On the non-thermal kappa-distributed electrons in planetary nebulae and HII regions: the kappa index and its correlations with other nebular properties

Abstract

Recently, a suspicion arose that the free electrons in planetary nebulae (PNe) and HII regions might have non-thermal energy distributions. In this scenario, a kappa index is introduced to characterize the electron energy distributions, with smaller kappa values indicating larger deviations from Maxwell-Boltzmann distributions. Assuming that this is the case, we determine the kappa values for a sample of PNe and HII regions by comparing the intensities of [OIII] collisionally excited lines and the hydrogen Balmer jump. We find the average kappa indices of PNe and HII regions to be 27 and 32, respectively. Correlations between the resultant kappa values and various physical properties of the nebulae are examined to explore the potential origin of non-thermal electrons in photoionized gaseous nebulae. However, no positive result is obtained. Thus the current analysis does not lend to support to the idea that kappa-distributed electrons are present in PNe and HII regions.

23 pages, 6 figures, accepted for publication in ApJ

References in corpus (13)

• Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons
• Keck HIRES Spectroscopy of Extragalactic HII Regions: C and O Abundances from Recombination Lines
• On the abundance discrepancy problem in HII regions
• The oxygen abundance in the inner HII regions of M101. Implications for the calibration of strong-line metallicity indicators
• Chemical abundances for Hf 2-2, a planetary nebula with the strongest known heavy element recombination lines
• Elemental abundances of Galactic bulge planetary nebulae from optical recombination lines
• Suprathermal Electrons in the Solar Corona: Can Nonlocal Transport Explain Heliospheric Charge States?
• Faint recombination lines in Galactic PNe with [WC] nucleus
• Bayesian posterior classification of planetary nebulae according to the Peimbert types
• Electron Temperatures and Free-Electron Energy Distributions of Nebulae from C II Dielectronic Recombination Lines
• Emission and recombination coefficients for hydrogen with kappa-distributed electron energies
• Effective collision strengths for excitation and de-excitation of nebular [O III] optical and infrared lines with kappa distributed electron energies
• Extreme CII emission in type 2 quasars at z~2.5: a signature of kappa-distributed electron energies?

Cited by in corpus (9)

• Young stars and ionized nebulae in M83: comparing chemical abundances at high metallicity
• Recombination coefficients for O II lines in nebular conditions
• Electron Energy Distributions in HII Regions and Planetary Nebulae: kappa-Distributions Do Not Apply
• NEBULAR: A simple synthesis code for the hydrogen and helium nebular spectrum
• The ultraviolet CII lines as a diagnostic of kappa-distributed electrons in planetary nebulae
• Physical and chemical properties of Wolf-Rayet planetary nebulae
• Electron Energy Distributions in the Extended Gas Nebulae associated with High-z AGN: Maxwell-Boltzmann vs. kappa distributions
• Physical conditions and chemical abundances in photoionized nebulae from optical spectra
• Can the Kappa-distributed electron energies account for the intensity ratios of O II lines in photoionized gaseous nebulae?