A Faint Flux-Limited LAE Sample at z = 0.3
Isak Wold, UT Austin
Observational surveys of Lya emitters (LAEs) have proven to be an efficient method to identify and study large numbers of galaxies over a wide redshift range. To understand what types of galaxies are selected in LAE surveys – and how this evolves with redshift – it is important to establish a low-redshift reference sample that can be directly compared to high-redshift samples. The lowest redshift where a direct Lya survey is currently possible is at a redshift of z~0.3 via the Galaxy Evolution Explorer (GALEX ) FUV grism data. Using the z~0.3 GALEX sample as an anchor point, it has been suggested that at low redshifts high equivalent width (EW) LAEs become less prevalent and that the amount of escaping Lya emission declines rapidly. A number of explanations for these trends have been suggested including increasing dust content, increasing neutral column density, and/or increasing metallicity of star-forming galaxies at lower redshifts. However, the published z~0.3 GALEX sample is pre-selected from bright NUV objects. Thus, objects with strong Lya emission but faint continuum (high-EW LAEs) could be missed. In this talk, I will present my efforts to re-reduce the deepest archival GALEX FUV grism data and obtain a sample that is not biased against high-EW LAEs. I will discuss the implications of this new sample on the evolutionary trends listed above.
Protoplanetary disk rotation curves and the kinematic detection of protoplanets
Simon Casassus, Universidad de Chile
Direct detections of protoplanets still embedded in a gaseous protoplanetary disk have been remarkably elusive in their thermal-IR radiation. Yet most models for the structures observed in disks involve planet/disk interactions. The gas and dust density fields are thus appealing proxies to trace embedded bodies, but they are not sufficient to ascertain a planetary origin. New hopes for protoplanet detection come from the disk kinematics, which should also bear their dynamical imprint. The last couple of years have seen the first indirect detection of protoplanets, with the observation of small deviations from Keplerian rotation in molecular line channel maps, and their reproduction in hydrodynamical simulations. Can we use the gas kinematics directly to pin-point the location and measure the dynamical mass of giant planets? The theoretical velocity reversal along the wakes of a protoplanet should be observable as a Doppler-flip, provided that the background flow is adequately subtracted. This axially symmetric flow is a generalized rotation curve, including also the radial and vertical velocity components, which bear the imprint of accretion, winds, and of the theoretical meridional flows in the case of planet/disk interactions. I will present a technique to calculate disk rotation curves, with applications to ALMA long baseline data in HD100546 and in HD163296.
The Circumgalactic Medium at Cosmic Noon with KCWI
Nikole Nielsen, Swinburne University of Technology
The star formation history of the universe reveals that galaxies most actively build their stellar mass at cosmic noon (z=1-3), roughly 10 billion years ago, with a decrease toward present-day. The resulting metal-enriched material ejected from these galaxies due to supernovae and stellar feedback is deposited into the circumgalactic medium (CGM), which is a massive reservoir of diffuse, multiphase gas out to radii of 200 kpc. The CGM is the interface between the intergalactic medium and the galaxy, through which accreting filaments of near-pristine gas must pass to contribute new star formation material to the galaxy and outflowing gas is later recycled. Simulating these baryon cycle flows is crucial for accurately modeling galaxy evolution. While the CGM is well-studied at z<1, little attention has been paid to the reservoir when star formation is most active due to the difficulty in identifying the host galaxies. The installation of the Keck Cosmic Web Imager (KCWI), an integral field spectrograph, on Keck II has opened a new window to quickly identify galaxies via their Lyman alpha emission at this redshift. I will introduce a new survey to build a catalog of absorber-galaxy pairs at z=2-3 with KCWI. With the combination of HST images, high-resolution quasar spectra, and the cutting-edge KCWI data, this survey aims to examine CGM kinematics and metallicities and relate them to the host galaxy star formation rates and orientations to reveal the baryon cycle at cosmic noon. https://nmsu.zoom.us/j/96153330256