Spatially resolved galactic wind in lensed galaxy RCSGA 032727-132609

Abstract

We probe the spatial distribution of outflowing gas along four lines of sight separated by up to 6 kpc in a gravitationally-lensed star-forming galaxy at z = 1.70. Using Mg ii and Fe ii emission and absorption as tracers, we find that the clumps of star formation are driving galactic outflows with velocities of -170 to -250 km/sec. The velocities of Mg ii emission are redshifted with respect to the systemic velocities of the galaxy, consistent with being backscattered. By contrast, the Fe ii fluorescent emission lines are either slightly blueshifted or at the systemic velocity of the galaxy. Taken together, the velocity structure of the Mg ii and Fe ii emission is consistent with arising through scattering in galactic winds. Assuming a thin shell geometry for the outflowing gas, the estimated masses carried out by these outflows are large ( 30 -50 M yr −1 ), with mass loading factors several times the star-formation rate. Almost 20% to 50% of the blueshifted absorption probably escapes the gravitational potential of the galaxy. In this galaxy, the outflow is "locally sourced", that is, the properties of the outflow in each line of sight are dominated by the properties of the nearest clump of star formation; the wind is not global to the galaxy. The mass outflow rates and the momentum flux carried out by outflows in individual star forming knots of this object are comparable to that of starburst galaxies in the local Universe.

The Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas (MegaSaura). II. Stacked Spectra

“…In the MegaSaura weighted-average shapenormalized stack, these transitions have a maximum velocity of |v max |= 900 km s −1 (Table 1.) Bordoloi et al (2016) analyzed the velocity profiles of four regions within one of these galaxies, RCS-GA 032727−132609, and found 95th percentile velocities of 460-610 km s −1 for these transitions. Mg II is at the extreme red end of the MegaSaura stack, and so only four galaxy spectra went into the stack; seven galaxies contribute to the stack for Fe II 2344 and Fe II 2383.…”

C Iii] Emission in Star-Forming Galaxies Near and Far

“…Columns: (1) source name; (2) redshift; (3) 12 log O H ( ) + metallicity; (4) reference; (5) rest-frame Lyα equivalent width; (6) uncertainty; (7) reference; (8) rest-frame C III] equivalent width, sum of both transitions when resolved; (9) uncertainty; (10) reference; (11) sample; (12) magnitude for MagE sample; (13) reference. Redshifts for MagE galaxies are from Bordoloi et al (2015) for RCS0327, else from Rigby et al (2014) and in preparation. Redshifts for z ∼ 0 galaxies are from NED.…”

A hydrodynamical study of outflows in starburst galaxies with different driving mechanisms

“…Galactic outflows are a multi-phase, multi-component media (see Ohyama et al 2002;Strickland et al 2002;Melioli et al 2013;Martín-Fernández et al 2016), comprised of cool semi-ionised clumps of gas (of temperature T c ∼ 10 2 − 10 4 K -see Strickland et al 1997;Lehnert et al 1999) entrained within a hot (T h ∼ 10 7 K McKeith et al 1995;Shopbell & Bland-Hawthorn 1998), low-density X-ray emitting fluid which may extend to altitudes of several kpc (Strickland et al 2000;Cecil et al 2002b;Cecil et al 2002a). Above this, there is a cap (in M82, this is observed at 11.6 kpcsee Devine & Bally 1999;Tsuru et al 2007), with the full outflow structure extending to tens of kpc (see Veilleux et al 2005;Bland-Hawthorn et al 2007;Bordoloi et al 2011;Martin et al 2013;Rubin et al 2014;Bordoloi et al 2016). In the hot fluid region of an outflow, cooling processes are presumably important and would have a significant impact on the dynamics and evolution of the flow (Heckman 2003).…”