Interstellar extinction curve variations towards the inner Milky Way: A challenge to observational cosmology
No hay miniatura disponible
Archivos
Fecha
2016-03
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
Oxford University Press
Nombre de Curso
Licencia CC
Licencia CC
Resumen
We investigate interstellar extinction curve variations towards ∼4 deg2 of the inner Milky Way
in VIJKs photometry from the OGLE-III (third phase of the Optical Gravitational Lensing
Experiment) and VVV (VISTA Variables in the Via Lactea) surveys, with supporting evidence
from diffuse interstellar bands and F435W, F625W photometry. We obtain independent mea surements towards ∼2000 sightlines of AI, E(V − I), E(I − J) and E(J − Ks), with median
precision and accuracy of 2 per cent. We find that the variations in the extinction ratios AI/E(V
− I), E(I − J)/E(V − I) and E(J − Ks)/E(V − I) are large (exceeding 20 per cent), signifi cant and positively correlated, as expected. However, both the mean values and the trends in
these extinction ratios are drastically shifted from the predictions of Cardelli and Fitzpatrick,
regardless of how RV is varied. Furthermore, we demonstrate that variations in the shape of
the extinction curve have at least two degrees of freedom, and not one (e.g. RV), which we
confirm with a principal component analysis. We derive a median value of AV/AKs = 13.44,
which is ∼60 per cent higher than the ‘standard’ value. We show that the Wesenheit magnitude
WI = I − 1.61(I − J) is relatively impervious to extinction curve variations. Given that these
extinction curves are linchpins of observational cosmology, and that it is generally assumed
that RV variations correctly capture variations in the extinction curve, we argue that systematic
errors in the distance ladder from studies of Type Ia supernovae and Cepheids may have
been underestimated. Moreover, the reddening maps from the Planck experiment are shown to
systematically overestimate dust extinction by ∼100 per cent and lack sensitivity to extinction
curve variations.
Notas
Indexación: Scopus.
Palabras clave
Dust, Extinction, ISM: Lines and Bands
Citación
Monthly Notices of the Royal Astronomical Society. Volume 456, Issue 3, Pages 2692 - 2706. 1 March 2016
DOI
10.1093/mnras/stv2843