Mapping Hydrogen in the Galaxy, Galactic Halo, and Local Group with ALFA: The GALFA-HI Survey Starting with TOGS

TL;DR

The GALFA-HI survey utilizes the Arecibo telescope's ALFA instrument to map neutral hydrogen across the Milky Way and Local Group, providing high-resolution data crucial for understanding galactic systems.

Contribution

This paper introduces the GALFA-HI survey's initial results from the TOGS phase, showcasing unprecedented sensitivity and coverage in HI 21cm line observations.

Findings

Mapping thousands of square degrees of the sky.

High-resolution velocity data of interstellar gas.

Complementary data for extragalactic surveys.

Abstract

Radio observations of gas in the Milky Way and Local Group are vital for understanding how galaxies function as systems. The unique sensitivity of Arecibo's 305m dish, coupled with the 7-beam Arecibo L-Band Feed Array (ALFA), provides an unparalleled tool for investigating the full range of interstellar phenomena traced by the HI 21cm line. The GALFA (Galactic ALFA) HI Survey is mapping the entire Arecibo sky over a velocity range of -700 to +700 km/s with 0.2 km/s velocity channels and an angular resolution of 3.4 arcminutes. We present highlights from the TOGS (Turn on GALFA Survey) portion of GALFA-HI, which is covering thousands of square degrees in commensal drift scan observations with the ALFALFA and AGES extragalactic ALFA surveys. This work is supported in part by the National Astronomy and Ionosphere Center, operated by Cornell University under cooperative agreement with the National Science Foundation.