118438022
On the eccentricity distribution of short-period single-planet systems
We apply standard Markov chain Monte Carlo (MCMC) analysis techniques to 50 short-period, single-planet systems discovered with radial velocity technique. We develop a new method for accessing the significance of a non-zero orbital eccentricity, namelyanalysis, which combines the frequentist bootstrap approach with Bayesian analysis of each simulated data set. We find that the eccentricity estimations from theanalysis are generally consistent with the results from both the standard MCMC analysis and previous references. Themethod is particular useful for assessing the significance of small eccentricities. Our results suggest that the current sample size is insufficient to draw robust conclusions about the roles of tidal interaction and perturbations in shaping the eccentricity distribution of short-period single- planet systems. We use a Bayesian population analysis to show that a mixture of analytical distributions is a good approximation of the underlying eccentricity distribution. For short- period planets, we find the most probable values of parameters in the analytical functions given the observed eccentricities. These analytical functions can be used in theoretical investigations or as priors for the eccentricity distribution when analysing short-period planets. As the measurement precision improves and sample size increases, the method can be applied to more complex parametrizations for the underlying distribution of eccentricity for extrasolar planetary systems.
119241051
PLANET HUNTERS. V. A CONFIRMED JUPITER-SIZE PLANET IN THE HABITABLE ZONE AND 42 PLANET CANDIDATES FROM THE KEPLER ARCHIVE DATA*
We report the latest Planet Hunter results, including PH2 b, a Jupiter-size (R PL = 10.12 ? 0.56 R ?) planet orbiting in the habitable zone of a solar-type star. PH2 b was elevated from candidate status when a series of false-positive tests yielded a 99.9% confidence level that transit events detected around the star KIC?12735740 had a planetary origin. Planet Hunter volunteers have also discovered 42 new planet candidates in the Kepler public archive data, of which 33 have at least 3 transits recorded. Most of these transit candidates have orbital periods longer than 100?days and 20 are potentially located in the habitable zones of their host stars. Nine candidates were detected with only two transit events and the prospective periods are longer than 400?days. The photometric models suggest that these objects have radii that range between those of Neptune and Jupiter. These detections nearly double the number of gas-giant planet candidates orbiting at habitable-zone distances. We conducted spectroscopic observations for nine of the brighter targets to improve the stellar parameters and we obtained adaptive optics imaging for four of the stars to search for blended background or foreground stars that could confuse our photometric modeling. We present an iterative analysis method to derive the stellar and planet properties and uncertainties by combining the available spectroscopic parameters, stellar evolution models, and transiting light curve parameters, weighted by the measurement errors. Planet Hunters is a citizen science project that crowd sources the assessment of NASA Kepler light curves. The discovery of these 43 planet candidates demonstrates the success of citizen scientists at identifying planet candidates, even in longer period orbits with only two or three transit events.
119233324
FUNDAMENTAL PERFORMANCE OF A DISPERSED FIXED DELAY INTERFEROMETER IN SEARCHING FOR PLANETS AROUND M DWARFS
We present a new method to calculate fundamental Doppler measurement limits with a dispersed fixed delay interferometer (DFDI) in the near-infrared (NIR) wavelength region for searching for exoplanets around M dwarfs in the coming decade. It is based on calculating the Q factor, a measure of flux-normalized Doppler sensitivity in the fringing spectra created with DFDI. We calculate the Q factor as a function of spectral resolution R, stellar-projected rotational velocity Vsin i, stellar effective temperature T eff, and optical path difference (OPD) of the interferometer. We also compare the DFDI Q factor to that for the popular cross-dispersed echelle spectrograph method (the direct echelle (DE) method). We find that (1) Q DFDI is a factor of 1.5-3 higher than Q DE at R ranging from 5000 to 20,000; (2) Q DFDI and Q DE converge at a very high R (R ≥ 100,000); (3) Q DFDI increases as R increases and Vsin i deceases; (4) for a given R, Q DFDI increases as T eff drops from 3100 K to 2400 K (M4V to M9V). We also investigate how Q DFDI is affected by OPD and find that a 5 mm deviation from the optimal OPD does not significantly affect Q DFDI (10% or less) for a wide range of R. Given that the NIR Doppler measurement is likely to be detector-limited for a while, we introduce new merit functions, which is directly related to photon-limited radial velocity (RV) uncertainty, to evaluate Doppler performance with the DFDI and DE methods. We find that DFDI has strength in wavelength coverage and multi-object capability over the DE for a limited detector resource. We simulate the performance of the InfraRed Exoplanet Tracker (IRET) based on the DFDI design, being considered for the next generation IR Doppler measurements. The predicted photon-limited RV uncertainty suggests that IRET is capable of detecting Earth-like exoplanets in habitable zone around nearby bright M dwarfs if they exist. A new method is developed to quantitatively estimate the influence of telluric lines on RV uncertainty. Our study shows that photon-limited RV uncertainty can be reached if 99% of the strength of telluric lines can be removed from the measured stellar spectra. At low to moderate levels of telluric line strength removal (50%-90%), the optimal RV uncertainty is typically a factor of two to three times larger than photon-limited RV uncertainty.
