The kinematic imprinting of environmental quenching in $z<0.2$ galaxies

Abstract

We present the first systematic census of quenching mechanisms using kinematic asymmetries in a large sample of $\sim$6,700 galaxies from the MaNGA survey, providing a unified view of what halts star formation in the local Universe ($z<0.2$). We quantify stellar and nebular gas disturbances through the higher-order terms of a Fourier series expansion. These asymmetries serve as powerful diagnostics, as different quenching mechanisms leave distinct kinematic signatures on gas and stars. Our analysis reveals that the most effective quenching pathways leave minimal kinematic imprints by the time galaxies are fully quenched. This "kinematic regularity" points toward slow-acting processes (>3 Gyr) such as starvation and maintenance feedback. A striking finding emerges from our mass-matched analysis: quenched symmetric satellites are significantly more compact than their asymmetric counterparts ($3.4σ$), a trend that is even more pronounced for symmetric centrals ($12.3σ$). Our results suggest that environment drives the dominant satellite quenching pathway through rapid gas stripping followed by long-term starvation. These compact, kinematically undisturbed satellites (the most representative case within our sample) have undergone intense gas stripping and central compaction, creating bulge-like structures with old, metal-rich stellar populations. Combined with halo gas cut-off and the prevention of cosmological accretion due to starvation, this creates an irreversible quenching path. Conversely, the larger sizes of disturbed, quenched centrals are consistent with merger-driven growth. Internal processes, likely driven by the AGN cycle over 1-3 Gyr that prevents hot halo gas cooling, sustain quenching maintenance in this population. The absence of asymmetric satellites in the star-forming regime suggests environmental quenching operates without significant kinematic perturbation.

Figures (13)

• Figure 1: Distribution of our sample of galaxies in the SFR-M$_\star$ plane, colour-coded by the fraction of satellites. As expected, the highest satellite fractions are found among quiescent galaxies with M$_\star \lesssim 10^{10.5}$ M$_\odot$, a region we refer to as the 'satellite region'. The lines indicate the boundaries separating star forming, green valley, and quiescent galaxies as presented in Behroozi+19.
• Figure 2: Left panel: Stellar mass distribution of our MaNGA sample including both central and satellite galaxies. Middle panel: Halo mass distribution of our sample separated by centrals or satellites. Right panel: Fraction of centrals/satellites per stellar mass bin. In all panels, we show the representativeness of our sample by comparing it to SDSS spectroscopic sample complete in stellar mass down to 10$^{10}~M_\odot$ at $z\sim0.085$.
• Figure 3: SFR–$M_\star$ plane of our galaxy sample, colour-coded by the signal-to-noise ratio of each individual object. The top panel shows our subsample with reliable stellar velocity maps (i.e., maps with $\geq$90% valid spaxels within 1$R_{\rm eff}$). The bottom panel shows galaxies with reliable gaseous velocity maps. The lines indicate the boundaries separating star-forming, green valley, and quiescent galaxies as defined in Behroozi+19.
• Figure 4: Top panel: distribution of galaxies with Kinemetry info on the stellar component in the SFR-M$_\star$ plane, colour-coded by the average asymmetry parameter of the stellar kinematic map. As in Fig. \ref{['fig:3plots']}, the lines indicate the boundaries separating star forming, green valley, and quiescent galaxies as present in Behroozi+19. The upper curves indicate the PDF of galaxies classified as asymmetric according to different Kinemetry thresholds in $I_{\text{asym}}$. Bottom panel: As in the upper panel, now for galaxies with Kinemetry info on the gaseous component.
• Figure 5: We show in panel a the sSFR-M$_\star$ plane displaying all symmetric galaxies ($I_{asym}=0.05$) in our sample, including both centrals and satellites. Subsequent panels highlight galaxies with kinematic asymmetries in the stellar component (panel b), and gaseous component (panel c). Panel d displays galaxies with asymmetries in both maps, followed by galaxies with asymmetries solely in stars (panel e) and gas (panel f). To guide the eye, we show the corresponding PDFs in the lower left corner of each panel. We also show a dashed red line separating quiescent and star-forming galaxies. Following our selection criteria, only galaxies with at least 90% of valid spaxels (spaxels with SNR$_{\star,\rm gas}>5$) are included. The absence of asymmetric galaxies in the so-called 'satellite region' of the (s)SFR–$M_\star$ plane (see also Fig. \ref{['fig:satellite_fraction']}) strongly suggests that the mechanism suppressing star formation in our sample does not significantly impact the kinematic structure of the galaxy.