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Full-Text Articles in Physical Sciences and Mathematics
Nitrogen-To-Oxygen Abundance Ratio Variation In Quiescent Galaxies, Renbin Yan
Nitrogen-To-Oxygen Abundance Ratio Variation In Quiescent Galaxies, Renbin Yan
Physics and Astronomy Faculty Publications
For the first time, we establish a gas-phase abundance pattern calibration for quiescent galaxies using optical emission lines. Quiescent galaxies have warm ionized gas showing line ratios similar to low-ionization nuclear emission line regions. The ionization mechanism for the gas is still an unsettled puzzle. Despite the uncertainty in the ionization mechanism, we argue that we can still infer certain gas-phase abundance pattern from first principles. We show that the relative trend in N/O abundance can still be reliably measured based on [N II] λλ6548,6583/[O II] λλ3726,3729 and a direct measurement of the electron temperature. We construct a composite direct …
Shocks Or Photoionization: Direct Temperature Measurements Of The Low-Ionization Gas In Quiescent Galaxies, Renbin Yan
Shocks Or Photoionization: Direct Temperature Measurements Of The Low-Ionization Gas In Quiescent Galaxies, Renbin Yan
Physics and Astronomy Faculty Publications
The ionization mechanism of the low-ionization gas in quiescent red-sequence galaxies has been a long-standing puzzle. Direct temperature measurements would put strong constraints on this issue. We carefully selected a sample of quiescent red-sequence galaxies from Sloan Digital Sky Survey. We bin them into three bins with different [N II]/H α and [N II]/[O II] ratios, and we measure the temperature-sensitive [O III] λ4363, [N II] λ5755, [S II] λλ4068, 4076, and [O II] λλ7320, 7330 lines in the stacked spectra. The [S II] doublet ratios indicate the line-emitting gas is in the low-density regime (∼10–200 cm−3). We …
Intermediate-Line Emission In Agns: The Effect Of Prescription Of The Gas Density, T. P. Adhikari, K. Hryniewicz, A. Różańska, B. Czerny, Gary J. Ferland
Intermediate-Line Emission In Agns: The Effect Of Prescription Of The Gas Density, T. P. Adhikari, K. Hryniewicz, A. Różańska, B. Czerny, Gary J. Ferland
Physics and Astronomy Faculty Publications
The requirement of an intermediate-line component in the recently observed spectra of several active galactic nuclei (AGNs) points to the possible existence of a physically separate region between the broad-line region (BLR) and narrow-line region (NLR). In this paper we explore the emission from the intermediate-line region (ILR) by using photoionization simulations of the gas clouds distributed radially from the center of the AGN. The gas clouds span distances typical for the BLR, ILR, and NLR, and the appearance of dust at the sublimation radius is fully taken into account in our model. The structure of a single cloud is …