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It has long been recognized that interactions between galaxies are important in determining their evolution. The distribution of gas--out of which new stars are formed--is strongly affected; in particular, gas may be concentrated near the nucleus, leading to a burst of star formation. Here we present a map of atomic hydrogen (H I) in the nearest interacting group of galaxies (that dominated by M81), obtained by combining 12 separate fields observed with the Very Large Array. The H I that surrounds M81, M82 and NGC3077 (the most prominent galaxies in the group) is dominated by filamentary structures, clearly demonstrating the violent disruption of this system by tidal interactions. These observations should have detected all H I complexes more massive than 10(6) solar masses, meaning that our map contains all structures that might evolve into new dwarf galaxies.

The Submillimeter Array (SMA), a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total of eight 6-m telescopes comprise the array, which will cover the frequency range of 180-900 GHz. All eight telescopes have been deployed and are operational. First scientific results utilizing the three receiver bands at 230, 345, and 690 GHz have been obtained and are presented in the accompanying papers.Comment: 10 pages, 4 figure

The Subaru Prime Focus Spectrograph (PFS) is a massively-multiplexed fiber-fed optical and near-infrared 3-arm spectrograph (N fiber =2400, 380≤ λ ≤ 1260nm, 1.3 degree diameter hexagonal field), offering unique opportunities in survey astronomy. Following a successful external design review the instrument is now under construction with first light anticipated in late 2017. Here we summarize the science case for this unique instrument in terms of provisional plans for a Subaru Strategic Program of ≃300 nights. We describe plans to constrain the nature of dark energy via a survey of emission line galaxies spanning a comoving volume of 9.3h −3 Gpc 3 in the redshift range 0.8 < z < 2.4. In each of 6 independent redshift bins, the cosmological distances will be measured to 3% precision via the baryonic acoustic oscillation scale, and redshift-space distortion measures will be used to constrain structure growth to 6% precision. In the near-field cosmology program, radial velocities and chemical abundances of stars in the Milky Way and M31 will be used to infer the past assembly histories of spiral galaxies and the structure of their dark matter halos. Data will be secured for 10 6 stars in the Galactic thick-disk, halo and tidal streams as faint as V ∼ 22, including stars with V < 20 to complement the goals of the Gaia mission. A medium-resolution mode with R = 5, 000 to be implemented in the red arm will allow the measurement of multiple α-element abundances and more precise velocities for Galactic stars, elucidating the detailed chemo-dynamical structure and evolution of each of the main stellar components of the Milky Way Galaxy and of its dwarf spheroidal galaxies. The M31 campaign will target red giant branch stars with 21.5< V <22.5, obtaining radial velocities and metallicities over an unprecedented area of 65 deg 2 . For the extragalactic program, our simulations suggest the wide wavelength range of PFS will be particularly powerful in probing the galaxy population and its clustering over a wide redshift range. We propose to conduct a color-selected survey of 1 < z < 2 galaxies and AGN over 16 deg 2 to J ≃23.4, yielding a fair sample of galaxies with stellar masses above ∼ 10 10 M ⊙ at z ≃ 2. A two-tiered survey of higher redshift Lyman break galaxies and Lyman alpha emitters will quantify the properties of early systems close to the reionization epoch. PFS will also provide unique spectroscopic opportunities beyond these currentlyenvisaged surveys, particularly in the era of Euclid, LSST and TMT.