[seminar] Astro Journal Club on 28 January

[Oskari Miettinen]

Dear all,

Our Astro Journal Club will be held on Wednesday at 10:15 in the seminar
room F-201 of the Physics Department. This time we will discuss about the
stellar mass function in the high-redshift galaxies.

Presenter: Jacinta Delhaize
Paper title: The galaxy stellar mass function at 3.5<z<7.5 in the
CANDELS/UDS, GOODS-South, and HUDF fields
Authors: Grazian, A., Fontana, A., Santini, P., et al.

Abstract:
The galaxy stellar mass function (GSMF) at high-z provides key information
on star-formation history and mass assembly in the young Universe. We
aimed to use the unique combination of deep optical/NIR/MIR imaging
provided by HST, Spitzer and the VLT in the CANDELS-UDS, GOODS-South, and
HUDF fields to determine the GSMF over the redshift range 3.5<z<7.5. We
utilised the HST WFC3/IR NIR imaging from CANDELS and HUDF09, reaching
H~27-28.5 over a total area of 369 arcmin2, in combination with associated
deep HST ACS optical data, deep Spitzer IRAC imaging from the SEDS
programme, and deep Y and K-band VLT Hawk-I images from the HUGS
programme, to select a galaxy sample with high-quality photometric
redshifts. These have been calibrated with more than 150 spectroscopic
redshifts in the range 3.5<z<7.5, resulting in an overall precision of
sigma_z/(1+z)~0.037. We have determined the low-mass end of the high-z
GSMF with unprecedented precision, reaching down to masses as low as
M*~10^9 Msun at z=4 and ~6x10^9 Msun at z=7. We find that the GSMF at
3.5<z<7.5 depends only slightly on the recipes adopted to measure the
stellar masses, namely the photo-z, the SFHs, the nebular contribution or
the presence of AGN on the parent sample. The low-mass end of the GSMF is
steeper than has been found at lower redshifts, but appears to be
unchanged over the redshift range probed here. Our results are very
different from previous GSMF estimates based on
converting UV galaxy luminosity functions into mass functions via tight
M/L relations. Integrating our evolving GSMF over mass, we find that the
growth of stellar mass density is barely consistent with the time-integral
of the SFR density over cosmic time at z>4. These results confirm the
unique synergy of the CANDELS+HUDF, HUGS, and SEDS surveys for the
discovery and study of
moderate/low-mass galaxies at high redshifts.

Link to the paper: http://adsabs.harvard.edu/abs/2014arXiv1412.0532G

Hope to see you all on Wednesday!

Best regards,
Oskari Miettinen