3,310 research outputs found
Reddening Behaviors of Galaxies in the SDSS Photometric System
We analyze the behaviors of reddening vectors in the SDSS photometric system
for galaxies of different morphologies, ages, and redshifts. As seen in other
photometric systems, the dependence of reddening on the spectral energy
distribution (SED) and the nonlinearity of reddening are likewise
non-negligible for the SDSS system if extinction is significant (~> 1 mag).
These behaviors are most significant for the g filter, which has the largest
bandwidth-to-central wavelength ratio among SDSS filters. The SDSS colors
involving adjacent filters show greater SED-dependence and nonlinearity. A
procedure for calculating the correct amount of extinction from an observed
color excess is provided. The relative extinctions between (i.e., the
extinction law for) SDSS filters given by Schlegel et al., which were
calculated with an older version of filter response functions, would
underestimate the amount of extinction in most cases by ~5 to 10 % (maximum ~20
%). We recommend A/A_{5500} values of 1.574, 1.191, 0.876, 0.671 & 0.486 for
the u, g, r, i, & z filters, respectively, as a representative extinction law
for the SDSS galaxies with a small extinction (i.e., for cases where the
nonlinearity and SED-dependence of the reddening is not important). The
dependence of reddening on redshift at low extinction is the largest for colors
involving the g filter as well, which is due to the Balmer break.Comment: Published in PASP, 119, 1449 (Dec. 2007
Phase transition between non-extremal and extremal Reissner-Nordstr\"om black holes
We discuss the phase transition between non-extremal and extremal
Reissner-Nordstr\"om black holes. This transition is considered as the
limit of the transition between the non-extremal and near-extremal
black holes.
We show that an evaporating process from non-extremal black hole to extremal
one is possible to occur, but its reverse process is not possible to occur
because of the presence of the maximum temperature.
Furthermore, it is shown that the Hawking-Page phase transition between small
and large black holes unlikely occurs in the AdS Reissner-Nordstr\"om black
holes.Comment: 12 pages, 6 figures, version to appear in MPL
- β¦