Mapping electron temperature variations across a spiral arm in NGC 1672

Abstract

We report one of the first extragalactic observations of electron temperature variations across a spiral arm. Using MUSE mosaic observations of the nearby galaxy NGC 1672, we measure the [N II]5755 auroral line in a sample of 80 HII regions in the eastern spiral arm of NGC1672. We discover systematic temperature variations as a function of distance perpendicular to the spiral arm. The electron temperature is lowest on the spiral arm itself and highest on the downstream side. Photoionization models of different metallicity, pressure, and age of the ionizing source are explored to understand what properties of the interstellar medium drive the observed temperature variations. An azimuthally varying metallicity appears to be the most likely cause of the temperature variations. The electron temperature measurements solidify recent discoveries of azimuthal variations of oxygen abundance based on strong lines, and rule out the possibility that the abundance variations are artefacts of the strong-line calibrations.

9 pages, 5 figure, accepted to ApJ Letter

References in corpus (9)

• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• The MUSE second-generation VLT instrument
• Metallicity gradients in local field star-forming galaxies: Insights on inflows, outflows, and the coevolution of gas, stars and metals
• CHAOS I: Direct Chemical Abundances for HII Regions in NGC 628
• Nebular spectroscopy: A guide on H II regions and planetary nebulae
• Model-based pattern speed estimates for 38 barred galaxies
• LZIFU: an emission-line fitting toolkit for integral field spectroscopy data
• The Chemical Evolution Carousel of Spiral Galaxies: Azimuthal Variations of Oxygen Abundance in NGC1365
• Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties

Cited by in corpus (9)

• Mapping metallicity variations across nearby galaxy disks
• The role of galactic dynamics in shaping the physical properties of giant molecular clouds in Milky Way-like galaxies
• Metallicity, ionization parameter, and pressure variations of HII regions in the TYPHOON spiral galaxies
• The DUVET Survey: Direct $T_e$-based metallicity mapping of metal-enriched outflows and metal-poor inflows in Mrk 1486
• PHANGS-MUSE: Detection and Bayesian classification of ~40000 ionised nebulae in nearby spiral galaxies
• A geostatistical analysis of multiscale metallicity variations in galaxies [I]: Introduction and comparison of high-resolution metallicity maps to an analytic metal transport model
• A quasar-galaxy merger at $z\sim 6.2$: rapid host growth via accretion of two massive satellite galaxies
• A physically motivated `charge-exchange method' for measuring electron temperatures within HII regions
• A novel approach to investigate chemical inhomogeneities in GRB host galaxies: The $Z_{\mathrm{abs}}-Z_{\mathrm{emiss}}$ relation