Galaxy zoo: The fundamentally different co-evolution of supermassive black holes and their early- and late-type host galaxies
Astrophysical Journal 711:1 (2010) 284-302
Abstract:
We use data from the Sloan Digital Sky Survey and visual classifications of morphology from the Galaxy Zoo project to study black hole growth in the nearby universe (z < 0.05) and to break down the active galactic nucleus (AGN) host galaxy population by color, stellar mass, and morphology. We find that the black hole growth at luminosities >1040erg s-1 in early- and late-type galaxies is fundamentally different. AGN host galaxies as a population have a broad range of stellar masses (1010-10 11M ⊙), reside in the green valley of the color-mass diagram and their central black holes have median masses around 10 6.5M ⊙. However, by comparing early- and late-type AGN host galaxies to their non-active counterparts, we find several key differences: in early-type galaxies, it is preferentially the galaxies with the least massive black holes that are growing, while in late-type galaxies, it is preferentially the most massive black holes that are growing. The duty cycle of AGNs in early-type galaxies is strongly peaked in the green valley below the low-mass end (1010M ⊙) of the red sequence at stellar masses where there is a steady supply of blue cloud progenitors. The duty cycle of AGNs in late-type galaxies on the other hand peaks in massive (10 11M ⊙) green and red late-types which generally do not have a corresponding blue cloud population of similar mass. At high-Eddington ratios (L/L Edd>0.1), the only population with a substantial fraction of AGNs are the low-mass green valley early-type galaxies. Finally, the Milky Way likely resides in the "sweet spot" on the color-mass diagram where the AGN duty cycle of late-type galaxies is highest. We discuss the implications of these results for our understanding of the role of AGNs in the evolution of galaxies. © 2010 The American Astronomical Society.Tasking Citizen Scientists from Galaxy Zoo to Model Galaxy Collisions
GALAXY WARS: STELLAR POPULATIONS AND STAR FORMATION IN INTERACTING GALAXIES 423 (2010) 217-+
Tasking Citizen Scientists from Galaxy Zoo to Model Galaxy Collisions: Preliminary Results, Interface, Analysis
GALAXY WARS: STELLAR POPULATIONS AND STAR FORMATION IN INTERACTING GALAXIES 423 (2010) 223-+
Galaxy Zoo: Exploring the Motivations of Citizen Science Volunteers
ArXiv 0909.2925 (2009)
Abstract:
The Galaxy Zoo citizen science website invites anyone with an Internet connection to participate in research by classifying galaxies from the Sloan Digital Sky Survey. As of April 2009, more than 200,000 volunteers had made more than 100 million galaxy classifications. In this paper, we present results of a pilot study into the motivations and demographics of Galaxy Zoo volunteers, and define a technique to determine motivations from free responses that can be used in larger multiple-choice surveys with similar populations. Our categories form the basis for a future survey, with the goal of determining the prevalence of each motivation.Galaxy Zoo Green Peas: Discovery of A Class of Compact Extremely Star-Forming Galaxies
ArXiv 0907.4155 (2009)