Details

Autor(en) / Beteiligte

• Walter, Fabian
• Bolatto, Alberto D.
• Leroy, Adam K.
• Veilleux, Sylvain
• Warren, Steven R.
• Hodge, Jacqueline
• Levy, Rebecca C.
• Meier, David S.
• Ostriker, Eve C.
• Ott, Jürgen
• Rosolowsky, Erik
• Scoville, Nick
• Weiss, Axel
• Zschaechner, Laura
• Zwaan, Martin

Titel

Dense Molecular Gas Tracers in the Outflow of the Starburst Galaxy NGC 253

Ist Teil von

• The Astrophysical journal, 2017-02, Vol.835 (2), p.265

Ort / Verlag

Philadelphia: The American Astronomical Society

Erscheinungsjahr

2017

Link zum Volltext

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• We present a detailed study of a molecular outflow feature in the nearby starburst galaxy NGC 253 using ALMA. We find that this feature is clearly associated with the edge of NGC 253's prominent ionized outflow, has a projected length of ∼300 pc, with a width of ∼50 pc, and a velocity dispersion of ∼40 km s−1, which is consistent with an ejection from the disk about 1 Myr ago. The kinematics of the molecular gas in this feature can be interpreted (albeit not uniquely) as accelerating at a rate of 1 km s−1 pc−1. In this scenario, the gas is approaching an escape velocity at the last measured point. Strikingly, bright tracers of dense molecular gas (HCN, CN, HCO+, CS) are also detected in the molecular outflow: we measure an HCN(1-0)/CO(1-0) line ratio of in the outflow, similar to that in the central starburst region of NGC 253 and other starburst galaxies. By contrast, the HCN/CO line ratio in the NGC 253 disk is significantly lower ( ), similar to other nearby galaxy disks. This strongly suggests that the streamer gas originates from the starburst, and that its physical state does not change significantly over timescales of ∼1 Myr during its entrainment in the outflow. Simple calculations indicate that radiation pressure is not the main mechanism for driving the outflow. The presence of such dense material in molecular outflows needs to be accounted for in simulations of galactic outflows.