Non-parametric Star-formation Histories with LIGHTNING

Rafael Eufrasio

NASA Goddard Space Flight Center
Physics Department, The Catholic University of America

Wed, January 15, 2020 - 4:00 PM
Karl Herzfeld Auditorium of Hannan Hall - Rm 108

rafael-eufrasio_photo-smr.pngVirtually all our knowledge of the history of the universe comes from the light emitted by gas and stars since the recombination epoch. In order to best determine the history of galaxies, we make use of observations from tens of telescopes, from X-rays to radio, on the ground and in space. In this talk, we present non-parametric star-formation histories (SFHs) of deep-field galaxies, as well as resolved, nearby galaxies. We explore the capabilities of LIGHTNING (Eufrasio et al. 2017), a new spectral energy distribution (SED) fitting procedure, capable of quickly and reliably recovering star formation history (SFH) and dust attenuation parameters. We employ the code to model SFHs as discrete steps in time, with lookback times of 0–10 Myr, 10–100 Myr, 0.1–1 Gyr, 1–5 Gyr, and 5–13.6 Gyr. There are many advantages in modeling the SFH as "non-parametric" steps, as it retrieves SFHs have no pre-conceived shape and therefore more reliable stellar masses and star-formation rates. We present applications of these SFHs to decompose the IR spectrum (Eufrasio et a. 2017), as well as the X-ray luminosity functions (Lehmer et al. 2017), across the M51 interacting system into different ages. We describe how our procedure allows us to break any map of a galaxy into components associated with different stellar ages, i.e., derive an empirical evolution of that emission component with the underlying stellar population age. We also present the recent expansion of this analysis to a sample of 65 resolved, nearby galaxies and thousands of galaxies in the GOODS (North and South) fields.

Refreshments served at 3:45 PM

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