TUNA Lunch Talk:

Urvashi Rau

New Mexico Tech/NRAO

Multi-Frequency Synthesis Imaging for the EVLA

January 29

12:10PM, Room 230, NRAO, Edgemont Road


With new broadband receivers, visibility measurements from a wide range of frequencies can be combined to increase uv-coverage and sensitivity during synthesis imaging. The goal is to produce a high dynamic range continuum image with noise levels consistent with the broad-band sensitivity. Standard methods suffice for sources whose spectra remain flat across the observed frequency range, but for others, deconvolution algorithms need to be augmented to account for flux variation across the band. Failure to do so, can limit the achievable dynamic range to 1000:1 for a source with spectral index of 1.0 across a 2:1 bandwidth.

In this talk, I will first motivate the problem of multi-frequency synthesis(MFS) imaging, discuss existing MFS algorithms and their limitations, and describe algorithms that I am currently exploring as part of my phd thesis work. I will briefly describe a proposed astrophysical application to M87, using which I hope to establish a viable data reduction technique for broad-band EVLA observations.