Quenching in the Right Place at the Right Time: Tracing the Shared History of Starbursts, AGNs, and Post-starburst Galaxies Using Their Structures and Multiscale Environments

Abstract: This work uses multiscale environments and structures of galaxies in the Sloan Digital Sky Survey as consistency checks of the evolution from starburst to quiescence at redshift $z < 0.2$. The environmental indicators include fixed aperture mass overdensities ($\delta_{x\mathrm{Mpc}}$, $x \in {0.5, 1, 2, 4, 8}\,h^{-1}$Mpc), $k$-nearest neighbor distances, the tidal parameter, halo mass ($M_h$), and satellite/central classification. The residuals of specific star formation rates ($\Delta\,\mathrm{SSFR}$) is used to select starbursts ($\Delta\,\mathrm{SSFR} > 0.6\,$dex, $N \approx 8,\,600$). Quenched post-starbursts (QPSBs) are selected using H$\alpha < 3\,$angstrom in emission and H$\delta_A > 4\,$ angstrom in absorption ($N \approx 750$). The environments of starbursts and QPSBs are compared with those of active galactic nuclei (AGNs) and inactive galaxies of varying $\Delta\,\mathrm{SSFR}$. The environments of starbursts, AGNs, and QPSBs are unlike the environments of most quiescent galaxies (QGs). About $70\%-90\%$ of starbursts, AGNs with H$\delta_A > 4$, and QPSBs are centrals, $\sim 80\%-90\%$ have $M_h < 10^{13}\,M_\odot$, and only $\sim 2\%-4\%$ have $M_h > 10^{14}\,M_\odot$ or live in clusters. Their $M_h$ and satellite fractions are also different from those of QGs. All QPSBs are matched to some SFGs, starbursts, AGNs, and QGs of similar $M_\star$, environments, concentration indices, and velocity dispersions. A significant fraction ($\sim 20\%-30\%$) of starbursts cannot be matched to QPSBs or QGs. The implications are: (1) some starbursts do not quench rapidly. (2) Satellite-quenching mechanisms operating in high density environments cannot account for most QPSBs. (3) The evolution from starbursts to QPSBs to QGs is not the dominant path at $z < 0.2$. (4) Starbursts are not mainly triggered by tidal interactions.