摘要：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 (∼6pc) and the slit length was 14″ (∼240 pc). The spectral resolution was ∼74,000, unprecedentedly high for galactic nuclei observations at ∼2.1μm. 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 kms −1 (FWZI), and broad component FWHM∼400km s −1 , the highest detected in a nearby galaxy. At the IRC, the blueshifted broad component displays a 90 kms −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 (−215km 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.
关键词：galaxies: individual (NGC 253);galaxies: kinematics and dynamics;galaxies: nuclei;infrared: galaxies
