We study star formation-driven outflows in a z ∼ 0.02 starbursting disc galaxy, IRAS08339+6517, using spatially resolved measurements from the Keck Cosmic Web Imager (KCWI). We develop a new method incorporating a multistep process to determine whether an outflow should be fit in each spaxel, and then subsequently decompose the emission line into multiple components. We detect outflows ranging in velocity, vout, from 100 to 600 km s−1 across a range of star formation rate surface densities, ΣSFR, from ∼0.01 to 10 M⊙ yr−1 kpc−2 in resolution elements of a few hundred parsec. Outflows are detected in ∼100 per cent of all spaxels within the half-light radius, and ∼70 per cent within r90, suggestive of a high covering fraction for this starbursting disc galaxy. Around 2/3 of the total outflowing mass originates from the star forming ring, which corresponds to ${\lt}10{{\ \rm per\ cent}}$ of the total area of the galaxy. We find that the relationship between vout and the ΣSFR, as well as between the mass loading factor, η, and the ΣSFR, are consistent with trends expected from energy-driven feedback models. We study the resolution effects on this relationship and find stronger correlations above a re-binned size-scale of ∼500 pc. Conversely, we do not find statistically significant consistencymore »
- Award ID(s):
- 1907790
- Publication Date:
- NSF-PAR ID:
- 10376597
- Journal Name:
- The Astrophysical Journal
- Volume:
- 928
- Issue:
- 1
- Page Range or eLocation-ID:
- 54
- ISSN:
- 0004-637X
- Sponsoring Org:
- National Science Foundation
More Like this
-
ABSTRACT -
Abstract Physical and chemical properties of the interstellar medium (ISM) at subgalactic (∼kiloparsec) scales play an indispensable role in controlling the ability of gas to form stars. In this paper, we use the TNG50 cosmological simulation to explore the physical parameter space of eight resolved ISM properties in star-forming regions to constrain the areas of this hyperspace where most star-forming environments exist. We deconstruct our simulated galaxies spanning a wide range of mass ( M ⋆ = 10 7 –10 11 M ⊙ ) and redshift (0 ≤ z ≤ 3) into kiloparsec-sized regions and statistically analyze the gas/stellar surface densities, gas metallicity, vertical stellar velocity dispersion, epicyclic frequency, and dark-matter volumetric density representative of each region in the context of their star formation activity and environment (radial galactocentric location). By examining the star formation rate (SFR) weighted distributions of these properties, we show that stars primarily form in two distinct environmental regimes, which are brought about by an underlying bicomponent radial SFR profile in galaxies. We examine how the relative prominence of these regimes depends on galaxy mass and cosmic time. We also compare our findings with those from integral field spectroscopy observations and find similarities as well asmore »
-
ABSTRACT We use analytical calculations and time-dependent spherically symmetric simulations to study the properties of isothermal galactic winds driven by cosmic rays (CRs) streaming at the Alfvén velocity. The simulations produce time-dependent flows permeated by strong shocks; we identify a new linear instability of sound waves that sources these shocks. The shocks substantially modify the wind dynamics, invalidating previous steady state models: the CR pressure pc has a staircase-like structure with dpc/dr ≃ 0 in most of the volume, and the time-averaged CR energetics are in many cases better approximated by pc ∝ ρ1/2, rather than the canonical pc ∝ ρ2/3. Accounting for this change in CR energetics, we analytically derive new expressions for the mass-loss rate, momentum flux, wind speed, and wind kinetic power in galactic winds driven by CR streaming. We show that streaming CRs are ineffective at directly driving cold gas out of galaxies, though CR-driven winds in hotter ISM phases may entrain cool gas. For the same physical conditions, diffusive CR transport (Paper I) yields mass-loss rates that are a few-100 times larger than streaming transport, and asymptotic wind powers that are a factor of ≃4 larger. We discuss the implications of our results for galactic wind theory and observations; strongmore »
-
ABSTRACT Advances in instrumentation have recently extended detailed measurements of gas kinematics to large samples of high-redshift galaxies. Relative to most nearby, thin disc galaxies, in which gas rotation accurately traces the gravitational potential, the interstellar medium (ISM) of $z$ ≳ 1 galaxies is typically more dynamic and exhibits elevated turbulence. If not properly modelled, these effects can strongly bias dynamical mass measurements. We use high-resolution FIRE-2 cosmological zoom-in simulations to analyse the physical effects that must be considered to correctly infer dynamical masses from gas kinematics. Our analysis covers a range of galaxy properties from low-redshift Milky-Way-mass galaxies to massive high-redshift galaxies (M⋆ > 1011 M⊙ at $z$ = 1). Selecting only snapshots where a disc is present, we calculate the rotational profile $\bar{v}_\phi (r)$ of the cool ($10^{3.5}\,\lt {\it T}\lt 10^{4.5}~\rm {K}$) gas and compare it to the circular velocity $v_{\rm c}=\sqrt{GM_{\rm enc}/r}$. In the simulated galaxies, the gas rotation traces the circular velocity at intermediate radii, but the two quantities diverge significantly in the centre and in the outer disc. Our simulations appear to over-predict observed rotational velocities in the centres of massive galaxies (likely from a lack of black hole feedback), so we focus on largermore »
-
Context. Supersonic disordered flows accompany the formation and evolution of molecular clouds (MCs). It has been argued that this is turbulence that can support against gravitational collapse and form hierarchical sub-structures. Aims. We examine the time evolution of simulated MCs to investigate: What physical process dominates the driving of turbulent flows? How can these flows be characterised? Are they consistent with uniform turbulence or gravitational collapse? Do the simulated flows agree with observations? Methods. We analysed three MCs that have formed self-consistently within kiloparsec-scale numerical simulations of the interstellar medium (ISM). The simulated ISM evolves under the influence of physical processes including self-gravity, stratification, magnetic fields, supernova-driven turbulence, and radiative heating and cooling. We characterise the flows using velocity structure functions (VSFs) with and without density weighting or a density cutoff, and computed in one or three dimensions. However, we do not include optical depth effects that can hide motions in the densest gas, limiting comparison of our results with observations. Results. In regions with sufficient resolution, the density-weighted VSFs initially appear to follow the expectations for uniform turbulence, with a first-order power-law exponent consistent with Larson’s size-velocity relationship. Supernova blast wave impacts on MCs produce short-lived coherent motions atmore »