2:00–3:00 pm ERC 419
Host: Anowar Shajib
Erik Zaborowski (Ohio State University) "Finding Strong Gravitational Lenses with Machine Learning in DELVE"
Strong gravitational lensing systems are powerful tools for astrophysics and cosmology, and machine learning has become a similarly powerful tool for identifying these systems. I will present our recent search for strong lens systems in data from the DECam Local Volume Exploration (DELVE) Survey, where we use a convolutional neural network (CNN) combined with two rounds of visual inspection to identify 617 strong lens candidates, 599 of which are previously unreported. I will then compare our results to those of other strong lens searches. Due to the location of our search footprint in the northern Galactic cap (b > 10 deg) and southern celestial hemisphere (Dec. < 0 deg), our candidate list has little overlap with other existing ground-based searches. Where our search footprint does overlap with other searches, we find a significant number of high-quality candidates which were previously unidentified, indicating a degree of orthogonality in our methodology.
Manuel Solimano (Universidad Diego Portales, Chile) "The nature of a strongly-lensed pair of merging galaxies within a Lyman-α halo at z=3: insights from MUSE and ALMA"
Spatially extended halos of H I Lyman Alpha (Lyα) emission are now ubiquitously found around high-redshift star-forming galaxies. But our understanding of the nature and powering mechanisms of these halos is still hampered by the complex radiative transfer effects of the Lyα line and the limited angular resolution afforded by standard IFU observations. In this talk, I will present the analysis of Multi Unit Spectroscopic Exlorer (MUSE) observations of SGASJ1226, a strongly-lensed pair of L* galaxies at z=2.92 embedded in a bright Lyα halo (Solimano+22). The combination of the MUSE capabilities with the extreme lensing magnification of the source allowed us to resolve gas properties down to sub-kpc scales. We find that the Lyα line width and peak velocity are correlated and vary significantly across the halo, although the line shape is consistently redshifted and asymmetric. Such a line profile is characteristic of resonant scatter of Lyα photons in galactic outflows, a picture that is further supported by the presence of blueshifted low-ionization metal lines toward the central galaxies. Radiative transfer modeling of the line in 24 PSF-independent spatial bins was used to derive a map of the intrinsic outflow velocity. This map yields an average of ~200 km/s, a value that matches the metal absorption velocity. We also identify a UV ultra-faint (M_1500 ~ -16.7) companion detected in both Lyα and continuum. Its properties resemble those of a long predicted population of satellites that make up a fraction of the extended Lyα emission. Finally, I will show some preliminary results from our ALMA follow-up of the [CII] 158µm line in SGASJ1226. Since [CII] is a non-resonant transition and is not affected by dust extinction, we obtain a clearer view of the internal kinematics of the system, which allow us to assess the impact of the interaction between the central galaxies on the properties of the halo.