parallel Stream and a new, candidate stream dubbed the Perpendicular Stream. The data suggests the presence of a wide stream near NGC 5466, with a distance of 5 to 15 kpc. Measurements of the flattening of the smooth stellar halo from the fourteen stripes average q=0.58, with a dispersion of 0.04.