WALLABY Pre-Pilot Survey: Radio Continuum Properties of the Eridanus Supergroup

Abstract

We present the highest resolution and sensitivity $\sim 1.4$GHz continuum observations of the Eridanus supergroup obtained as a part of the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) pre-pilot observations using the Australian Square Kilometer Array Pathfinder (ASKAP). We detect 9461 sources at 1.37 GHz down to a flux density limit of $\sim 0.1$ mJy at $6.1^{\prime \prime }\times 7.9^{\prime \prime }$ resolution with a mean root-mean-square (RMS) of 0.05 mJy/beam. We find that the flux scale is accurate to within 5% (compared to NVSS at 1.4 GHz). We then determine the global properties of eight Eridanus supergroup members, which are detected in both radio continuum and neutral hydrogen (HI) emission, and find that the radio-derived star formation rates (SFRs) agree well with previous literature. Using our global and resolved radio continuum properties of the nearby Eridanus galaxies, we measure and extend the infrared-radio correlation (IRRC) to lower stellar masses and inferred star formation rates than before. We find the resolved IRRC to be useful for: 1) discriminating between AGN and star-forming galaxies (SFGs); 2) identifying background radio sources; and 3) tracing the effects of group environment pre-processing in NGC 1385. We find evidence for tidal interactions and ram-pressure stripping in the HI, resolved spectral index and IRRC morphologies of NGC 1385. There appears to be a spatial coincidence (in projection) of double-lobed radio jets with the central HI hole of NGC 1367. The destruction of polycyclic aromatic hydrocarbons (PAHs) by merger-induced shocks may be driving the observed WISE W3 deficit observed in NGC 1359. Our results suggest that resolved radio continuum and IRRC studies are excellent tracers of the physical processes that drive galaxy evolution and will be possible on larger sample of sources with upcoming ASKAP radio continuum surveys.

26 pages, 14 figures, Accepted for publication at PASA 23/2/2023, Full catalogues and underlying data available at: https://doi.org/10.25919/8ga8-0n09

References in corpus (16)

• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• The far-infrared/radio correlation and radio spectral index of galaxies in the SFR-M* plane up to z 2
• The Radio Spectral Energy Distribution and Star Formation Rate Calibration in Galaxies
• Powerful High Velocity-Dispersion Molecular Hydrogen Associated with an Intergalactic Shock Wave in Stephan's Quintet
• The VLA-COSMOS Survey: III. Further Catalog Analysis and the Radio Source Counts
• Connecting Far-Infrared and Radio Morphologies of Disk Galaxies: Cosmic-Ray Electron Diffusion After Star Formation Episodes
• Eridanus - A Supergroup in the Local Universe?
• Chandra Observations of Type Ia Supernovae: Upper Limits to the X-ray Flux of SN 2002bo, SN 2002ic, SN 2005gj, and SN 2005ke
• Impact of relativistic jets on the star formation rate: a turbulence-regulated framework
• The Large-Scale Atomic and Molecular Gas in the Circinus Galaxy
• Radio Source Extraction with ProFound
• Star Formation in Nearby Early-Type Galaxies: The Radio Continuum Perspective
• The Origin of Exponential Star-forming Disks
• The influence of angular momentum and environment on the HI gas of late-type galaxies
• Deciphering the radio-star formation correlation on kpc-scales I. Adaptive kernel smoothing experiments
• Resolved simulations of jet-ISM interaction: Implications for gas dynamics and star formation

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