Theoretical predictions for IMF diagnostics in UV spectroscopy of star clusters

• We explore the possibility of using UV spectroscopy in combination with broad-band photometry as diagnostic tools for understanding the shape of the initial mass function (IMF) in unresolved stellar populations. Building on our previous work, we extend the Stochastically Lighting Up Galaxies (SLUG) code to include a high-resolution UV spectral synthesizer and equivalent width calculation capabilities. We first gain a qualitative understanding of how UV spectral features behave as the parameters that define a star cluster in SLUG (mass, age, extinction, and IMF slope alpha(3)) are changed. We then exploit Bayesian inference techniques to recover the alpha(3) values for clusters simulated with SLUG, using mock observations of these clusters comprised of broad-band photometry and equivalent width measurements of a selection of UV spectral features. We find some improvement when compared to attempts using broad-band photometry alone (with the interquartile range of the alpha(3) posterior PDF shrinking by similar or equal to 32%), although we still do not yet fully break the known degeneracy between the cluster mass and alpha(3). Finally, we make predictions about how effective real observations will be by quantifying our ability to constrain alpha(3) as a function of limiting equivalent width. We find that observations sensitive to a modest equivalent width of similar or equal to 9 angstrom are sufficient to improve the recovery of the IMF slope parameter by similar or equal to 32% (interquartile range of posterior PDF median residuals), moving to similar or equal to 39% when we include all the significant spectral features in the wavelength range 900 - 3000 angstrom.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

methods: statistical

stars: luminosity function

mass function

galaxies: clusters: general

Publikations- och innehållstyp

ref (ämneskategori)

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