Radio Detection of Green Peas: Implications for Magnetic Fields in Young Galaxies

Abstract

Green Peas are a new class of young, emission line galaxies that were discovered by citizen volunteers in the Galaxy Zoo project. Their low stellar mass, low metallicity and very high star formation rates make Green Peas the nearby (z~0.2) analogs of the Lyman-break Galaxies (LBGs) which account for the bulk of the star formation in the early universe (z~2-5). They thus provide accessible laboratories in the nearby Universe for understanding star formation, supernova feedback, particle acceleration and magnetic field amplification in early galaxies. We report the first direct radio detection of Green Peas with low frequency GMRT observations and our stacking detection with archival VLA FIRST data. We show that the radio emission implies that these extremely young galaxies already have magnetic fields (>30 muG) even larger than that of the Milky Way. This is at odds with the present understanding of magnetic field growth based on amplification of seed fields by dynamo action over a galaxy's lifetime. Our observations strongly favor models with pregalactic magnetic fields at muG levels.

5 pages, 3 figures, 1 table, submitted

References in corpus (7)

• Revised equipartition & minimum energy formula for magnetic field strength estimates from radio synchrotron observations
• On the Origin of Cosmic Magnetic Fields
• Signals from the Noise: Image Stacking for Quasars in the FIRST Survey
• On the oxygen and nitrogen chemical abundances and the evolution of the "green pea" galaxies
• Star formation rates in Lyman break galaxies: radio stacking of LBGs in the COSMOS field and the sub-$\mu$Jy radio source population
• Role of Galactic sources and magnetic fields in forming the observed energy-dependent composition of ultrahigh-energy cosmic rays
• The Young and the Dustless: Interpreting Radio Observations of UltraViolet Luminous Galaxies

Cited by in corpus (18)

• The Origin and Optical Depth of Ionizing Radiation in the "Green Pea" Galaxies
• The Fast and Furious Decay of the Peculiar Type Ic Supernova 2005ek
• The Equipartition Magnetic Field Formula in Starburst Galaxies: Accounting for Pionic Secondaries and Strong Energy Losses
• Generation of Primordial Magnetic Fields on Linear Over-density Scales
• Complex gas kinematics in compact, rapidly assembling star-forming galaxies
• Chemodynamics of Green Pea galaxies -- I. Outflows and turbulence driving the escape of ionising photons and chemical enrichment
• Magnetic field amplification by the small-scale dynamo in the early Universe
• Green Peas in X-rays
• CMB spectral distortions from the decay of causally generated magnetic fields
• The Milky Way Project: What are Yellowballs?
• Hα and UV luminosities and star formation rates in a large sample of luminous compact galaxies
• Low-redshift Lyman Continuum Survey: Radio continuum properties of low-$z$ Lyman continuum emitters
• Radio properties of Green Pea galaxies
• Tracking galaxy evolution through low frequency radio continuum observations using SKA and Citizen-science Research using Multi-wavelength data
• Radio continuum emission from local analogs of high-z faint LAEs: Blueberry galaxies
• Radio observations confirm young stellar populations in local analogues to $z\sim 5$ Lyman break galaxies
• A NuSTAR and XMM-Newton Study of the Two Most Actively Star-forming Green Pea Galaxies (SDSS J0749+3337 and SDSS J0822+2241)
• Radio continuum detection in blue early-type weak emission line galaxies