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)

galaxies: ISM

submillimeter: ISM

photon-dominated region (PDR)

molecular data


M. J. F. Rosenberg

Leiden Observatory Research Institute

P.P. van der Werf

Leiden Observatory Research Institute

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

National Observatory of Athens

Panepistimio Kritis

T. Diaz-Santos

Spitzer Science Center

A. S. Evans

University of Virginia

National Radio Astronomy Observatory

J. Fischer

Naval Research Laboratory

Y. Gao

Purple Mountain Observatory Chinese Academy of Sciences

E. Gonzalez-Alfonso

Universidad de Alcala

T. R. Greve


A. I. Harris

University of Maryland

C. Henkel

King Abdulaziz University

Max Planck Institut fur Radioastronomie

F. P. Israel

Leiden Observatory Research Institute

K. Isaak


C. Kramer

Instituto de Radioastronomia Milimetrica

R. Meijerink

Leiden Observatory Research Institute

D. A. Naylor

University of Lethbridge

D. B. Sanders

University of Hawaii at Manoa

H. A. Smith

Harvard-Smithsonian Center for Astrophysics

M. Spaans

University of Groningen, Kapteyn Astronomical Institute

L. Spinoglio

Istituto Nazionale Di Astrofisica, Rome

G. J. Stacey

Cornell University

I. Veenendaal

University of Lethbridge

S. Veilleux

University of Maryland

F. Walter

Max Planck Institut fur Astronomie

A. Weiss

Max Planck Institut fur Radioastronomie

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 72


Astronomi, astrofysik och kosmologi