Misc,
The stellar Initial Mass Function of the solar neighbourhood revealed by Gaia
(2019)cite arxiv:1904.05646Comment: 19 pages, 12 figures, submitted to MNRAS.
Abstract
I use a sample of more than 130,000 stars in the solar neighbourhood with
parallaxes, magnitudes and colours estimated with unprecedented accuracy by the
second data release of the Gaia mission to derive the initial mass function of
the Galactic disc. A full-forward technique is employed to take into account
for the population of unresolved binaries, the metallicity distribution, the
star formation history and their variation across the Galactic disk as well as
all the observational effects. The shape of the initial mass function is well
represented by a segmented power-law with two characteristic break masses. It
has a peak at M~0.15 Ms with a significant depletion of lower mass stars and a
slope of alpha=-1.42 +/- 0.08 in the range 0.15 < M/Ms < 1. Above 1 Ms the IMF
shows an abrupt decline with a slope alpha=-2.69 +/- 0.16, steeper than a
Salpeter (1955) law. The comparison with the mass functions estimated in
unevolved stellar systems suggests a variation incompatible with the quoted
uncertainties which might be interpreted as a genuine primordial variation or
as due to a significant intrinsic variance.
