Galaxy Zoo: Observing Secular Evolution Through Bars by Cheung, E, Athanassoula, E, Masters, K, Nichol, R, Bosma, A, Bell, E, Faber, S, Koo, D, Lintott, C, Melvin, T, Schawinski, K, Skibba, R, Willett, K

“…These results represent empirical evidence for secular evolution driven by bars in disk galaxies. …”

Galaxy Zoo: Secular evolution of barred galaxies from structural decomposition of multi-band images by Kruk, S, Lintott, C, Bamford, S, Masters, K, Simmons, B, Häußler, B, Cardamone, C, Hart, R, Kelvin, L, Schawinski, K, Smethurst, R, Vika, M

“…We find possible evidence of secular evolution via bars that leads to the build-up of pseudobulges and to the quenching of star formation in the discs. …”

Galaxy Zoo: Bulgeless Galaxies With Growing Black Holes by Simmons, B, Lintott, C, Schawinski, K, Moran, E, Han, A, Kaviraj, S, Masters, K, Urry, C, Willett, K, Bamford, S, Nichol, R

“…The growth of supermassive black holes appears to be driven by galaxy mergers, violent merger-free processes and/or `secular' processes. In order to quantify the effects of secular evolution on black hole growth, we study a sample of active galactic nuclei (AGN) in galaxies with a calm formation history free of significant mergers, a population that heretofore has been difficult to locate. …”

Galaxy Zoo: Evidence for rapid, recent quenching within a population of AGN host galaxies by Smethurst, R, Lintott, C, Simmons, B, Schawinski, K, Bamford, S, Cardamone, C, Kruk, S, Masters, K, Urry, C, Willett, K, Wong, O

“…We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. …”

Galaxy Zoo: Bars in Disk Galaxies by Masters, K, Nichol, R, Hoyle, B, Lintott, C, Bamford, S, Edmondson, E, Fortson, L, Keel, W, Schawinski, K, Smith, A, Thomas, D

“…We discuss these results in the context of internal (secular) galaxy evolution scenarios and the possible links to the formation of bars and bulges in disk galaxies.…”

Type 2 AGN host galaxies in the Chandra-COSMOS legacy survey: No evidence of AGN-driven quenching by Suh, H, Civano, F, Hasinger, G, Lusso, E, Lanzuisi, G, Marchesi, S, Trakhtenbrot, B, Allevato, V, Cappelluti, N, Capak, P, Elvis, M, Griffiths, R, Laigle, C, Lira, P, Riguccini, L, Rosario, D, Salvato, M, Schawinski, K, Vignali, C

“…This could be interpreted in a scenario, where the relative massive galaxies have already experienced substantial growth at higher redshift (z > 3), and grow slowly through secular fueling processes hosting moderate-luminosity AGNs.…”

Galaxy Zoo and ALFALFA: Atomic Gas and the Regulation of Star Formation in Barred Disc Galaxies by Masters, K, Nichol, R, Haynes, M, Keel, W, Lintott, C, Simmons, B, Skibba, R, Bamford, S, Giovanelli, R, Schawinski, K

“…In addition our observations suggest bars may reduce or halt star formation in the outer parts of discs by holding back the infall of external gas beyond bar co-rotation, reddening the global colours of barred disc galaxies. This suggests that secular evolution driven by the exchange of angular momentum between stars in the bar, and gas in the disc, acts as a feedback mechanism to regulate star formation in intermediate mass disc galaxies.…”

The Green Valley is a Red Herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early- and late-type galaxies by Schawinski, K, Urry, C, Simmons, B, Fortson, L, Kaviraj, S, Keel, W, Lintott, C, Masters, K, Nichol, R, Sarzi, M, Ramin, Skibba, Treister, E, Willett, K, Wong, O, Yi, S

“…We conclude that late-type galaxies are consistent with a scenario where the cosmic supply of gas is shut off, perhaps at a critical halo mass, followed by a slow exhaustion of the remaining gas over several Gyr, driven by secular and/or environmental processes. In contrast, early-type galaxies require a scenario where the gas supply and gas reservoir are destroyed virtually instantaneously, with rapid quenching accompanied by a morphological transformation from disk to spheroid. …”

Galaxy Zoo: An independent look at the evolution of the bar fraction over the last eight billion years from HST-COSMOS by Melvin, T, Masters, K, Lintott, C, Nichol, R, Simmons, B, Bamford, S, Casteels, K, Cheung, E, Edmondson, E, Fortson, L, Schawinski, K, Skibba, R, Smith, A, Willett, K

“…Our results are consistent with a picture in which the evolution of massive disc galaxies begins to be affected by slow (secular) internal process at z~1. We discuss possible connections of the decrease in bar fraction to the redshift, including the growth of stable disc galaxies, mass evolution of the gas content in disc galaxies, as well as the mass dependent effects of tidal interactions.…”