I seek to study the filamentary structure of the cosmic web, from the largest scales down to the central hubs — massive galaxy clusters. My tool of choice is gravitational lensing, in particular weak lensing. I’m a member of the CLASH team and a builder of the Dark Energy Survey collaboration.
Recently, the ASAS-SN program detected a super-luminous supernova, and follow-up spectroscopy revealed that it’s the brightest one on record (cf. Dong et al. 2015). I got a request from ASAS-SN colleagues at OSU to check whether the host galaxy (identified as APMUKS(BJ) B215839.70-615403.9) is in the DES footprint. It sure is. From our latest Year-2 data we publicly released the deepest image of the host and added 5-band optical photometry to existing NIR and IR measurements. We determined the galaxy to be a massive old elliptical, highly unusual for a SLSN host.
For the first paper with data from the Dark Energy Survey, I led a large team of DES collaborators and used the Dark Energy Camera (DECam) on the CTIO 4-m telescope to study four massive galaxy clusters.
The targeted clusters were well known—one of them is the famous Bullet Cluster, the poster child of merging clusters—so that the findings from DECam data could be cross-checked with existing results. Not only did we validate the instrument and the DES analysis pipelines for the delicate task of weak lensing measurements. We utilized the entire 3 square degree field of view to investigate the large-scale environment, revealing extended filamentary features from which these cluster accrete their material.
With images and spectroscopy from SDSS, I measured, for the first time, the really weak lensing signal of cosmic voids.
The voids were identified by a sophisticated algorithm that utilizes the full three-dimensional information of positions and spectroscopic redshifts, so that we could then combine their anti-lensing effects from the tiny distortions of the shapes of backgrund galaxies. While only marginally significant (equivalent to a 2.9 σ detection), this measurement confirms that voids are as underdense in Dark Matter as they are in galaxies.