Scattered Lyman-alpha Radiation Around Sources Before Cosmological Reionization

The spectra of the first galaxies and quasars in the Universe should be strongly absorbed shortward of their rest-frame Lyman-alpha wavelength by neutral hydrogen (HI) in the intervening intergalactic medium. However, the Lyman-alpha line photons emitted by these sources are not eliminated but rather scatter until they redshift out of resonance and escape due to the Hubble expansion of the surrounding intergalactic HI. We calculate the resulting brightness distribution and the spectral shape of the diffuse Lyman-alpha line emission around high redshift sources, before the intergalactic medium was reionized. Typically, the Lyman-alpha photons emitted by a source at z=10 scatter over a characteristic angular radius of order 15 arcseconds around the source and compose a line which is broadened and redshifted by about a thousand km/s relative to the source. The scattered photons are highly polarized. Detection of the diffuse Lyman-alpha halos around high redshift sources would provide a unique tool for probing the neutral intergalactic medium before the epoch of reionization. On sufficiently large scales where the Hubble flow is smooth and the gas is neutral, the Lyman-alpha brightness distribution can be used to determine the cosmological mass densities of baryons and matter.Comment: 21 pages, 5 Postscript figures, accepted by ApJ; figures 1--3 corrected; new section added on the detectability of Lyman alpha halos; conclusions update

Cometary Astrometry

Modern techniques for making cometary astrometric observations, reducing these observations, using accurate reference star catalogs, and computing precise orbits and ephemerides are discussed in detail and recommendations and suggestions are given in each area

A Spitzer Five-Band Analysis of the Jupiter-Sized Planet TrES-1

With an equilibrium temperature of 1200 K, TrES-1 is one of the coolest hot Jupiters observed by {\Spitzer}. It was also the first planet discovered by any transit survey and one of the first exoplanets from which thermal emission was directly observed. We analyzed all {\Spitzer} eclipse and transit data for TrES-1 and obtained its eclipse depths and brightness temperatures in the 3.6 {\micron} (0.083 % {\pm} 0.024 %, 1270 {\pm} 110 K), 4.5 {\micron} (0.094 % {\pm} 0.024 %, 1126 {\pm} 90 K), 5.8 {\micron} (0.162 % {\pm} 0.042 %, 1205 {\pm} 130 K), 8.0 {\micron} (0.213 % {\pm} 0.042 %, 1190 {\pm} 130 K), and 16 {\micron} (0.33 % {\pm} 0.12 %, 1270 {\pm} 310 K) bands. The eclipse depths can be explained, within 1$\sigma$ errors, by a standard atmospheric model with solar abundance composition in chemical equilibrium, with or without a thermal inversion. The combined analysis of the transit, eclipse, and radial-velocity ephemerides gives an eccentricity $e = 0.033^{+0.015}_{-0.031}$, consistent with a circular orbit. Since TrES-1's eclipses have low signal-to-noise ratios, we implemented optimal photometry and differential-evolution Markov-chain Monte Carlo (MCMC) algorithms in our Photometry for Orbits, Eclipses, and Transits (POET) pipeline. Benefits include higher photometric precision and \sim10 times faster MCMC convergence, with better exploration of the phase space and no manual parameter tuning.Comment: 17 pages, Accepted for publication in Ap

