Image Details
Caption: Figure 3.
Top: spatial distribution of PS1 RRab stars (circles) in the vicinity of the newly discovered outer Virgo overdensity (VOD). The gray patch indicates the location and the extent of the overdensity, and the orange solid circles show the positions of RRab stars that are spatially consistent with the overdensity. The ﹩{\tilde{B}}_{\odot }=-9^\circ ﹩ latitude in the Sgr coordinate system is illustrated by the solid line. Bottom: distribution of outer VOD RRab stars (orange solid circles in the top panel) in the distance modulus, as measured by (1) binning the data in 0.06 mag bins (gray histogram), (2) running Gaussian kernel density estimation on the data (blue solid line, kernel bandwidth is 0.06 mag), and (3) by fitting two Gaussians to the data (dashed lines, the orange solid line shows their sum). The optimal kernel bandwidth and the number of Gaussians were determined using 10-fold cross-validation.
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