L.-Y Chiang
A5025841494- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Scientific Research and Discoveries
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Relativity and Gravitational Theory
- Geophysics and Gravity Measurements
- Gamma-ray bursts and supernovae
- Advanced Differential Geometry Research
- Advanced Thermodynamics and Statistical Mechanics
- Calibration and Measurement Techniques
- Neutrino Physics Research
- Radioactive Decay and Measurement Techniques
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Statistical Mechanics and Entropy
- Geomagnetism and Paleomagnetism Studies
- Scientific Measurement and Uncertainty Evaluation
- Spectroscopy and Laser Applications
Institute of Astronomy and Astrophysics, Academia Sinica
2007-2018
Academia Sinica
2012-2014
Agenzia Spaziale Italiana
2012
Aalto University
2012
National Taiwan University
2012
European Space Research Institute
2012
Chuo University
2011
National Tsing Hua University
2007
University of Copenhagen
2004
University of Central Lancashire
2002
We present the first results based on Planck measurements of CMB temperature and lensing-potential power spectra. The spectra at high multipoles are extremely well described by standard spatially-flat six-parameter LCDM cosmology. In this model data determine cosmological parameters to precision. find a low value Hubble constant, H0=67.3+/-1.2 km/s/Mpc matter density parameter, Omega_m=0.315+/-0.017 (+/-1 sigma errors) in excellent agreement with constraints from baryon acoustic oscillation...
The ESA's Planck satellite, dedicated to studying the early Universe and its subsequent evolution, was launched 14 May 2009 has been scanning microwave submillimetre sky continuously since 12 August 2009. This paper gives an overview of mission performance, processing, analysis, characteristics data, scientific results, science data products papers in release. include maps CMB diffuse extragalactic foregrounds, a catalogue compact Galactic sources, list sources detected through SZ effect....
We analyse the implications of Planck data for cosmic inflation. The nominal mission temperature anisotropy measurements, combined with WMAP large-angle polarization, constrain scalar spectral index to $n_s = 0.9603 \pm 0.0073$, ruling out exact scale invariance at over 5 $\sigma$. establishes an upper bound on tensor-to-scalar ratio r < 0.11 (95% CL). thus shrink space allowed standard inflationary models, preferring potentials V" 0. Exponential potential simplest hybrid and monomial models...
This paper characterizes the effective beams,the beam window functions and associated errors for Planck HFI detectors. The is angular response including effect of optics,detectors,data processing scan strategy. function representation this in harmonic domain which required to recover an unbiased measurement CMB power spectrum. a scanning instrument its beams are convolution of: (a) optical telescope feeds;(b)the time-ordered data deconvolution bolometric electronic time response; (c) merging...
The two fundamental assumptions of the standard cosmological model - that initial fluctuations are statistically isotropic and Gaussian rigorously tested using maps cosmic microwave background (CMB) anisotropy from Planck satellite. Deviations isotropy have been found demonstrated to be robust against component separation algorithm, mask choice frequency dependence. Many these anomalies were previously observed in WMAP data, now confirmed at similar levels significance (about 3 sigma)....
We present constraints on cosmological parameters using number counts as a function of redshift for sub-sample 189 galaxy clusters from the Planck SZ (PSZ) catalogue. The PSZ is selected through signature Sunyaev--Zeldovich (SZ) effect, and used here has signal-to-noise threshold seven, with each object confirmed cluster all but one estimate. discuss completeness sample our construction likelihood analysis. Using relation between mass $M$ signal $Y$ calibrated to X-ray measurements, we...
The Planck nominal mission cosmic microwave background (CMB) maps yield unprecedented constraints on primordial non-Gaussianity (NG). Using three optimal bispectrum estimators, separable template-fitting (KSW), binned, and modal, we obtain consistent values for the local, equilateral, orthogonal amplitudes, quoting as our final result fNL^local= 2.7+/-5.8, fNL^equil= -42+/-75, fNL^ortho= -25+\-39 (68% CL statistical). NG is detected in data; using skew-C_l statistics find a nonzero from...
