Wide-field stellar distributions around the remote young galactic globular clusters Palomar 3 and Palomar 4

In a search for tidal extension features and/or streams of the probable parent satellite galaxies around the remote young globular clusters Pal 3 and Pal 4, we used wide-field VI photometry of an area a ∼ 1°.3 × 1°.3 around Pal 3 and an area a ∼ 1°.3 × 0°.9 around Pal 4, obtained with the CFH12K mosaic CCD. Applying the CMD-mask algorithm to stars in the vicinity of the clusters, we selected member star candidates that were used to examine the characteristics of the spatial distribution of stars around Pal 3 and Pal 4. The isodensity contours in the Gaussian-smoothed spatial stellar density maps around the clusters, and the Kolmogorov-Smirnov test applied to the corresponding luminosity functions, indicate tidal halos around Pal 3 at distances of up to ∼4r_t, and around Pal 4 of up to ∼6r_t. The stellar distribution around Pal 3 suggests north-south elongations along the directions of the Galactic center and anticenter, and a northeast extension in the direction of the cluster's proper motion. In the vicinity of Pal 4 an extension of a tail around the cluster in the opposite direction to the Galactic center and a possible extension of stars toward the Galactic center have also been detected in the isodensity maps and in the angular luminosity functions. We discuss the relevance of the spatial distribution of stars in possible streams around Pal 3 and Pal 4 to these spatial correlations and to the space orbits of the possible parent satellite galaxies.