Zobrazeno 1 - 10
of 197
pro vyhledávání: '"Shields, Gregory"'
We separately assess elemental abundances in AGNs' broad and narrow emission line regions (BLR and NLR), based on a critical assessment of published results together with new photoionization models. We find 1) He/H enhancements in some AGN, exceeding
Externí odkaz:
http://arxiv.org/abs/2308.15761
Publikováno v:
In Future Healthcare Journal July 2023 10(2):119-123
Autor:
Phillips, M. M., Simon, Joshua D., Morrell, Nidia, Burns, Christopher R., Cox, Nick L. J., Foley, Ryan J., Karakas, Amanda I., Patat, F., Sternberg, A., Williams, R. E., Gal-Yam, A., Hsiao, E. Y., Leonard, D. C., Persson, Sven E., Stritzinger, Maximilian, Thompson, I. B., Campillay, Abdo, Contreras, Carlos, Folatelli, Gastón, Freedman, Wendy L., Hamuy, Mario, Roth, Miguel, Shields, Gregory A., Suntzeff, Nicholas B., Chomiuk, Laura, Ivans, Inese I., Madore, Barry F., Penprase, B. E., Perley, Daniel, Preston, G. Pignata G., Soderberg, Alicia M.
High-dispersion observations of the Na I D 5890, 5896 and K I 7665, 7699 interstellar lines, and the diffuse interstellar band at 5780 Angstroms in the spectra of 32 Type Ia supernovae are used as an independent means of probing dust extinction. We s
Externí odkaz:
http://arxiv.org/abs/1311.0147
We analyze the galactic H I content and nebular log(O/H) for 60 spiral galaxies in the Moustakas et al. (2006) spectral catalog. After correcting for the mass-metallicity relationship, we show that the spirals in cluster environments show a positive
Externí odkaz:
http://arxiv.org/abs/1306.2262
Autor:
Salviander, Sarah, Shields, Gregory A.
We assess evolution in the black hole mass - stellar velocity dispersion relationship (M-sigma relationship) for quasars in the Sloan Digital Sky Survey Data Release 7 for the redshift range 0.1 < z < 1.2. We estimate the black hole mass using the "p
Externí odkaz:
http://arxiv.org/abs/1210.7263
Autor:
Foley, Ryan J., Simon, Joshua D., Burns, Christopher R., Gal-Yam, Avishay, Hamuy, Mario, Kirshner, Robert P., Morrell, Nidia I., Phillips, Mark M., Shields, Gregory A., Sternberg, Assaf
Comparing the ejecta velocities at maximum brightness and narrow circumstellar/interstellar Na D absorption line profiles of a sample of 23 Type Ia supernovae (SNe Ia), we determine that the properties of SN Ia progenitor systems and explosions are i
Externí odkaz:
http://arxiv.org/abs/1203.2916
Publikováno v:
2012 ApJ, 748, 48
We study the influence of cluster environment on the chemical evolution of spiral galaxies in the Pegasus I cluster. We determine the gas-phase heavy element abundances of six galaxies in Pegasus derived from H II region spectra obtained from integra
Externí odkaz:
http://arxiv.org/abs/1112.5975
Publikováno v:
Astrophys. J. 721 (2010), 1835-1842
Active galactic nuclei (AGN) have Fe II emission from the broad line region (BLR) that differs greatly in strength from object to object. We examine the role of the total and gas-phase iron abundance in determining Fe II strength. Using AGN spectra f
Externí odkaz:
http://arxiv.org/abs/1006.2043
Recent spectropolarimetry of QSOs has revealed a surprising rise in polarization in the Lyman continuum of several objects. We discuss several recent attempts to interpret this feature, including the role of Lyman limit absorption in PG 1222+228. We
Externí odkaz:
http://arxiv.org/abs/astro-ph/0010073