Extremely Large Telescope

Abstract:

We present a detailed analysis of the spatially resolved properties of the lensed submillimeter galaxy (SMG) SMM J14011+0252 atz = 2.56, combining deep near-infrared integral-field data obtained with SPIFFI on the VLT with other multiwavelength data sets. As previously discussed by other authors, the broad characteristics of SMM J14011+0252 in particular and submillimeter galaxies in general are in agreement with what is expected for the early evolution of local massive spheroidal galaxies. From continuum and line flux, velocity, and dispersion maps, we measure the kinematics, star formation rates, gas densities, and extinction for individual subcomponents. The star formation intensity is similar to low-redshift "maximal starbursts," while the line fluxes and the dynamics of the emission line gas provide direct evidence for a starburst-driven wind with physical properties very similar to local superwinds. We also find circumstantial evidence for "self-regulated" star formation within J1. The relative velocity of the bluer companion J2 yields a dynamical mass estimate for J1 within ∼20 kpc of Mdyn ∼ 1 × 10¹¹ M⊙. The relative metallicity of J2 is 0.4 dex lower than in J1n/J1s, suggesting different star formation histories. Spectral energy distribution fitting of the continuum peak J1c confirms and substantiates previous suggestions that this component is a z = 0.25 interloper. When removing J1c, the stellar continuum and Hα line emission appear well aligned spatially in two individual components, J1n and J1s, and coincide with two kinematically distinct regions in the velocity map, which might well indicate a merging system. This highlights the close similarity between SMGs and ultraluminous infrared galaxies (ULIRGs), which are often mergerdriven maximal starbursts, and suggests that the intrinsic mechanisms of star formation and related feedback are in fact similar to low-redshift strongly star-forming systems. © 2007. The American Astronomical Society. All rights reserved.

Abstract:

Using integral-field spectroscopy, the SAURON survey has shown that early-type galaxies, once thought to be essentially devoid of gas, commonly show ionised gas emission. This emission is found with a rich variety of distributions and kinematics, ranging from very uniform disks or rings, and large-scale twisted structures, to flocculent and irregular streams. Such variety is missed in conventional long-slit spectroscopy, and integral-field spectroscopic data allow accurate removal of the underlying stellar continuum compared with imaging surveys, giving very low detection limits. Moreover, spectral data can simultaneously provide the stellar kinematics and populations as well as the emission-line properties. We investigate the connection between the stellar and gas properties using integral-field spectroscopy from SAURON, OASIS and GMOS, and find that, although some global trends exist, the connection between the stellar population parameters and the gas properties is in some cases puzzlingly unclear. (c) 2006 Elsevier B.V. All rights reserved.

Abstract:

By detecting ionised-gas emission in 75% of the cases, the SAURON integral-field spectroscopic survey has further demonstrated that early-type galaxies often display nebular emission. Furthermore, the SAURON data have shown that such emission comes with an intriguing variety of morphologies, kinematic behaviours and line ratios. Perhaps most puzzling was the finding that round and slowly rotating objects generally display uncorrelated stellar and gaseous angular momenta, consistent with an external origin for the gas, whereas flatter and fast rotating galaxies host preferentially co-rotating gas and stars, suggesting internal production of gas. Alternatively, a bias against the internal production of ionised gas and against the acquisition of retrograde material may be present in these two kinds of objects, respectively. In light of the different content of hot gas in these systems, with slowly rotating objects being the only systems capable of hosting massive X-ray halos, we suggest that a varying importance of evaporation of warm gas in the hot interstellar medium can contribute to explain the difference in the relative behaviour of gas and stars in these two kinds of objects. Namely, whereas in X-ray bright and slowly rotating galaxies stellar-loss material would quickly evaporate in the hot medium, in X-ray faint and fast rotating objects such material would be allowed to lose angular momentum and settle in a disk, which could also obstruct the subsequent acquisition of retrograde gas. Evidence for a connection between warm and hot gas phases, presumably driven by heat conduction, is presented for four slowly rotating galaxies with Chandra observations. (c) 2006 Elsevier B.V. All rights reserved.