The Spectral Energy Distribution of CO lines in M82
By A. Weiss, F. Walter, N. Scoville. 2005
133 citations recorded by the source corpus.
We present an analysis of the excitation conditions of the molecular gas in the streamers and the outflow of M82 based on observations obtained at the IRAM 30m telescope. Our analysis of J=1-0 and J=2-1 transitions of CO and 13CO and the CO(3-2) line in 13 regions outside the central starburst disk shows that the gas density within the streamer/outflow system is about an orderof magnitude lower (n(H2) ~ 10^3 cm^-3) than in the central molecular disk. We have used an LVG model and data from the literature to constrain the flux density in each CO transition (the `CO line SED') arising from the streamer/outflow system and the central starburst disk itself. Globally, we find that the CO flux density up to the J=3-2 line is dominated by the diffuse outer regions while lines above the J=5-4 transition are almost exclusively emitted by the central starburst disk. We compare the CO line SED of M82 to CO observations of galaxies at high redshift and suggest that small high-J/low-J CO flux density ratios (observed in some of these sources) are not necessarily caused by a different excitation of the central molecular gas concentration, but may result from an additional, more extended and diffuse gas reservoir around these systems, reminiscent of the situation in M82.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/4249741c09bc50680cc7bf0862dc22e10a95b413
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Citations in the corpus
- Submillimeter Galaxies at z ~ 2: Evidence for Major Mergers and Constraints on Lifetimes, IMF, and CO-H2 Conversion Factor (2008, methodology): “Gas Masses We estimated gas masses from the observed CO(3Y2) line luminosities, with a suitable CO line luminosity to H2 (+He) mass conversion factor, and assuming a brightness temperature ratio of CO(3Y2) to (1Y0) of unity, motivated by the findings of Weiss et al. (2005, 2007).”
- A 158 μm [C ii] LINE SURVEY OF GALAXIES AT z ∼ 1–2: AN INDICATOR OF STAR FORMATION IN THE EARLY UNIVERSE (2010, background): “…(e.g., Downes & Solomon 1998; Bradford et al. 2003; Weiss et al. 2005b; Ward et al. 2003; Israel 2009) and in several high-redshift systems (e.g., Weiss et al. 2005a; Aravena et al. 2008) appears to agree that to a good approximation, the integrated line flux (W m−2) ratios for the…”
- THE MOLECULAR GAS IN LUMINOUS INFRARED GALAXIES. II. EXTREME PHYSICAL CONDITIONS AND THEIR EFFECTS ON THE Xco FACTOR (2012, background): “…∼40′′ of this galaxy where the starburst takes place, a massive molecular gas reservoir with low densities, highly unbound gas motions, and low CO line excitation can still exist beyond it, a situation actually encountered in M82 in the form large scale molecular gas outflows (Weiss et al. 2005).”
- IMAGING THE MOLECULAR GAS IN A SUBMILLIMETER GALAXY AT z = 4.05: COLD MODE ACCRETION OR A MAJOR MERGER? (2010, methodology): “…our two component CO excitation model for GN20 to the inner disk of the Milky Way, the starburst regions of NGC 253 (inner few hundred parsecs), and the FIR hyper-luminous (LFIR ∼ 10 13 L⊙) host galaxy of the z = 4.7 quasar BR1202-0725 (see Weiss et al. 2005; Riechers et al. 2006 for details).”
- Highly-excited CO emission in APM 08279+5255 at z = 3.9 (2007, background): “We have recently reported observations for the gravitationally lensed galaxy SMM J16359+6612 (Weiss et al. 2005a).”
- CO(J = 1→0) IN z > 2 QUASAR HOST GALAXIES: NO EVIDENCE FOR EXTENDED MOLECULAR GAS RESERVOIRS (2006, methodology): “All these LVG calculations use the collision rates fromFlower&Pineau des Forets CO(1Y0) IN z k 4 QSOs 609No. 2, 2006 (2001) with an ortho/para H2 ratio of 3 and a CO abundance per velocity gradient of ½CO / dv/drð Þ ¼ 1 ; 10 5 pc (km s 1) 1 (e.g., Weiss et al. 2005).”