= Solution
Stellar <radiation>, <stellar winds> and <supernovae> return <energy>, <momentum>, <mass> and metals to surrounding gas. Heating, <ionization>, turbulent support and gas removal can reduce subsequent <star formation>; swept-up shells can also compress gas locally. Whether thermal <energy> drives an outflow depends on its <radiative gas cooling time> relative to expansion: radiative losses can remove <energy> while leaving substantial <momentum> transfer. Thus deposited <energy> alone does not specify the dynamical effect.
The <galactic gas regulator> has <mass> budget $\dot M_g=\dot M_{\rm in}-(1-R+\eta)\Psi$, where $R$ is the returned fraction and $\eta=\dot M_{\rm out}/\Psi$ is the <mass-loading factor>. In a quasi-steady state, $\Psi\simeq\dot M_{\rm in}/(1-R+\eta)$. This connects feedback to the available gas supply. A wind's kinetic power $\dot M_{\rm out}v_w^2/2$ and <momentum> flux $\dot M_{\rm out}v_w$ must fit the source budget and gravitational binding cost. Gas that fails to escape may form a <galactic fountain> and later return; preferential metal loss changes chemical evolution.
Absorption against a galaxy's stellar continuum provides a concrete outflow test: compare interstellar sodium absorption with the systemic velocity and stellar absorption spectrum. A primary starburst survey found blueshifted interstellar absorption and an inclination dependence consistent with minor-axis outflows. Its saturated lines also illustrate why velocity detection is more direct than a unique column <density> or <mass> flux.<Absorption-Line Probes of Gas and Dust in Galactic Superwinds by Timothy M. Heckman and others>[Abstract: NaD spectra, systemic velocities, viewing angle and optical depth]{ref} Deprojection, covering fraction, <ionization>, radius and the unseen hot phase limit total outflow-rate estimates.
An accreting <supermassive black hole> adds <radiation>, winds and <astrophysical jets>. Coupling these to the interstellar or <circumgalactic medium> can suppress cooling or expel gas, especially in deep potentials where stellar driving alone may be inadequate. Jet cavities, line-emitting gas and multiphase outflows test different channels; coexisting activity and low <star formation> alone do not prove a causal feedback history.
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