Hydrogen molecules in quasar broad-line regions

The physical conditions within dense cold clouds in cooling flows - II

“…The molecule network presently includes H − , H2, H + 2 , H + 3 , HeH + , OH, OH + , CH, CH + , O2, O + 2 , CO, CO + , H2O, H2O + , H3O + , and CH + 2 . Reaction rate coefficients are from Hollenbach and McKee (1979;; Tielens and Hollenbach (1985a), Lenzuni, Chernoff, and Salpeter (1991), Wolfire, Tielens, and Hollenbach (1990); Crosas and Weisheit (1993); Puy et al (1993), Maloney, Hollenbach, & Tielens (1996), Hollenbach & Tielens (1999), and the UMIST database (http://www.rate99.co.uk/). The resulting chemistry is in good agreement with standard PDR calculations.…”

Influence of the (n-n')-mixing processes on the optical properties of the hydrogen clouds in the broad-line region of AGNs

“…The results presented here cover the range of temperatures 2000 K ≤ T ≤ 30000 K, broader than the regions relevant for weakly ionized layers of dense parts of the BLR clouds (see e.g. Crosas & Weisheit, 1993;Negrete et al, 2012), so that the data presented here can be also used for investigation of the atmospheres of Sun and Sun-like stars etc. Srećković et al, 2014).…”

“…In active galactic nuclei (AGN), especially in the region of the moderately ionized layers of dense parts of the broad-line region (BLR), in which physical conditions are closer to stellar atmospheres than to photoionized nebulae (Ilić et al, 2007;Negrete et al, 2012;Ilić et al, 2017;Bon et al, 2018;Osterbrock & Ferland, 2006). In the BLR clouds temperature may drop to the much lower values where the gas is weakly ionized with huge number of hydrogen atoms in excited states, due to the high density and large optical depths (Crosas & Weisheit, 1993;Negrete et al, 2012;Netzer, 2013). Consequently, it is of interest to investigate the influence of the mentioned collisional processes Srećković et al (2018c).…”

The influence of collisional-ionization and recombination processes on spectral line shapes in stellar atmospheres and in the hydrogen clouds in broad-line region of AGNs

“…The processing of line spectra with radiative transfer calculations requires spectroscopic data as well as collisional data (e.g., cross sections, rate coefficients, atomic parameters, etc Baron & Hauschildt 1998;Mihajlov et al 2011a;Ignjatović et al 2014;Srećković et al 2018a). The fact that the ionization processes which involve highly excited atoms (Mihajlov et al, 2012;Srećković et al, 2017) influence the ionization level and atom excited-state populations, could influence the optical properties of the weakly ionized regions (Mihajlov et al, 2011b) of very dense parts of the clouds in broad line region (BLR) of active galactic nuclei (AGN), and potentially be important for the spectroscopy and modeling of such environment (Crosas & Weisheit, 1993;Osterbrock & Ferland, 2006).…”