Theoretical Isochrones with Extinction in the K Band. II. J - K versus K

We calculate theoretical isochrones in a consistent way for five filter pairs near the J and K band atmospheric windows (J-K, J-K', J-Ks, F110W-F205W, and F110W-F222M) using the Padova stellar evolutionary models of Girardi et al. We present magnitude transformations between various K-band filters as a function of color. Isochrones with extinction of up to 6 mag in the K band are also presented. As found for the filter pairs composed of H & K band filters, we find that the reddened isochrones of different filter pairs behave as if they follow different extinction laws, and that the extinction curves of Hubble Space Telescope NICMOS filter pairs in the color-magnitude diagram are considerably nonlinear. Because of these problems, extinction values estimated with NICMOS filters can be in error by up to 1.3 mag. Our calculation suggests that the extinction law implied by the observations of Rieke et al for wavelengths between the J and K bands is better described by a power-law function with an exponent of 1.66 instead of 1.59, which is commonly used with an assumption that the transmission functions of J and K filters are Dirac delta functions.Comment: Published in PASP, 118, 62 (Jan. 2006

The Globular Cluster Systems of Five Nearby Spiral Galaxies: New Insights from Hubble Space Telescope Imaging

We use available multifilter Hubble Space Telescope (HST) WFPC2 imaging of five (M81, M83, NGC 6946, M101, and M51) low inclination, nearby spiral galaxies to study ancient star cluster populations. M81 globular clusters (GC) have an intrinsic color distribution which is very similar to those in the Milky Way and M31, with ~40% of the clusters having colors expected for a metal-rich population. On the other hand, the GC system in M51 appears almost exclusively blue and metal poor. This lack of metal-rich GCs associated with the M51 bulge indicates that the bulge formation history of this Sbc galaxy may have differed significantly from that of our own. Ancient clusters in M101, and possibly in NGC 6946, appear to have luminosity distributions which continue to rise to our detection limit (M_V ~ -6.0), well beyond the expected turnover (M_V ~ -7.4) in the luminosity function. This is reminiscent of the situation in M33, a Local Group galaxy of similar Hubble type. The faint ancient cluster candidates in M101 and NGC 6946 have colors and radii similar to their more luminous counterparts, and we suggest that these are either intermediate age (3-9 Gyr) disk clusters or the low mass end of the original GC population. If the faint, excess GC candidates are excluded, we find that the specific frequency (S_N) of ancient clusters formed in later-type spirals is roughly constant, with S_N=0.5 +- 0.2. By combining the results of this study with literature values for other systems, we find that the total GC specific frequencies in spirals appear to correlate best with Hubble type and bulge/total ratio, rather than with galaxy luminosity or galaxy mass (abridged).Comment: 31 pages, 11 tables, 10 figure

Stress Energy tensor in LCFT and the Logarithmic Sugawara construction

We discuss the partners of the stress energy tensor and their structure in Logarithmic conformal field theories. In particular we draw attention to the fundamental differences between theories with zero and non-zero central charge. However they are both characterised by at least two independent parameters. We show how, by using a generalised Sugawara construction, one can calculate the logarithmic partner of T. We show that such a construction works in the c=-2 theory using the conformal dimension one primary currents which generate a logarithmic extension of the Kac-Moody algebra.Comment: 19 pages. Minor correction

Quasinormal modes and hidden conformal symmetry in the Reissner-Nordstrom black hole

It is shown that the scalar wave equation in the near-horizon limit respects a hidden SL(2,R) invariance in the Reissner-Nordstrom (RN) black hole spacetimes. We use the SL(2,R) symmetry to determine algebraically the purely imaginary quasinormal frequencies of the RN black hole. We confirm that these are exactly quasinormal modes of scalar perturbation around the near-extremal black hole.Comment: 17 pages, 1 figure, version to appear in EPJ

Regular black hole in three dimensions

We find a new black hole in three dimensional anti-de Sitter space by introducing an anisotropic perfect fluid inspired by the noncommutative black hole. This is a regular black hole with two horizons. We compare thermodynamics of this black hole with that of non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy.Comment: 15 pages, 16 figures, 3D noncommutative black hole included as Sec 4, a version to appear in EPJ

Nonpropagation of massive mode on AdS2 in topologically massive gravity

Making use of Achucarro-Ortiz (AO) type of dimensional reduction, we study the topologically massive gravity with a negative cosmological constant on AdS2 spacetimes. For a constant dilaton, this two-dimensional model also admits three AdS2 vacuum solutions, which are related to two AdS3 and warped AdS3 backgrounds with an identification upon uplifting three dimensions. We carry out the perturbation analysis around these backgrounds to find what is a physically propagating field. However, it turns out that there is no propagating massive mode on AdS2 background, in contrast to the Kaluza-Klein (KK) type of dimensional reduction. We note that two dimensionally reduced actions are different and thus, the non-equivalence of their on-shell amplitudes is obtained.Comment: 19 pages, version to appear in EPJ

Slowly rotating black holes in the Horava-Lifshitz gravity

We investigate slowly rotating black holes in the Ho\v{r}ava-Lifshitz (HL) gravity. For $\Lambda_W=0$ and $\lambda=1$, we find a slowly rotating black hole of the Kehagias-Sfetsos solution in asymptotically flat spacetimes. We discuss their thermodynamic properties by computing mass, temperature, angular momentum, and angular velocity on the horizon.Comment: 12 pages, no figures, version to appear in EPJ

Phase transitions for the Lifshitz black holes

We study possibility of phase transitions between Lifshitz black holes and other configurations by using free energies explicitly. A phase transition between Lifshitz soliton and Lifshitz black hole might not occur in three dimensions. We find that a phase transition between Lifshitz and BTZ black holes unlikely occurs because they have different asymptotes. Similarly, we point out that any phase transition between Lifshitz and black branes unlikely occurs in four dimensions since they have different asymptotes. This is consistent with a necessary condition for taking a phase transition in the gravitational system, which requires the same asymptote.Comment: 19 pages, 7 figures, a revised version to appear in EPJ