We demonstrate a novel technology that combines the power of the multi‐object spectrograph with the spatial multiplex advantage of an integral field spectrograph (IFS). The Sydney‐AAO (Australian Astronomical Observatory) Multi‐object IFS (SAMI) is a prototype wide‐field system at the Anglo‐Australian Telescope (AAT) that allows 13 imaging fibre bundles (‘hexabundles’) to be deployed over a 1‐degree diameter field of view. Each hexabundle comprises 61 lightly fused multi‐mode fibres with reduced cladding and yields a 75 per cent filling factor. Each fibre core diameter subtends 1.6 arcsec on the sky and each hexabundle has a field of view of 15 arcsec diameter. The fibres are fed to the flexible AAOmega double‐beam spectrograph, which can be used at a range of spectral resolutions (R=λ/δλ≈ 1700–13 000) over the optical spectrum (3700–9500 Å). We present the first spectroscopic results obtained with SAMI for a sample of galaxies at z≈ 0.05. We discuss the prospects of implementing hexabundles at a much higher multiplex over wider fields of view in order to carry out spatially resolved spectroscopic surveys of 104–105 galaxies.

We use a volume-limited spectroscopic sample of isolated galaxies in the Sloan Digital Sky Survey (SDSS) to investigate the frequency and radial distribution of luminous (M r −18.3) satellites like the Large Magellanic Cloud (LMC) around ∼ L * Milky Way analogs and compare our results object-by-object to ΛCDM predictions based on abundance matching in simulations. We show that 12% of Milky Way-like galaxies host an LMC-like satellite within 75 kpc (projected), and 42% within 250 kpc (projected). This implies ∼ 10% have a satellite within the distance of the LMC, and ∼ 40% of L * galaxies host a bright satellite within the virialized extent of their dark matter halos. Remarkably, the simulation reproduces the observed frequency, radial dependence, velocity distribution, and luminosity function of observed secondaries exceptionally well, suggesting that ΛCDM provides an accurate reproduction of the observed Universe to galaxies as faint as L ∼ 10 9 L on ∼ 50 kpc scales. When stacked, the observed projected pairwise velocity dispersion of these satellites is σ 160 km s −1 , in agreement with abundance-matching expectations for their host halo masses. Finally, bright satellites around L * primaries are significantly redder than typical galaxies in their luminosity range, indicating that environmental quenching is operating within galaxy-size dark matter halos that typically contain only a single bright satellite. This redness trend is in stark contrast to the Milky Way's LMC, which is unusually blue even for a field galaxy. We suggest that the LMC's discrepant color might be further evidence that it is undergoing a triggered star-formation event upon first infall.

We report new polarimetric and photometric maps of the massive star-forming region OMC-1 using the HAWC+ instrument on the Stratospheric Observatory for Infrared Astronomy (SOFIA). We present continuum polarimetric and photometric measurements of this region at 53, 89, 154, and 214

A long-standing and profound problem in astronomy is the diffi culty in obtaining deep nearinfrared observations due to the extreme brightness and variability of the night sky at these wavelengths. A solution to this problem is crucial if we are to obtain the deepest possible observations of the early Universe, as redshifted starlight from distant galaxies appears at these wavelengths. The atmospheric emission between 1,000 and 1,800 nm arises almost entirely from a forest of extremely bright, very narrow hydroxyl emission lines that varies on timescales of minutes. The astronomical community has long envisaged the prospect of selectively removing these lines, while retaining high throughput between them. Here we demonstrate such a fi lter for the fi rst time, presenting results from the fi rst on-sky tests. Its use on current 8 m telescopes and future 30 m telescopes will open up many new research avenues in the years to come.