Luminous Infrared Galaxies. III. Multiple Merger, Extended Massive Star Formation, Galactic Wind, and Nuclear Inflow in NGC 3256

Abstract

We report detailed evidence for: multiple merger, extended massive star formation, galactic-wind and circular/non-circular motions in the luminous infrared galaxy NGC 3256. Based on observation of high resolution imaging (obtained at HST and ESO-NTT), and extensive kinematical/spectroscopic data (more than 1000 spectra, collected at Bosque Alegre, CASLEO, CTIO and IUE Observatories).We find in a detailed morphological study (at ∼15 pc resolution) that the extended massive star formation process, detected previously in NGC 3256shows: (i) extended triple asymmetrical spiral arms structure (r ∼ 5 kpc); and (ii) the spiral arms emanate from three different nuclei. The main optical nucleus shows a small spiral-disk (r ∼ 500 pc) which is a continuation of the external one and reach the very nucleus. And this very nucleus shows blue elongate structure (63 pc × 30 pc), and luminous blue star cluster properties.We discuss this complex morphology, in the framework of an extended massive star formation driven by multiple merger process (Hernquist et al., Taniguchi et al.'s models).We study the kinematics of this system and present a detailed Hα velocity field for the central region (40 ′′ ×40 ′′ ; r max ∼30 ′′ ∼5 kpc); with a spatial resolution of 1 ′′ , and errors of ±15 km s −1 . The color and isovelocity maps show mainly: (i) a clear kinematical center of circular motion with "spider" shape and located between the main optical nucleus and the close (5 ′′ ) mid-IR knot/nucleus; (ii) non-circular motions in the external parts. In the main optical nucleus we found a clear "outflow component" associated to galactic-winds and a "inflow radial motion" (in the spiral-disk nuclear structure, r ∼700 pc). In addition, we detected the outflow component in the central and external regions

VLT-SINFONI integral field spectroscopy of low-zluminous and ultraluminous infrared galaxies

“…Most of the LIRGs of the sample are spiral galaxies with some different levels of interaction, ranging from isolated galaxies as ESO 320-G030 to close interacting systems as IC 4687+IC 4686 or mergers like NGC 3256 (Lípari et al 2000), and to objects that show long tidal tails several kiloparsecs away from its nucleus (e. g. NGC 7130, Fig. 1i).…”

“…The Brγ map shows a very clumpy morphology, with multiple knots of strong emission spread along the southern spiral arm of the object (see Lípari et al 2000Lípari et al , 2004Alonso-Herrero et al 2006, and references therein). The H 2 emission also shows a clumpy distribution with a more diffuse component and two bright spots of strong compact emission in the south of the secondary nucleus (aperture "A", Fig.…”

Gemini Spectroscopic Survey of Young Star Clusters in Merging/Interacting Galaxies. I. NGC 3256 Tidal Tail Clusters

“…This relative line-of-sight (LOS) velocity was computed from ∆v = (cz hel − cz hel,sys )/(1 + z hel,sys ), where the denominator is a relativistic correction and the systemic velocity of NGC 3256 is cz hel,sys = 2818 ± 3 km s −1 . The latter velocity is the straight average of four high-quality values published in the literature: 2820 ± 15 (Feast & Robertson 1978), 2817 ± 10 ( Lípari et al 2000), and 2820 ± 11 km s −1 from Hα-velocity mapping, and 2814 ± 11 km s −1 from the H I velocity profile (Koribalski et al 2004).…”

Galaxy-Wide Shocks in Late-Merger Stage Luminous Infrared Galaxies

“…Lira et al (2002) estimate the total F Hα ∼ 2 × 10 −11 ergs s −1 cm −2 , with data from Lípari et al (2000) using a larger aperture than is available to our IFS data. Applying a total reddening correction of E(B − V ) = 0.5, approximated using maps of the balmer decrement from our data cubes, yields L Hα ∼ 1.2 × 10 43 ergs s −1 .…”