8075527
A Third Planet Orbiting HIP 14810
We present new precision radial velocities and a three-planet Keplerian orbit fit for the V = 8.5, G5 V star HIP 14810. We began observing this star at Keck Observatory as part of the N2K Planet Search Project. Wright et al. (2007) announced the inner two planets to this system, and subsequent observations have revealed the outer planet planet and the proper orbital solution for the middle planet. The planets have minimum masses of 3.9, 1.3, and 0.6 M_Jup and orbital periods of 6.67, 147.7, and 952 d, respectively. We have numerically integrated the family of orbital solutions consistent with the data and find that they are stable for at least 10^6 yr. Our photometric search shows that the inner planet does not transit.
20026118
The ninth data release of the sloan digital sky survey: first spectroscopic data from the sdss-iiI baryon oscillation spectroscopic survey
The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z ~ 0.52), 102,100 new quasar spectra (median z ~ 2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T eff -0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SEGUE-2. The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the APOGEE along with another year of data from BOSS, followed by the final SDSS-III data release in 2014 December.
14172815
SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way, and Extra-Solar Planetary Systems
Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS DR8 (which occurred in Jan 2011). This paper presents an overview of the four SDSS-III surveys. BOSS will measure redshifts of 1.5 million massive galaxies and Lya forest spectra of 150,000 quasars, using the BAO feature of large scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z 100 per resolution element), H-band (1.51-1.70 micron) spectra of 10^5 evolved, late-type stars, measuring separate abundances for ~15 elements per star and creating the first high-precision spectroscopic survey of all Galactic stellar populations (bulge, bar, disks, halo) with a uniform set of stellar tracers and spectral diagnostics. MARVELS will monitor radial velocities of more than 8000 FGK stars with the sensitivity and cadence (10-40 m/s, ~24 visits per star) needed to detect giant planets with periods up to two years, providing an unprecedented data set for understanding the formation and dynamical evolution of giant planet systems. (Abridged)
55082285
GRB 071112C: A Case Study of Different Mechanisms in X-ray and Optical Temporal Evolution
We present a study on GRB 071112C X-ray and optical light curves. In these two wavelength ranges, we have found different temporal properties. The R-band light curve showed an initial rise followed by a single power-law decay, while the X-ray light curve was described by a single power-law decay plus a flare-like feature. Our analysis shows that the observed temporal evolution cannot be described by the external shock model in which the X-ray and optical emission are produced by the same emission mechanism. No significant color changes in multi-band light curves and a reasonable value of the initial Lorentz factor ({Gamma}{sub 0} = 275 {+-} 20) in a uniform interstellar medium support the afterglow onset scenario as the correct interpretation for the early R band rise. The result suggests that the optical flux is dominated by afterglow. Our further investigations show that the X-ray flux could be created by an additional feature related to energy injection and X-ray afterglow. Different theoretical interpretations indicate the additional feature in X-ray can be explained by either late internal dissipation or local inverse-Compton scattering in the external shock.
