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We have found an isolated polar disk galaxy in what appears to be a cosmological wall situated between two voids. This void galaxy is unique as its polar disk was discovered serendipitously in an HI survey of SDSS void galaxies, with no optical counterpart to the HI polar disk. Yet the HI mass in the disk is comparable to the stellar mass in the galaxy. This suggests slow accretion of the HI material at a relatively recent time. There is also a hint of a warp in the outer parts of the HI disk. The central, stellar disk appears relatively blue, with faint near UV emission, and is oriented (roughly) parallel to the surrounding wall, implying gas accretion from out of the voids. The considerable gas mass and apparent lack of stars in the polar disk, coupled with the general underdensity of the environment, supports recent theories of cold flow accretion as an alternate formation mechanism for polar disk galaxies.
To study the impact of sparsity and galaxy bias on void statistics, we use a single large-volume, high-resolution N-body simulation to compare voids in multiple levels of subsampled dark matter, halo populations, and mock galaxies from a Halo Occupat
Galaxies accrete material from the environment through acquisition and merging events. We study the nearby S0 galaxy IC 5181 to address the origin of the ionized-gas component orbiting the galaxy on polar orbit ionized gas of IC 5181 from broad and n
We compute the galaxy-galaxy correlation function of low-luminosity SDSS-DR7 galaxies $(-20 < M_{rm r} - 5log_{10}(h) < -18)$ inside cosmic voids identified in a volume limited sample of galaxies at $z=0.085$. To identify voids, we use bright galaxie
We apply the Alcock-Paczynski (AP) test to the stacked voids identified using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Re
Context. The prototype of Polar Ring Galaxies NGC 4650A contains two main structural components, a central spheroid, which is the host galaxy, and an extended polar disk. Both photometric and kinematic studies revealed that these two components co-ex