On the Period Distribution of Close-In Extrasolar Giant Planets

Transit (TR) surveys for extrasolar planets have recently uncovered a population of ``very hot Jupiters,'' planets with orbital periods of P< 3 d. At first sight this may seem surprising, given that radial velocity (RV) surveys have found a dearth of such planets, despite the fact that their sensitivity increases with decreasing P. We examine the confrontation between RV and TR survey results, paying particular attention to selection biases that favor short-period planets in transit surveys. We demonstrate that, when such biases and small-number statistics are properly taken into account, the period distribution of planets found by RV and TR surveys are consistent at better than the 1-sigma level. This consistency holds for a large range of reasonable assumptions. In other words, there are not enough planets detected to robustly conclude that the RV and TR short-period planet results are inconsistent. Assuming a logarithmic distribution of periods, we find that the relative frequency of very hot Jupiters (VHJ: P=1-3 d) to hot Jupiters (HJ: P=3-9 d) is 10-20%. Given an absolute frequency of HJ of ~1%, this implies that approximately one star in ~500-1000 has a VHJ. We also note that VHJ and HJ appear to be distinct in terms of their upper mass limit. We discuss the implications of our results for planetary migration theories, as well as present and future TR and RV surveys.Comment: 11 pages, 4 figures, 2 tables. Minor changes. Accepted to ApJ, to appear in the April 20, 2005 issue (v623

Properties of Extremely Red Objects in an Overdense Region

We use a serendipitously discovered overdensity of extremely red objects (EROs) to study the morphologies and cumulative surface number density of EROs in a dense environment. Our extremely deep imaging allows us to select very faint EROs, reaching Ks=21, or ~2 magnitudes fainter than the L* of passively evolving ellipticals at z=1.5. We find that the shape of the ERO cumulative surface number density in our overdense field mimics that of the field ERO population over all magnitudes down to Ks=21 but with a factor of 3-4 higher normalization. The excellent seeing in our images (0.4" in Ks and 0.6" in R) allows for morphological classification of the brighter (Ks<19) EROs and we find a mix of morphologies including interacting systems and disks; the fraction of pure bulges (at most 38%), galaxies with disks (at least 46%), and interacting systems (at least 21%) is consistent with morphological fractions in field ERO studies. The similarity in the shape of the cumulative surface density and morphological mix between our overdense field and the field ERO population suggests that ERO galaxies in overdense regions at z~1-2 may not have had an appreciably different history than those in the field.Comment: uses emulateap

Hubble Space Telescope Imaging of the CFRS and LDSS Redshift Surveys. II. Structural Parameters and the Evolution of Disk Galaxies to Z approximately 1

Several aspects of the evolution of star-forming galaxies are studied using measures of the two-dimensional surface brightness profiles extracted from Hubble Space Telescope images of a sample of 341 faint objects selected from the CFRS and LDSS redshift surveys. The galaxies have 0 3.2 h^{-1}_{50} kpc, where the sample is most complete and where the disk and bulge decompositions are most reliable. This result, which is strengthened by inclusion of the local de Jong et al. size function, suggests that the scale lengths of typical disks cannot have grown substantially with cosmic epoch since z ~ 1, unless a corresponding number of large disks have been destroyed through merging. In addition to a roughly constant number density, the galaxies with large disks, alpha -1 >= 4 h^{-1}_{50} kpc, have, as a set, properties consistent with the idea that they are similar galaxies observed at different cosmic epochs. However, on average, they show higher B-band disk surface brightnesses, bluer overall (U-V) colors, higher [O II] lambda 3727 equivalent widths, and less regular morphologies at high redshift than at low redshift, suggesting an increase in the star formation rate by a factor of about 3 to z ~ 0.7. This is consistent with the expectations of recent models for the evolution of the disk of the Milky Way Galaxy. The evolution of the large disk galaxies with scale lengths alpha -1 >= 4 h^{-1}_{50} kpc, is probably not sufficient to account for the evolution of the overall luminosity function of galaxies over the interval 0 < z < 1, especially if Omega ~ 1. Analysis of the half-light radii of all the galaxies in the sample and construction of the bivariate size-luminosity function suggests that larger changes in the galaxy population are due to smaller galaxies, those with half-light radii around 5 h^{-1}_{50} kpc (i.e., disk scale lengths of 3 h^{-1}_{50} kpc or less)

Internal kinematics of CFRS galaxies at z ƒ 0.6

grantor: University of TorontoThe internal kinematics of a galaxy are closely related to its dynamical mass, and can help place constraints an the type of galaxy that is being observed; in particular, different types of galaxies show characteristic scaling relations of size and velocity width [sigma]'v', or rotation velocity 'Vrot'. In principle, these scaling relations provide clues about the nature of a galaxy independently of any changes in luminosity or morphology that may be caused by bursts of star formation. This thesis is based on a study of the internal kinematics of luminous starforming galaxies in the 0 = 0.5. New kinematic data are analysed for a sample of 30 galaxies from the Canada-France Redshift Survey, most of them with rest-frame ('U' - ' V')'AB' 0.45 have sizes (from HST images) and velocity widths [sigma]' v' (from emission lines) similar to those of typical local Irregular galaxies or very small late-type Spiral galaxies. This is consistent with their morphologies (Brinchmann et al. 1998) and rest-frame colors; however, these galaxies are as bright as the brightest local Irregular galaxies, and roughly 2 magnitudes brighter than typical Irregular galaxies known nearby. We conclude that the increase in the number density of luminous blue galaxies at 'z' >= 0.5 is mainly due to a population of small and unusually-bright late-type galaxies. This could be caused by either an increase in luminosity of some fraction of the population of small galaxies, by an increase in the number density of said population, or by a combination of both density and luminosity evolution.Ph.D

On the Size Distribution of Close-in Extrasolar Giant Planets

ABSTRACT Transit (TR) surveys for extrasolar planets have recently uncovered a population of &apos;&apos;very hot Jupiters,&apos;&apos; planets with orbital periods of P 3 days. At first sight this may seem surprising, given that radial velocity (RV) surveys have found a dearth of such planets, despite the fact that their sensitivity increases with decreasing P. We examine the confrontation between RVand TR survey results, paying particular attention to selection biases that favor short-period planets in TR surveys. We demonstrate that, when such biases and small-number statistics are properly taken into account, the period distributions of planets found by RVand TR surveys are consistent at better than the 1 level. This consistency holds for a large range of reasonable assumptions. In other words, there are not enough planets detected to robustly conclude that the RV and TR short-period planet results are inconsistent. Assuming a logarithmic distribution of periods, we find that the relative frequency of very hot Jupiters (VHJs; P ¼ 1 3 days) to hot Jupiters (HJs; P ¼ 3 9 days) is $10$1%, this implies that approximately one star in $500-1000 has a VHJ. We also note that VHJs and HJs appear to be distinct in terms of their upper mass limits. We discuss the implications of our results for planetary migration theories as well as present and future TR and RV surveys