Herschel View of the Warm Molecular Gas in the LMC Star-forming region N159W Min-Young Lee CEA-Saclay, France Collaborators S. Madden, V. Lebouteiller, A. Gusdorf, B. Godard, R. Wu, M. Galametz, D. Cormier, F. Le Petit, E. Roueff + SAGE/HERITAGE Survey Teams

Inflow Atomic Gas (HI) Giant Molecular Cloud (H 2 ) Star Formation Outflow “Galactic Ecology” + SNe, AGNs, galaxy-galaxy interactions …

Why CO Rotational Lines? To Probe Physical Processes in the ISM Ground-based Herschel SPIRE Fourier Transform Spectrometer (FTS) CO Spectral Line Energy Distribution (CO SLED) As a Diagnostic Tool UV (e.g., Rigopoulou+13; Lu+14; Kohler+14) X-ray (e.g., van der Werf+10; Israel+14) Mechanical (e.g., Rangwala+11; Kamenetzky+12; Pellegrini+13) CO Integrated Intensity Upper J Kamenetzky+14

CO(1–0) FTS LMC N159W: Test Bed for UV/X-ray/Shock Excitation 3.6 μm 8 μm 24 μm CO(1–0) Main FTS lines in N159W CO(4–3), …, CO(12–11) [CI] 609 and 370 μm [NII] 205 μm 30 Doradus N158/159/160 complex Molecular ridge N159W N159E N159S CO(12–11) [NII] CO(4–3) [CI]

CO SLEDs Suggest Spatial Variations in Physical Conditions CO(6–5) at 42” (10 pc) 40 pc Ground-based: Mopra CO(1–0) and ASTE CO(3–2) Lee et al, submitted J=6–5 J=5–4 24 μm

RADEX (Non-LTE radiative transfer code; van der Tak+07) Parameters: T(kin), n(H 2 ), N(CO), and Ω CO-emitting Gas in N159W on 10 pc Scales: Very Warm and Moderately Dense A single component fit 400 K 2000 cm -3

Data (42” or 10 pc scales) PACS [OI] 145 μm and [CII] 158 μm SPIRE FTS [CI] 370 μm L(FIR) from dust modeling (Galametz+13) + Meudon PDR Le Petit+06; Godard et al. in prep P G UV Z = 0.5 Z  A V = 0.5 mag Powering the CO Emission in N159W: UV Heating is Not Sufficient OB stars YSOs PACS (42”) PDR tracers G UV ~ 100 G 0 P ~ 10 6 K cm -3 CO lines Obs Model × 500 Discrepancy in both the amplitude (up to a factor of a few 1000) and shape of the CO SLED!

LMC X-1: L X ~ erg s -1 PACS (42”) Powering the CO Emission in N159W: X-ray Heating Is Insignificant Meudon PDR + X-ray w/o X-ray w/ X-ray

Paris-Durham Model Flower+10; Gusdorf+15 n(pre-shock) = 10 4 cm -3 v(shock) = 6, 10, 14 km s -1 6 km s km s km s -1 1D stationary C-type shocks w/ Powering the CO Emission in N159W: Low-velocity C-type Shocks Dominate! N159W “HI overdensity region”: Milky-Way-MC interactions? 40 pc Large-scale processes are likely the primary drivers!

Take-home Messages Future Work 1. The CO-emitting gas in LMC N159W is very warm (T(kin) ~ 400 K) and moderately dense (n(H 2 ) ~ 2000 cm -3 ). 2. UV/X-ray heating are not dominant and mechanical heating by low-velocity C-type shocks (~10 km s -1 ) is sufficient to sustain the warm CO gas. 1. Follow-up SOFIA ([OI] and [CII]) and ATCA (SiO) observations 2. Other star-forming regions in the LMC

A V = 3 mag

n(pre-shock) = 1e3

n(pre-shock) = 1e5 or v(shock) > 10 km/s