Far ultraviolet to far infrared images of the nearby galaxy NGC 5194 (M51a), from a combination of space-based (Spitzer, GALEX, and Hubble Space Tele-1 Based on observations obtained with the Spitzer Space Telescope and with GALEX.

We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg 2 of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 ± 0.04 deg −2. The selected sources have 500 μm flux densities (S 500) greater than 100 mJy. Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems (70%), and the lensing status of the four remaining sources is undetermined. We also present a supplementary sample of 29 (0.31 ± 0.06 deg −2) gravitationally lensed SMG candidates with S 500 = 80-100 mJy, which are expected to contain a higher fraction of interlopers than the primary candidates. The number counts of the candidate lensed galaxies are consistent with a simple statistical model of the lensing rate, which uses a foreground matter distribution, the intrinsic SMG number counts, and an assumed SMG redshift distribution. The model predicts that 32%-74% of our S 500 100 mJy candidates are strongly gravitationally lensed (μ 2), with the brightest sources being the most robust; this is consistent with the observational data. Our statistical model also 1

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We present Hubble Space Telescope/NICMOS images at 0>2 resolution (Nyquist-sampled in the central 19 00 ) of the H i Pa emission line in a 70 00 ðÞ Â 90 00 ðÞ region of the Galactic center centered on the nonthermal radio source Sgr A*. The majority of the emission arises from ionized gas in the minispiral in the central parsec. Pa emission is also seen from 26 stellar sources, presumably early-type stars with mass-loss winds. The new data reveal significant small-scale structure ( 1 00 $ 1:2 Â 10 17 cm) in the ionized gas of the minispiral; low surface brightness emission features are also seen for the first time. The ratio of observed Pa emission to 6 cm radio continuum emission is used to derive an extinction map for the ionized gas over the central parsec. A V varies from 20 to 50 mag with a median value of A V ¼ 31:1 mag, in excellent agreement with earlier estimates derived for the stellar sources. Extinctions, independently derived using H92 recombination-line data, were in excellent agreement with those derived from the 6 cm continuum. A broad minimum in the extinction extends $30 00 northeast-southwest over the area of the IRS 16 cluster, including the area of peak flux in Pa and radio continuum. Large increases in extinction are seen along the periphery of the ionized gas, particularly in the direction of the western arm, suggesting that the ionized gas is partially extincted by dust in the molecular clouds at the outside of the ionized region; however, the H ii cannot be entirely behind the molecular clouds since the extinctions would then be much greater. The minimum Lyman continuum emission rate within 40 00 radius of Sgr A* is 3:9 Â 10 50 s À1 or L LyC ' 2:7 Â 10 6 L , half of this within 20 00 radius. The small-scale, filamentary structures in the ionized gas have a free thermal expansion time of only $3000 yr; either magnetic fields or mass-loss winds from the hot emission line stars may contain the ionized filaments. (Eight new emission-line stars were also detected in Pa.) For both the ionized gas and stellar continuum, the centroids of the emission (corrected for extinction) remain within $AE1 00 from a radius of 2 00 out to 40 00 . This provides further evidence that Sgr A* (the putative central black hole) is indeed at or extremely close ( 0.04 pc or 1:2 Â 10 17 cm) to the center of the Galactic nucleus stellar distribution and presumably the dynamical center of the Galaxy. The 1.9 lm surface brightness increases inwards to 0>9 radius and exhibits a decrease or leveling off closer to Sgr A*, possibly indicating the core radius of the central stellar distribution or depletion of the late-type stars by stellar collisions near the central black hole.

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