ALMA Schedule

CASCA 2013 Schedule for S2 Alma

S2 Alma
Location: Hebb Theatre Chair: Brenda Matthews
1100 Booth, Mark ALMA Cycle 0 Image of the AU Mic Debris Disc
  Planetesimals left over from the planet formation epoch continually grind down through collisions producing vast quantities of dust. This combination of dust and planetesimals is known as a debris disc, the first examples of which were observed in 1984. The majority of debris disc observations are of the outer, cold component of the disc. ALMA is most sensitive to this cold dust and its superior resolution to any previous sub-mm telescope allows us to get a detailed view of the nearest debris discs. The debris disc around AU Mic is one of the best studied discs due to its proximity and brightness. AU Mic is also one of only a few M-type stars to harbour a debris disc. I will present the first ALMA images of the AU Mic debris disc, taken at a wavelength of 1.3mm and resolution of 0.6". I will show how, by resolving the outer disc, we detect evidence for an unresolved component to the disc, potentially analogous to our own asteroid belt. The outer dust belt is found to have roughly a lunar mass and has a rising emission profile peaking at 40 AU. The inner belt has ~0.01 lunar masses of dust and is located around 3 AU from the star.
1115 Di Francesco, James ALMA Cycle 0 Observations of Proplyds in Orion
  Protoplanetary disks, or "proplyds," are the sites where new solar systems are born. While disk studies to date have focused on regions like Taurus and Ophiuchus for their proximity, stars rarely form in such isolated environments. In fact, there is clear evidence that our own Sun formed near a clustered OB association like Orion. To understand how planets form, it is imperative that we study disk properties in regions representative of their origins. For this reason, we have observed 41 proplyds in Orion with ALMA, to study fundamental disk properties in a massive star forming region. Even in just its Cycle 0 "Early Science" phase, ALMA is uniquely capable of imaging dust and gas emission from the Orion proplyds with its combination of high frequency, sensitivity, resolution, and spatial filtering properties. These 345 GHz continuum and line observations provide the first detailed view into how the clustered environment and UV radiation affect disk properties and evolution. Ultimately, these data will allow us to assess the potential to form solar system analogues in massive star forming regions.
1130 Friesen, Rachel ALMA Observations of Clustered Star-Forming Cores in Ophiuchus
  Since most stars in our galaxy form in clusters, understanding clustered star formation has become a key goal of star formation astronomy. As a dense core collapses, however, the density progression and accompanying temperature changes result in well-documented molecular abundance variations. Chemical models predict that the molecular ion H2D+ is likely the best kinematic probe of the dense core gas most actively forming stars, but prior to ALMA, the species had only been detected by single-dish telescopes over physical scales > 2000 AU. Here, we present ALMA Cycle 0 observations of two evolved, dense cores located within the same filament in the Ophiuchus cluster-forming region. While no embedded sources are visible in Spitzer data toward either target, we propose that the two cores, separated by only ~0.02 pc (~4500 AU) in projection, are examples of highly evolved objects observed just prior to and just post the formation of an embedded young stellar object. We report the first detection of H2D+ at ~ 125 AU scales (1" FWHM at 125 pc) toward the starless core. We find no H2D+ emission toward the likely protostellar core, suggesting that sufficient CO has already been evaporated from dust grains on small scales, through protostellar heating, to reduce the H2D+ abundance. In addition, the ALMA continuum data show little evidence of substructure on ~ 60 - 700 AU scales toward either core, suggesting either that these objects will form single stellar systems, or that fragmentation occurs at a later evolutionary stage.
1145 Rosolowsky, Erik Fueling a Nuclear Starburst -- Giant Molecular Clouds in NGC 253
  We present a multi-tracer analysis of the nuclear giant molecular clouds (GMCs) seen in the nearby galaxy NGC 253 by the Atacama Large Millimetre/Submillimetre Array. Using extended configuration Cycle 0 data, we have observed dense gas tracers in the nuclear starburst region in the 3 mm dense gas tracers including HCN, HCO+, their isotopologues and several other species. The resulting data have a linear resolution of 30 pc, enabling their decomposition into individual GMCs. Using the CPROPS algorithm, we find GMCs show the characteristic features of molecular clouds found in galactic centres. There is a well defined size-line width relationship, but the clouds show turbulent motions with magnitudes a factor of 5 larger than galactic disk clouds. The luminosities of the 14 tracers correlate well with dynamical estimates of cloud masses. However, the scaling between luminosity and dynamical mass is non-linear for many of the tracers including HCN and HCO+, which are commonly cited as linear tracers of dense molecular gas. We also directly trace high mass star formation through the H40a radio recombination line and can measure the opacity of the HCN/HCO+ emission through detection of rarer isotopologues.
1200 Hezaveh, Yashar ALMA Observations of Gravitationally Lensed, High Redshift, Dusty Star Forming Galaxies
  Wide area surveys in mm-wave have discovered a large population of strongly lensed, dusty, star-forming galaxies (DSFGs) at very high redshifts (z=2-6). I will present ALMA Cycle 0 observations of a sample of strongly lensed DSFGs discovered by the South Pole Telescope, and discuss the lens models (constructed using a visibility fitting technique) which allow us to measure the intrinsic properties of the sources. Finally, I will discuss the prospects of using ALMA to detect low-mass dark matter subhalos in the lensing galaxies, through the gravitationally-induced distortions that they cause in the images of the background lensed DSFGs, allowing a new test of dark matter by constraining the small scale structure of the galactic halos.
1215 Willott, Chris An ALMA study of star formation in z=6 quasar host galaxies
  I will present results of ALMA Early Science observations of high-redshift quasars. These observations probe an order of magnitude deeper than previous work and allow us to study galaxies with modest star formation rates in the early universe. Our work compares the build-up of stellar mass and black hole accretion only 1 billion years after the Big Bang.