Center for Astrophysics Research and Technologies Seminar Series
Herschel Spectroscopy of Far-Infrared Lines in Normal Dwarf Galaxies: The View with LITTLE THINGS
Presented by Phil Cigan (NMT)
Dwarf galaxies present interesting observational challenges for the studies of various galaxy properties: depsite their numbers and proximity to the Milky Way, they typcially have very low surface brightness and physical size. Atmospheric attenuation makes far-infrared (FIR) fine-structure lines particularly hard to detect. Until now, only the extreme variety of dwarfs - those undergoing strong bouts of star formation - have been observed in the FIR, due to observational difficulties. However, the majority of dwarfs have only moderate star formation rates, and they have extremely low metallicity (the fraction of heavy elements to hydrogen). This majority of dwarf galaxy types has been very poorly studied in the FIR.
The advent of the Herschel Space Telescope has made it possible to measure several FIR atomic lines in normal and typical dwarf galaxies. The FIR spectral lines are diagnostics for the conditions in the interstellar media (ISM) of galaxies, telling us about heating efficiency, the fraction of gas that resides in photodissociation regions (PDRs), abundance of highly ionized gas from massive stars, and other physical descriptions. The LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes, The HI Nearby Galaxy Survey) project aims to unravel many mysteries of nearby dwarf galaxies using a panoply of multi-wavelength data, and our collection of complimentary spectral line and photometry data helps us to provide insight into these systems. In this talk I present observations of [CII], [OI], [OIII], and [NII] lines observed in five galaxies in the LITTLE THINGS sample, and discuss their results in relation to previous works.
2:00 pm, Thursday, November 14, 2013
PAIS-2540, PAIS
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