118448349
A BAYESIAN APPROACH TO ESTIMATE THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI USING REVERBERATION MAPPING DATA
This is the first paper in a series devoted to the systematic study of the size and structure of the broad-line region (BLR) in active galactic nuclei (AGNs) using reverberation mapping (RM) data. We employ a recently developed Bayesian approach that statistically describes the variability as a damped random walk process and delineates the BLR structure using a flexible disk geometry that can account for a variety of shapes, including disks, rings, shells, and spheres. We allow for the possibility that the line emission may respond non-linearly to the continuum, and we detrend the light curves when there is clear evidence for secular variation. We use a Markov Chain Monte Carlo implementation based on Bayesian statistics to recover the parameters and uncertainties for the BLR model. The corresponding transfer function is obtained self-consistently. We tentatively constrain the virial factor used to estimate black holemasses; more accurate determinations will have to await velocity-resolved RM data. Application of our method to RM data with H beta monitoring for about 40 objects shows that the assumed BLR geometry can reproduce quite well the observed emission-line fluxes from the continuum light curves. We find that the H beta BLR sizes obtained from our method are on average similar to 20% larger than those derived from the traditional cross-correlation method. Nevertheless, we still find a tight BLR size-luminosity relation with a slope of alpha = 0.55 +/- 0.03 and an intrinsic scatter of similar to 0.18 dex. In particular, we demonstrate that our approach yields appropriate BLR sizes for some objects (such as Mrk 142 and PG 2130+099) where traditional methods previously encountered difficulties.
122925118
Monte Carlo simulation of the response of Si(Li) detectors to monoenergetic X-rays
Abstract We present a Monte Carlo simulation of X-ray interaction with a Si(Li) detector which includes for the first time both a detailed description of the atomic excitation and de-excitation and also a physically realistic model of the frontal region of incomplete charge collection. Simulated lineshapes are in good agreement with those measured by us using monoenergetic X-rays of energy 1–10 keV and by varying the two parameters of the model we can generate lineshapes very similar to those reported in the literature for other Si(Li) detectors.
88509175
Measurement of the Drell-Yan cross section in pp collisions at $ \sqrt {s} = 7 $ TeV
The Drell-Yan differential cross section is measured in pp collisions at $ \sqrt {s} = 7 $ TeV, from a data sample collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 36 pb−1. The cross section measurement, normalized to the measured cross section in the Z region, is reported for both the dimuon and dielectron channels in the dilepton invariant mass range 15–600 GeV. The normalized cross section values are quoted both in the full phase space and within the detector acceptance. The effect of final state radiation is also identified. The results are found to agree with theoretical predictions.
54964991
A graphical analysis of the systematic error of classical binned methods in constructing luminosity functions
The classical 1/Va and PC methods of constructing binned luminosity functions (LFs) are revisited and compared by graphical analysis. Using both theoretical analysis and illustration with an example, we show why the two methods give different results for the bins which are crossed by the flux limit curves L=Llim(z). Based on a combined sample simulated by a Monte Carlo method, the estimate ϕ of two methods are compared with the input model LFs. The two methods give identical and ideal estimate for the high luminosity points of each redshift interval. However, for the low luminosity bins of all the redshift intervals both methods give smaller estimate than the input model. We conclude that once the LF is evolving with redshift, the classical binned methods will unlikely give an ideal estimate over the total luminosity range. Page & Carrera (in Mon. Not. R. Astron. Soc. 311:433, 2000) noticed that for objects close to the flux limit $\phi_{1/V_{a}}$ nearly always to be too small. We believe this is due to the arbitrary choosing of redshift and luminosity intervals. Because $\phi_{1/V_{a}}$ is more sensitive to how the binning are chosen than ϕPC. We suggest a new binning method, which can improve the LFs produced by the 1/Va method significantly, and also improve the LFs produced by the PC methods. Our simulations show that after adopting this new binning, both the 1/Va and PC methods have comparable results.