A Catalog of Galactic Atomic Hydrogen Position–Position–Velocity Filaments

Abstract We present a catalog of 3D Galactic H I filaments over one-third of the sky using Galactic Arecibo L -band Feed Array H I data. The 3D filaments are defined to be linear H I features that are continuous in position–position–velocity (PPV) space and are found with fil3d , an algorithm that expands on the 2D FilFinder . The catalog contains 3333 H I filaments between ±50 km s −1 at a range of Galactic positions. One thousand five hundred and forty-two of the PPV filaments are identified as local at the distance of the wall of the Local Bubble, and 209 are likely at the disk–halo interface of our Galaxy. The catalog and properties of the PPV filaments are obtained after an unsharp mask (USM) is applied to the data. The widths of the filaments are consistently ∼12 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> </mml:msup> </mml:math> (0.34 pc at 100 pc), and constrained by the 4 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow/> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> </mml:msup> </mml:math> resolution. The local filaments have median properties of N HI(med) (USM) = 6 × 10 18 cm −2 , M HI = 0.17 M ⊙ , FWHM = 3.2 km s −1 , and a length of 6.4 pc. The disk–halo population has similar column densities, but the median FWHM = 7.7 km s −1 , consistent with them being higher z height, warmer structures. The L ∝ M 0.5 relationship found for the H I filaments and their bundling on the sky are consistent with a hierarchical structure, and are likely related to turbulence playing a role in their formation.