Ignacio Ferreras (UCL/IAC)

When: Friday, November 22, 2024, 2:30 PM - 3:30 PM
Where: GO Jones 610

The information limit of galaxy spectra: A tricky inverse problem

The vast majority of the observable space in astrophysics comes as
photons. Spectra therefore represent an optimal source of
information. In extragalactic astrophysics, the stellar component
produces most of the radiant energy in the rest-frame NUV-optical-NIR
window, and mainly consists of a superposition of absorption lines
overlaid on a continuum. These photons encode the properties of the
photospheres of stars, covering a wide and complex range of mass, age
and chemical composition. Population synthesis models have allowed us
to interpret the observations, mapping stellar / chemical enrichment
histories into photo-spectroscopic observables that can be "inverted"
to derive constraints on the underlying stellar content of galaxies.
In this talk I will give an overview of the standard methodology, and
discuss the difficulties underlying the analysis of stellar
populations from observable data, and explain, from an information
theory approach, the caveats of traditional methods aimed at
extracting formation histories from spectra. A data driven method
based on the covariance matrix is exploited to assess the validity of
cosmological simulations of galaxy formation.