What can the Occult do for you? STarlight Attenuation & Reddening Survey of Multiple Occulting Galaxies (STARSMOG)

TL;DR

The STARSMOG survey uses occulting galaxy pairs observed by HST to precisely map dust distribution and extinction properties in galaxies, improving understanding of interstellar dust's impact on astronomical measurements.

Contribution

This study introduces a high-resolution mapping technique of galactic dust using occulting galaxy pairs, combining HST imaging and integral field spectroscopy for detailed dust characterization.

Findings

High-resolution dust maps of foreground galaxies

Measurement of extinction curves across different galaxy types

Insights into dust evolution over cosmic time

Abstract

Interstellar dust is still the dominant uncertainty in Astronomy, limiting precision in e.g., cosmological distance estimates and models of how light is re-processed within a galaxy. When a foreground galaxy serendipitously overlaps a more distant one, the latter backlights the dusty structures in the nearer foreground galaxy. Such an overlapping or occulting galaxy pair can be used to measure the distribution of dust in the closest galaxy with great accuracy. The STARSMOG program uses HST observation of occulting galaxy pairs to accurately map the distribution of dust in foreground galaxies in fine ($<$100 pc) detail. Furthermore, Integral Field Unit observations of such pairs will map the effective extinction curve in these occulting galaxies, disentangling the role of fine-scale geometry and grain composition on the path of light through a galaxy. The overlapping galaxy technique promises to deliver a clear understanding of the dust in galaxies: the dust geometry, a probability function of the amount of dimming as a function of galaxy type, its dependence on wavelength, and evolution of all these properties with cosmic time using distant, high-redshift pairs.