TY - CHAP
T1 - Deprojecting the Quenching of Star Formation in and Near Clusters
AU - Mamon, GA
AU - Mahajan, S
AU - Raychaudhury, Somak
PY - 2011/1/1
Y1 - 2011/1/1
N2 - Using Hδ and D n 4000 as tracers of recent
or ongoing efficient star formation, we analyze the fraction of SDSS
galaxies with recent or ongoing efficient star formation (GORES) in the
vicinity of 268 clusters. We confirm the well-known segregation of star
formation, and using Abel deprojection, we find that the fraction of
GORES increases linearly with physical radius and then saturates.
Moreover, we find that the fraction of GORES is modulated by the
absolute line-of-sight velocity (ALOSV): at all projected radii, higher
fractions of GORES are found in higher ALOSV galaxies. We model this
velocity modulation of GORES fraction using the particles in a
hydrodynamical cosmological simulation, which we classify into
virialized, infalling and backsplash according to their position in
radial phase space at z = 0. Our simplest model, where the GORES
fraction is only a function of class does not produce an adequate fit to
our observed GORES fraction in projected phase space. On the other hand,
assuming that in each class the fraction of GORES rises linearly and
then saturates, we are able to find well-fitting 3D models of the
fractions of GORES. In our best-fitting models, in comparison with 18%
in the virial cone and 13% in the virial sphere, GORES respectively
account for 34% and 19% of the infalling and backsplash galaxies, and as
much as 11% of the virialized galaxies, possibly as a result of tidally
induced star formation from galaxy-galaxy interactions. At the virial
radius, the fraction of GORES of the backsplash population is much
closer to that of the virialized population than to that of the
infalling galaxies. This suggests that the quenching of efficient star
formation is nearly complete in a single passage through the cluster.
AB - Using Hδ and D n 4000 as tracers of recent
or ongoing efficient star formation, we analyze the fraction of SDSS
galaxies with recent or ongoing efficient star formation (GORES) in the
vicinity of 268 clusters. We confirm the well-known segregation of star
formation, and using Abel deprojection, we find that the fraction of
GORES increases linearly with physical radius and then saturates.
Moreover, we find that the fraction of GORES is modulated by the
absolute line-of-sight velocity (ALOSV): at all projected radii, higher
fractions of GORES are found in higher ALOSV galaxies. We model this
velocity modulation of GORES fraction using the particles in a
hydrodynamical cosmological simulation, which we classify into
virialized, infalling and backsplash according to their position in
radial phase space at z = 0. Our simplest model, where the GORES
fraction is only a function of class does not produce an adequate fit to
our observed GORES fraction in projected phase space. On the other hand,
assuming that in each class the fraction of GORES rises linearly and
then saturates, we are able to find well-fitting 3D models of the
fractions of GORES. In our best-fitting models, in comparison with 18%
in the virial cone and 13% in the virial sphere, GORES respectively
account for 34% and 19% of the infalling and backsplash galaxies, and as
much as 11% of the virialized galaxies, possibly as a result of tidally
induced star formation from galaxy-galaxy interactions. At the virial
radius, the fraction of GORES of the backsplash population is much
closer to that of the virialized population than to that of the
infalling galaxies. This suggests that the quenching of efficient star
formation is nearly complete in a single passage through the cluster.
U2 - 10.1007/978-3-642-20285-8_27
DO - 10.1007/978-3-642-20285-8_27
M3 - Chapter
T3 - Astrophysics and Space Science Proceedings
BT - Environment and the Formation of Galaxies: 30 years later
ER -