The Herschel Comprehensive (U)lirg Emission Survey (Hercules): Co Ladders, Fine Structure Lines, and Neutral Gas Cooling
Artikel i vetenskaplig tidskrift, 2015
(Ultra) luminous infrared galaxies ((U)LIRGs) are objects characterized by their extreme infrared (8-1000 mu m) luminosities (L-LIRG > 10(11) L-circle dot and L-ULIRG > 10(12) L-circle dot). The Herschel Comprehensive ULIRG Emission Survey (PI: van derWerf) presents a representative flux-limited sample of 29 (U)LIRGs that spans the full luminosity range of these objects (10(11)L(circle dot) <= L-IR <= 10(13)L(circle dot)). With the Herschel Space Observatory, we observe [CII] 157 mu m, [O I] 63 mu m, and [O I] 145 mu m line emission with Photodetector Array Camera and Spectrometer, CO J = 4-3 through J = 13-12, [C I] 370 mu m, and [C I] 609 mu m with SPIRE, and low-J CO transitions with ground-based telescopes. The CO ladders of the sample are separated into three classes based on their excitation level. In 13 of the galaxies, the [O I] 63 mu m emission line is self absorbed. Comparing the CO excitation to the InfraRed Astronomical Satellite 60/100 mu m ratio and to far infrared luminosity, we find that the CO excitation is more correlated to the far infrared colors. We present cooling budgets for the galaxies and find fine-structure line flux deficits in the [C II], [Si II], [O I], and [C I] lines in the objects with the highest far IR fluxes, but do not observe this for CO 4 <= J(upp) <= 13. In order to study the heating of the molecular gas, we present a combination of three diagnostic quantities to help determine the dominant heating source. Using the CO excitation, the CO J = 1-0 linewidth, and the active galactic nucleus (AGN) contribution, we conclude that galaxies with large CO linewidths always have high-excitation CO ladders, and often low AGN contributions, suggesting that mechanical heating is important.
galaxies: individual (ULIRGs)
photon-dominated region (PDR)
galaxies: ISM
molecular data
submillimeter: ISM
Författare
M. J. F. Rosenberg
Universiteit Leiden
P.P. van der Werf
Universiteit Leiden
Susanne Aalto
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
L. Armus
Spitzer Science Center
V. Charmandaris
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Panepistimio Kritis
National Observatory of Athens
T. Diaz-Santos
Spitzer Science Center
A. S. Evans
University of Virginia
National Radio Astronomy Observatory
J. Fischer
Naval Research Laboratory
Y. Gao
Chinese Academy of Sciences
E. Gonzalez-Alfonso
Universidad de Alcala
T. R. Greve
University College London (UCL)
A. I. Harris
University of Maryland
C. Henkel
Max-Planck-Gesellschaft
King Abdulaziz University
F. P. Israel
Universiteit Leiden
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
R. Meijerink
Universiteit Leiden
D. A. Naylor
University of Lethbridge
D. B. Sanders
University of Hawaii
H. A. Smith
Harvard-Smithsonian Center for Astrophysics
M. Spaans
Rijksuniversiteit Groningen
L. Spinoglio
Istituto nazionale di astrofisica (INAF)
G. J. Stacey
Cornell University
I. Veenendaal
University of Lethbridge
S. Veilleux
University of Maryland
F. Walter
Max-Planck-Gesellschaft
A. Weiss
Max-Planck-Gesellschaft
M. C. Wiedner
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. H. D. van der Wiel
University of Lethbridge
E. M. Xilouris
National Observatory of Athens
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 801 2 72Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1088/0004-637x/801/2/72