Cool gas and dust in M33: Results from the Herschel M33 extended survey (HERM33ES)

Abstract

We present an analysis of the first space-based far-IR-submm observations of M 33, which measure the emission from the cool dust and resolve the giant molecular cloud complexes. With roughly half-solar abundances, M33 is a first step towards young low-metallicity galaxies where the submm may be able to provide an alternative to CO mapping to measure their H${}_2$ content. In this Letter, we measure the dust emission cross-section $\sigma$ using SPIRE and recent CO and \HI\ observations; a variation in $\sigma$ is present from a near-solar neighborhood cross-section to about half-solar with the maximum being south of the nucleus. Calculating the total H column density from the measured dust temperature and cross-section, and then subtracting the \HI\ column, yields a morphology similar to that observed in CO. The H${}_2$/\HI\ mass ratio decreases from about unity to well below 10% and is about 15% averaged over the optical disk. The single most important observation to reduce the potentially large systematic errors is to complete the CO mapping of M 33.

5 pages, 5 figures Accepted for publication in Astronomy and Astrophysics

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Cited by in corpus (28)

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• Dust and gas power-spectrum in M33 (HERM33ES)
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• Variation in the dust emissivity index across M33 with Herschel and Spitzer (HerM33es)
• Cool and warm dust emission from M33 (HerM33es)
• Simulating the interstellar medium of galaxies with radiative transfer, non-equilibrium thermochemistry, and dust
• GAMA/H-ATLAS: The Dust Opacity - Stellar Mass Surface Density Relation for Spiral Galaxies
• Properties and rotation of molecular clouds in M 33
• The Resolved Distributions of Dust Mass and Temperature in Local Group Galaxies
• The UK Infrared Telescope M33 monitoring project. V. The star formation history across the galactic disc
• The star-formation law at GMC scales in M33, the Triangulum Galaxy
• The Heating of Mid-Infrared Dust in the Nearby Galaxy M33: A Testbed for Tracing Galaxy Evolution
• Dissecting Nearby Galaxies with piXedfit: I. Spatially Resolved Properties of Stars, Dust, and Gas as Revealed by Panchromatic SED Fitting
• The molecular gas mass of M33
• Nonparametric galaxy morphology from UV to submm wavelengths
• Spectral Energy Distributions of HII regions in M33 (HerM33es)
• Minimal HCN emission from Molecular Clouds in M33
• A photoionization model of the spatial distribution of the optical and mid-IR properties in NGC595
• The Opacity of Spiral Galaxy Disks IX; Dust and Gas Surface Densities
• Massive young stellar objects in the Local Group spiral galaxy M33 identified using machine learning
• A detailed view of a Molecular Cloud in the far outer disk of M33
• Gathering dust: A galaxy-wide study of dust emission from cloud complexes in NGC 300
• Molecular Cloud Matching in CO and Dust in M33 I. High-Resolution Hydrogen Column Density Maps from Herschel
• Star formation drivers across the M33 disk
• Atomic Hydrogen produced in M33 Photodissociation Regions
• A multiwavelength analysis of the clumpy FIR-bright sources in M33
• Star formation in M33 (HerM33es)
• Compact and High Excitation Molecular Clumps in the Extended Ultraviolet Disk of M83