Magnetic Fields, Star Formation Rates and Gas Densities at Sub-kpc Scales in a Pilot Sample of Nearby Galaxies

Abstract

We have estimated the magnetic field strengths of a sample of seven galaxies using their non-thermal synchrotron radio emission at metre wavelengths, and assuming energy equipartition between magnetic fields and cosmic ray particles. Spatially resolved star formation rates (SFR) were estimated for the seven galaxies along with five galaxies studied previously. For the combined sample of twelve galaxies, the equipartition magnetic fields (B${}_{\text{eq}}$) are correlated with the SFR surface densities (${\Sigma }_{\text{SFR}}$) at sub-kpc scales with B${}_{\text{eq}}$ $\propto$ ${\Sigma }_{\text{SFR}}^{0.31\pm 0.06}$, consistent with model predictions. We estimated gas densities (${\rho }_{\text{gas}}$) for a sub-sample of seven galaxies using archival observations of the carbon monoxide (CO) rotational transitions and the atomic hydrogen (HI) 21 cm line and studied the spatially-resolved correlation between the magnetic fields and ${\rho }_{\text{gas}}$. Magnetic fields and gas densities are found to be correlated at sub-kpc scale as B${}_{\text{eq}}$ $\propto$ ${\rho }_{\text{gas}}^{0.40\pm 0.09}$. This is broadly consistent with models, which typically predict B $\propto$ ${\rho }_{\text{gas}}^{0.5}$.

20 pages, 6 figures; accepted for publication in ApJ

References in corpus (23)

• An H-alpha Imaging Survey of Galaxies in the Local 11 Mpc Volume
• Revised equipartition & minimum energy formula for magnetic field strength estimates from radio synchrotron observations
• On the Origin of Cosmic Magnetic Fields
• Magnetic Fields in Starburst Galaxies and The Origin of the FIR-Radio Correlation
• The effect of magnetic fields on star cluster formation
• UV Dust Attenuation in Star-forming Galaxies: II Calibrating the A(UV) vs. L_TIR/L_UV relation
• Galactic dynamo and helicity losses through fountain flow
• Cosmic rays and the magnetic field of the nearby starburst galaxy NGC 253
• SLUG - Stochastically Lighting Up Galaxies. II: Quantifying the Effects of Stochasticity on Star Formation Rate Indicators
• Connecting Far-Infrared and Radio Morphologies of Disk Galaxies: Cosmic-Ray Electron Diffusion After Star Formation Episodes
• Extragalactic Zeeman Detections in OH Megamasers
• The Radio Continuum-Star Formation Rate Relation in WSRT SINGS Galaxies
• The spatially resolved Kennicutt-Schmidt relation in the HI dominated regions of spiral and dwarf irregular galaxies
• Evidence for supernova feedback sustaining gas turbulence in nearby star-forming galaxies
• CHANG-ES XXII: Coherent Magnetic Fields in the Halos of Spiral Galaxies
• Discovery of a strong spiral magnetic field crossing the inner pseudoring of NGC 4736
• Emission Line Properties of Seyfert Galaxies in the 12 Micron Sample
• The far-infrared - radio correlation in dwarf galaxies
• New insights into the interstellar medium of the dwarf galaxy IC 10: connection between magnetic fields, the radio--infrared correlation and star formation
• Magnetic fields and star formation in low-mass Magellanic-type and peculiar galaxies
• Magnetic Fields and Galactic Star Formation Rates
• On the Kennicutt-Schmidt scaling law of submillimetre galaxies
• Low radio frequency observations of seven nearby galaxies with GMRT

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