The Nuclear Source of the Galactic Wind in NGC 253

• Published in: The Astronomical journal Vol. 158; no. 3; pp. 115 - 123
• Main Authors: Günthardt, G. I., Díaz, R. J., Agüero, M. P., Gimeno, G., Dottori, H., Camperi, J. A.
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01.09.2019; IOP Publishing
• Subjects: Astronomy; Asymmetry; Emission lines; Galactic evolution; Galactic nuclei; Galactic winds; Galaxies; galaxies: individual (NGC 253); galaxies: kinematics and dynamics; galaxies: nuclei; Infrared astronomy; infrared: galaxies; Kinematics; Molecular gases; Radial velocity; Spatial resolution; Spectral resolution; Star & galaxy formation; Star formation; Stars & galaxies; Stellar winds; Velocity distribution; Wind
• ISSN: 0004-6256; 1538-3881
• DOI: 10.3847/1538-3881/ab2f7c

We present Brγ emission line kinematics of the nuclear region of NGC 253, recently known to host a strong galactic wind that limits the global star formation of the galaxy. We obtained high-resolution long-slit spectroscopic data with PHOENIX at Gemini South, positioning the slit on the nucleus infrared core (IRC), close to the nuclear disk major axis. The spatial resolution was 0 35 (∼6 pc) and the slit length was 14″ (∼240 pc). The spectral resolution was ∼74,000, unprecedentedly high for galactic nuclei observations at ∼2.1 m. The line profiles appear highly complex, with blue asymmetry up to 3 5 away of the IRC, and red asymmetries further away to northeast. Several Gaussian components are necessary to fit the profile, nevertheless a narrow and a wide one predominate. The IRC presents kinematic widths above 700 km s−1 (FWZI), and broad component FWHM ∼ 400 km s−1, the highest detected in a nearby galaxy. At the IRC, the blueshifted broad component displays a 90 km s−1 bump in radial velocity distribution, a feature we previously detected in molecular gas kinematics. The narrow component velocity dispersion (∼32 km s−1) is within the expected for normal galaxies and luminous infrared galaxies (LIRGs). Intermediate components (FWHM ∼ 150 km s−1, redshifted to the northeast, blueshifted to the southwest) appear at some positions, as well as weaker blue (−215 km s−1) and red line wings (+300 km s−1). The IRC depicts a large broad-versus-narrow line flux ratio (F(B)/F(N) ∼ 1.35), and the broad component seems only comparable with those observed at very high star-forming rate galaxies. The results indicate that the IRC would be the main source of the galactic winds originated in the central region of NGC 253.