2026-04-13T03:06:29Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1282692025-12-05T16:13:39Zcom_2072_1057col_2072_478904col_2072_478917

00925njm 22002777a 4500 dc Díaz-Santos, T. author Armus, L. author Charmandaris, V. author Lu, N. author Stierwalt, S. author Stacey, G. author Malhotra, Sunny author Werf, P.P.V.D. author Howell, J. H. author Privon, G. C. author Mazzarella, J. M. author Goldsmith, P. F. author Murphy, E. J. author Barcos-Muñoz, L. author Linden, S.T. author Inami, H. author Larson, K. L. author Evans, A. S. author Appleton, P. author Iwasawa, Kazushi author Lord, S. author Sanders, D. B. author Surace, J. A. author 2019-02-14T15:15:42Z 2019-02-14T15:15:42Z 2017-09-01 2019-02-14T15:15:42Z We present an analysis of [OI]63, [OIII]88, [NII]122 and [CII]158 far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ~240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey (GOALS). We find pronounced declines -deficits- of line-to-FIR-continuum emission for [NII]122, [OI]63 and [CII]158 as a function of FIR color and infrared luminosity surface density, $\Sigma_{\rm IR}$. The median electron density of the ionized gas in LIRGs, based on the [NII]122/[NII]205 ratio, is $n_{\rm e}$ = 41 cm$^{-3}$. We find that the dispersion in the [CII]158 deficit of LIRGs is attributed to a varying fractional contribution of photo-dissociation-regions (PDRs) to the observed [CII]158 emission, f([CII]PDR) = [CII]PDR/[CII], which increases from ~60% to ~95% in the warmest LIRGs. The [OI]63/[CII]158PDR ratio is tightly correlated with the PDR gas kinetic temperature in sources where [OI]63 is not optically-thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, $n_{\rm H}$, and intensity of the interstellar radiation field, in units of G$_0$, and find G$_0$/$n_{\rm H}$ ratios ~0.1-50 cm$^3$, with ULIRGs populating the upper end of the distribution. There is a relation between G$_0$/$n_{\rm H}$ and $\Sigma_{\rm IR}$, showing a critical break at $\Sigma_{\rm IR}^{\star}$ ~ 5 x 10$^{10}$ Lsun/kpc$^2$. Below $\Sigma_{\rm IR}^{\star}$, G$_0$/$n_{\rm H}$ remains constant, ~0.32 cm$^3$, and variations in $\Sigma_{\rm IR}$ are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above $\Sigma_{\rm IR}^{\star}$, G$_0$/$n_{\rm H}$ increases rapidly with $\Sigma_{\rm IR}$, signaling a departure from the typical PDR conditions found in normal star-forming galaxies towards more intense/harder radiation fields and compact geometries typical of starbursting sources. Evolució de les galàxies Astronomia infraroja Galaxies evolution Infrared astronomy A Herschel/PACS Far-infrared line emission survey of local luminous infrared galaxies