Exact correlations in a single file system with a driven tracer

We study the effect of a single driven tracer particle in a bath of other particles performing the random average process on an infinite line using a stochastic hydrodynamics approach. We consider arbitrary fixed as well as random initial conditions and compute the two-point correlations. For quenched uniform and annealed steady state initial conditions we show that in the large time $T$ limit the fluctuations and the correlations of the positions of the particles grow subdiffusively as $\sqrt{T}$ and have well defined scaling forms under proper rescaling of the labels. We compute the corresponding scaling functions exactly for these specific initial configurations and verify them numerically. We also consider a non translationally invariant initial condition with linearly increasing gaps where we show that the fluctuations and correlations grow superdiffusively as $T^{3/2}$ at large times.Comment: 7 pages, 4 figures, supplementary material appended. To appear in EP

On a low energy bound in a class of chiral field theories with solitons

A low energy bound in a class of chiral solitonic field theories related the infrared physics of the SU(N) Yang-Mills theory is established.Comment: Plain Latex, 8 pages, no figure

The Luminosity Function of Young Star Clusters In "The Antennae" Galaxies (NGC 4038/4039)

The WFPC2 of the HST has been used to obtain high-resolution images of NGC 4038/4039 that go roughly 3 magnitudes deeper in V than previous observations made during Cycle 2 (-14 < M_V < -6). To first order the luminosity function (LF) is a power law, with exponent \alpha = -2.12 +/- 0.04. However, after decoupling the cluster and stellar LFs, which overlap in the range -9 < M_V < -6, we find an apparent bend in the young cluster LF at approximately M_V = -10.4. The LF has a power law exponent -2.6 +/- 0.2 in the brightward and -1.7 +/- 0.2 in the faintward. The bend corresponds to a mass ~ 10^5 M_{\odot}, only slightly lower than the characteristic mass of globular clusters in the Milky Way (~2x10^5 M_{\odot}). The star clusters of the Antennae appear slightly resolved, with median effective radii of 4 +/- 1 pc, similar to or perhaps slightly larger than those of globular clusters in our Galaxy. However, the radial extents of some of the very young clusters (ages < 10 Myr) are much larger than those of old globular clusters. A combination of the UBVI colors, \Halpha morphology, and GHRS spectra enables us to age-date the clusters in different regions of The Antennae. We find two groups of young star clusters with ages <~ 20Myr and ~100Myr, as well as an intermediate-age group (~500 Myr) and a handful of old globular clusters from the progenitor galaxies. Age estimates derived from GHRS spectroscopy yield 3 +/- 1 Myr for Knot K (just south of the nucleus of NGC 4038) and 7 +/- 1 Myr for Knot S in the Western Loop, in good agreement with ages derived from the UBVI colors. Effective gas-outflow velocities from Knots S and K are estimated to be about 25-30 km/s. However, the measured widths of the interstellar absorption lines suggest dispersion velocities of ~400 km/s along the lines of sight to Knots S and K.Comment: 56 pages, 4 tables and 23 figures, texts in AAS style, to be published in A

The Globular Cluster Systems in the Coma Ellipticals. II: Metallicity Distribution and Radial Structure in NGC 4874, and Implications for Galaxy Formation

Deep HST/WFPC2 (V,I) photometry is used to investigate the globular cluster system (GCS) in NGC 4874, the central cD galaxy of the Coma cluster. The luminosity function of the clusters displays its normal Gaussian-like shape and turnover level. Other features of the system are surprising: the GCS is (a) spatially extended, with core radius r_c = 22 kpc, (b) entirely metal-poor (a narrow, unimodal metallicity distribution with mean [Fe/H] = -1.5), and (c) modestly populated, with specific frequency S_N = 3.7 +- 0.5. We suggest on the basis of some simple models that as much as half of this galaxy might have accreted from low-mass satellites, but no single one of the three classic modes of galaxy formation (accretion, disk mergers, in situ formation) can supply a fully satisfactory formation picture. Even when they are used in combination, strong challenges to these models remain. The principal anomaly in this GCS is essentially the complete lack of metal-rich clusters. If these were present in normal (M87-like) numbers in addition to the metal-poor ones that are already there, then the GCS in total would more closely resemble what we see in many other giant E galaxies.Comment: 27 pp. with 9 Figures. Astrophys.J. 533, in press (April 10, 2000

Constraints on the mass and abundance of black holes in the Galactic halo: the high mass limit

We establish constraints on the mass and abundance of black holes in the Galactic halo by determining their impact on globular clusters which are conventionally considered to be little evolved. Using detailed Monte Carlo simulations and simple analytic estimates, we conclude that, at Galactocentric radius R~8 kpc, black holes with masses M_bh >~(1-3) x 10^6 M_sun can comprise no more than a fraction f_bh ~ 0.025-0.05 of the total halo density. This constraint significantly improves those based on disk heating and dynamical friction arguments as well as current lensing results. At smaller radius, the constraint on f_bh strengthens, while, at larger radius, an increased fraction of black holes is allowed.Comment: 13 pages, 10 figures, revised version, in press, Monthly Notice

The Globular Cluster Systems in the Coma Ellipticals. III: The Unique Case of IC 4051

Using archival \hst WFPC2 data, we derive the metallicity distribution, luminosity function, and spatial structure of the globular cluster system around IC 4051, a giant E galaxy on the outskirts of the Coma cluster core. The metallicity distribution derived from the (V-I) colors has a mean [Fe/H] = -0.3, a near-complete lack of metal-poor clusters, and only a small metallicity gradient with radius; it may, however, have two roughly equal metallicity subcomponents, centered at [Fe/H] ~ 0.0 and -1.0. The luminosity distribution (GCLF) has the Gaussian-like form observed in all other giant E galaxies, with a peak (turnover) at V = 27.8, consistent with a Coma distance of 100 Mpc. The radial profiles of both the GCS and the halo light show an unusually steep falloff which may indicate that the halo of this galaxy has been tidally truncated. Lastly, the specific frequency of the GCS is remarkably large: we find S_N = 11 +- 2, resembling the central cD-type galaxies even though IC 4051 is not a cD or brightest cluster elliptical. A formation model consistent with most of the observations would be that this galaxy was subjected to removal of a large fraction of its protogalactic gas shortly after its main phase of globular cluster formation, probably by its first passage through the Coma core. Since then, no significant additions due to accretions or mergers have taken place.Comment: 24 pp. plus 13 Figures. Postscript file for the complete paper can also be downloaded from http://www.physun.mcmaster.ca/~harris/WEHarris.html. Astron.J., in pres