Spitzer 3.6 micron and 4.5 micron full-orbit lightcurves of WASP-18

We present new lightcurves of the massive hot Jupiter system WASP-18 obtained with the Spitzer spacecraft covering the entire orbit at 3.6 micron and 4.5 micron. These lightcurves are used to measure the amplitude, shape and phase of the thermal phase effect for WASP-18b. We find that our results for the thermal phase effect are limited to an accuracy of about 0.01% by systematic noise sources of unknown origin. At this level of accuracy we find that the thermal phase effect has a peak-to-peak amplitude approximately equal to the secondary eclipse depth, has a sinusoidal shape and that the maximum brightness occurs at the same phase as mid-occultation to within about 5 degrees at 3.6 micron and to within about 10 degrees at 4.5 micron. The shape and amplitude of the thermal phase curve imply very low levels of heat redistribution within the atmosphere of the planet. We also perform a separate analysis to determine the system geometry by fitting a lightcurve model to the data covering the occultation and the transit. The secondary eclipse depths we measure at 3.6 micron and 4.5 micron are in good agreement with previous measurements and imply a very low albedo for WASP-18b. The parameters of the system (masses, radii, etc.) derived from our analysis are in also good agreement with those from previous studies, but with improved precision. We use new high-resolution imaging and published limits on the rate of change of the mean radial velocity to check for the presence of any faint companion stars that may affect our results. We find that there is unlikely to be any significant contribution to the flux at Spitzer wavelengths from a stellar companion to WASP-18. We find that there is no evidence for variations in the times of eclipse from a linear ephemeris greater than about 100 seconds over 3 years.Comment: 17 pages, 10 figures. Accpeted for publication in MNRA

Total Molecular Gas Masses of Planck - Herschel Selected Strongly Lensed Hyper Luminous Infrared Galaxies

We report the detection of CO(1 - 0) line emission from seven Planck and Herschel selected hyper luminous (LIR(8-1000um) > 10^13Lsun) infrared galaxies with the Green Bank Telescope (GBT). CO(1 - 0) measurements are a vital tool to trace the bulk molecular gas mass across all redshifts. Our results place tight constraints on the total gas content of these most apparently luminous high-z star-forming galaxies (apparent IR luminosities of LIR > 10^(13-14) Lsun), while we confirm their predetermined redshifts measured using the Large Millimeter Telescope, LMT (zCO = 1.33 - 3.26). The CO(1 - 0) lines show similar profiles as compared to Jup = 2 -4 transitions previously observed with the LMT. We report enhanced infrared to CO line luminosity ratios of = 110 (pm 22) Lsun(K km s^-1 pc^-2)^-1 compared to normal star-forming galaxies, yet similar to those of well-studied IR-luminous galaxies at high-z. We find average brightness temperature ratios of = 0.93 (2 sources), = 0.34 (5 sources), and = 0.18 (1 source). The r31 and r41 values are roughly half the average values for SMGs. We estimate the total gas mass content as uMH2 = (0.9 - 27.2) x 10^11(alphaCO/0.8)Msun, where u is the magnification factor and alphaCO is the CO line luminosity to molecular hydrogen gas mass conversion factor. The rapid gas depletion times are, on average, tau = 80 Myr, which reveal vigorous starburst activity, and contrast the Gyr depletion timescales observed in local, normal star-forming galaxies.Comment: published in MNRAS, 9pages, 5fig

Temperature dependence of instantons in QCD

We investigate the temperature dependence of the instanton contents of gluon fields, using unquenched lattice QCD and the cooling method. The instanton size parameter deduced from the correlation function decreases from 0.44fm below the phase-transition temperature $T_c$ ($\approx 150$MeV) to 0.33fm at 1.3 $T_c$. The instanton charge distribution is Poissonian above $T_c$, but it deviates from the convoluted Poisson at low temperature. The topological susceptibility decreases rapidly below $T_c$, showing the apparent restoration of the $U(1)_A$ symmetry already at $T \approx T_c$.Comment: 8 pages TEX, 3 Postscript figures available at http://www.krl.caltech.edu/preprints/MAP.htm

The phase-dependent Infrared brightness of the extrasolar planet upsilon Andromedae b

The star upsilon Andromeda is orbited by three known planets, the innermost of which has an orbital period of 4.617 days and a mass at least 0.69 that of Jupiter. This planet is close enough to its host star that the radiation it absorbs overwhelms its internal heat losses. Here we present the 24 micron light curve of this system, obtained with the Spitzer Space Telescope. It shows a clear variation in phase with the orbital motion of the innermost planet. This is the first demonstration that such planets possess distinct hot substellar (day) and cold antistellar (night) faces.Comment: "Director's cut" of paper to appear in Science, 27 October, 200