Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Revisiting the Galactic Winds in M82 I: the recent starburst and launch of outflow in simulations

Tian-Rui Wang, Weishan Zhu, Xue-Fu Li, Wen-Sheng Hong, Long-Long Feng

TL;DR

This paper develops a self-consistent, sink-particle–driven framework to resolve the recent nuclear starburst and the launch of a galactic-scale wind in M82, incorporating radiation, stellar winds, and core-collapse SNe within a realistic mass model and cooling/heating physics.The simulations reveal a two-stage wind: an initial superbubble breakout in the central disk followed by a kiloparsec-scale multiphase outflow where cool filaments largely originate from pre-existing disk structures and are entrained by the hot wind.While the mass loading factors align with observations, the simulated cool gas velocities and some outflow rates are systematically lower than those inferred for M82, indicating that enhanced feedback efficiency from clustered SNe may be required to fully reproduce the observed winds.Overall, the work underscores the importance of self-consistent star formation and feedback modeling for understanding galactic winds and sets the stage for further exploration of clustered SN effects and higher-resolution studies.

Abstract

We revisit the launch of the galactic outflow in M82 using hydrodynamic simulations. Employing a sink-particle module, we self-consistently resolve star formation and feedback, avoiding reliance on simplified models. We investigate the effects of stellar feedback mechanisms, gas return from star-forming clouds, and disk mass on the starburst and outflow. Our simulations generate a starburst lasting $\sim25$ Myr, peaking at 20-50 $\rm{M_{\odot},yr^{-1}}$, although the total stellar mass often exceeds M82's estimated value. The outflow develops in two stages: initially, continuous SNe form small bubbles that merge into a superbubble containing warm/hot gas and intermediate- to high-density cool filaments. After $\sim10$ Myr, the superbubble breaks out of the disk, and within $\sim15$ Myr a kpc-scale outflow forms. Cool filaments survive stellar feedback, become entrained in the wind, and stretch to hundreds of parsecs. Transport from the cool ISM is the dominant net contributor to the total mass of the cool phase in the outflow, whereas transfers from hotter phases, such as through condensation or precipitation, provide only a minor net contribution, likely offset by simultaneous transfer from the cool phase back to hotter phases. While the mass loading factor is comparable to M82, the cool gas outflow rate and velocity are lower, with velocities $\sim60\%$ below observed values; warm and hot gas are $\sim25\%$ slower. SN feedback is the primary driver, and gas return significantly influences the starburst and outflow, while other factors are secondary. Stronger clustered SN feedback is likely required to better match observations.

Revisiting the Galactic Winds in M82 I: the recent starburst and launch of outflow in simulations

TL;DR

This paper develops a self-consistent, sink-particle–driven framework to resolve the recent nuclear starburst and the launch of a galactic-scale wind in M82, incorporating radiation, stellar winds, and core-collapse SNe within a realistic mass model and cooling/heating physics.The simulations reveal a two-stage wind: an initial superbubble breakout in the central disk followed by a kiloparsec-scale multiphase outflow where cool filaments largely originate from pre-existing disk structures and are entrained by the hot wind.While the mass loading factors align with observations, the simulated cool gas velocities and some outflow rates are systematically lower than those inferred for M82, indicating that enhanced feedback efficiency from clustered SNe may be required to fully reproduce the observed winds.Overall, the work underscores the importance of self-consistent star formation and feedback modeling for understanding galactic winds and sets the stage for further exploration of clustered SN effects and higher-resolution studies.

Abstract

We revisit the launch of the galactic outflow in M82 using hydrodynamic simulations. Employing a sink-particle module, we self-consistently resolve star formation and feedback, avoiding reliance on simplified models. We investigate the effects of stellar feedback mechanisms, gas return from star-forming clouds, and disk mass on the starburst and outflow. Our simulations generate a starburst lasting Myr, peaking at 20-50 , although the total stellar mass often exceeds M82's estimated value. The outflow develops in two stages: initially, continuous SNe form small bubbles that merge into a superbubble containing warm/hot gas and intermediate- to high-density cool filaments. After Myr, the superbubble breaks out of the disk, and within Myr a kpc-scale outflow forms. Cool filaments survive stellar feedback, become entrained in the wind, and stretch to hundreds of parsecs. Transport from the cool ISM is the dominant net contributor to the total mass of the cool phase in the outflow, whereas transfers from hotter phases, such as through condensation or precipitation, provide only a minor net contribution, likely offset by simultaneous transfer from the cool phase back to hotter phases. While the mass loading factor is comparable to M82, the cool gas outflow rate and velocity are lower, with velocities below observed values; warm and hot gas are slower. SN feedback is the primary driver, and gas return significantly influences the starburst and outflow, while other factors are secondary. Stronger clustered SN feedback is likely required to better match observations.

Paper Structure

This paper contains 35 sections, 34 equations, 22 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Method
  3. Mass model of M82
  4. Initial conditions in simulation
  5. Star formation
  6. Jean's instability
  7. Distance check
  8. Convergent flow
  9. Gravitational potential minimum
  10. Gas accretion and star formation
  11. Feedback
  12. Gas return from sink particle
  13. Radiation
  14. Stellar Wind
  15. Core-collapse SNe
  16. ...and 20 more sections

Figures (22)

  • Figure 1: Observation results of the rotation curve provided by 2012ApJ...757...24G(red and yellow dots) and our model (blue solid line). The rotation curve contributed by the different components is shown as dashed lines.
  • Figure 2: Face-on view of the gas disk in the FD simulation, showing the projected gas density overlaid with star particles (white dots). This picture shows star particles form predominantly within high-density clumps. The bottom panels illustrate how superbubbles develop around clustered star particles. In these panels, the large number of star particles partly obscures the underlying high-density clumps.
  • Figure 3: Top: The star formation rate as a function of time in various simulations. Middle: The cumulative mass of stars formed since the beginning of the simulation. Bottom: The remaining stellar mass within $r<1000$ pc that has yet undergone SNe as a function of time.
  • Figure 4: The surface star formation rate density against the surface gas density in the FD (filled blue circle), fSN (filled yellow circle) and nSN (filled green circle) simulations, compared to the to the Kennicutt-Schmidt law (solid blue line), starburst galaxies and spiral galaxies in 1998ApJ...498..541K. For clarity, the fSN and nSN data points have been shifted upward by 0.5 and 1.0 dex, respectively.
  • Figure 5: Top: the cumulative star cluster mass function in various simulations. Middle: the distribution of integrated star formation efficiency in sink/star particles. Bottom: The distribution of stellar metallicity in various simulations. The metallicity in nFB and nSN are $0.02\rm{Z_{\odot}}$, which has been shifted leftward slightly in the plot for the sake of clarity.
  • ...and 17 more figures