[seminar] Astro Journal Club on 18 February

[Oskari Miettinen]

Dear all,

The Astro Journal Club will be held on Wednesday at 10:15 in the Physics
Department's seminar room F-201. This time we won't have a traditional
paper presentation but a talk on quasar spectra by D. Milakovic.

Presenter: Dinko Milakovic
Title: Precision test of the cosmological principle using QSO spectra

Abstract:
Bulk flows of matter have been found on cosmological scales, in conflict
with the standard cosmological model, suggesting the universe is "tilted"
with respect to the cosmic microwave background (CMB) reference frame.
Similar evidence comes from WMAP data. A joint analysis of high redshift
supernovae data, CMB data, and large-scale quasar polarisation also
suggests an anisotropic universe. There may even be a link between the
apparent baryonic anisotropies and a spatial variation in the fine
structure constant. If so, this violates the Einstein equivalence
principle and may indicate that the universe extends way beyond our
observable horizon, possibly to infinity, potentially solving the
'cosmological fine-tuning problem'. If the Universe is tilted, this would
also be reflected in the cosmological distribution of neutral hydrogen.
Spectroscopy of the intervening gas seen in absorption against distant
quasars probes the evolution of the Universe from about 1 Gyr old up to
today, 14 Gyr after the Big Bang. Using observations of ~155 000 quasars
from the Sloan Digital Sky Survey, we present the highest precision
measurements to date for cosmologically distributed neutral hydrogen over
the redshift range 2.2 < z < 4.5.

Hope to see you all on Wednesday!

Best regards,
Oskari Miettinen