This paper presents an all-sky model of dust emission from the Planck 857, 545 and 353 GHz, IRAS 100 micron data. Using a modified black-body fit to data we present maps optical depth, temperature, spectral index over 353-3000 GHz range. is tight representation at 5 arc min. It shows variations order 30 % compared with widely-used Finkbeiner, Davis, Schlegel. The allow us estimate temperature uniformly whole sky, providing improved depth previous model, especially in high-contrast molecular...
We present the Planck likelihood, a complete statistical description of two-point correlation function CMB temperature fluctuations. use this likelihood to derive power spectrum over three decades in l, covering 2 <= l 2500. The main source error at 1500 is cosmic variance. Uncertainties small-scale foreground modelling and instrumental noise dominate budget higher l's. For < 50, our exploits all frequency channels from 30 353 GHz through physically motivated Bayesian component separation...
An all sky map of the apparent temperature and optical depth thermal dust emission is constructed using Planck-HFI (350μm to 2 mm) andIRAS(100μm) data. The maps are correlated with tracers atomic (Hi) molecular gas traced by CO. correlation column density observed linear in lowest regions at high Galactic latitudes. At NH, consistent that for a given choice CO-to-H2 conversion factor. In intermediate NH range, departure from linearity observed, excess correlation. This attributed associated...
The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably continuously since 13 August 2009. Its performance is well in line with expectations, it will continue to gather scientific data until end of its cryogenic lifetime. We give an overview history first year operations, describe some key aspects satellite. This paper part a package submitted conjunction Planck's Early Release Compact Source Catalogue, product based be released...
We describe the all-sky Planck catalogue of clusters and cluster candidates derived from Sunyaev--Zeldovich (SZ) effect detections using first 15.5 months satellite observations. The contains 1227 entries, making it over six times size Early SZ (ESZ) sample largest SZ-selected to date. It 861 confirmed clusters, which 178 have been as mostly through follow-up observations, a further 683 are previously-known clusters. remaining 366 status candidates, we divide them into three classes...
The European Space Agency's <i>Planck<i/> satellite, launched on 14 May 2009, is the third-generation space experiment in field of cosmic microwave background (CMB) research. It will image anisotropies CMB over whole sky, with unprecedented sensitivity ( ~ 2 × 10<sup>-6<sup/>) and angular resolution (~5 arcmin). provide a major source information relevant to many fundamental cosmological problems test current theories early evolution Universe origin structure. also address wide range areas...
We present the first all-sky sample of galaxy clusters detected blindly by Planck satellite through Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) is comprised 189 candidates, which have a high signal-to-noise ratio ranging 6 to 29. Its reliability (purity above 95%) further ensured an extensive validation process based on internal quality assessments and external cross-identification follow-up observations. provides measured signal for about 80% 169...
Taking advantage of the all-sky coverage and broadfrequency range Planck satellite, we study Sunyaev-Zeldovich (SZ) pressure profiles 62 nearby massive clusters detected at high significance in 14-month nominal survey. Careful reconstruction SZ signal indicates that most are individually least out to R500. By stacking radial profiles, have statistically 3 × R500, i.e., a density contrast about 50–100, though dispersion mean profile dominates statistical errors across whole range. Our...
On the arcminute angular scales probed by Planck, cosmic microwave background (CMB) anisotropies are gently perturbed gravitational lensing. Here we present a detailed study of this effect, detecting lensing independently in 100, 143, and 217 GHz frequency bands with an overall significance greater than 25σ. We use thetemperature-gradient correlations induced to reconstruct (noisy) map CMB potential, which provides integrated measure mass distribution back last-scattering surface. Our...
Planck data have been used to provide stringent new constraints on cosmic strings and other defects. We describe forecasts of the CMB power spectrum induced by strings, calculating these from network models simulations using line-of-sight Boltzmann solvers. studied Nambu-Goto as well field theory for which radiative effects are important, thus spanning range theoretical uncertainty in models. added angular that a simple adiabatic model, with extra fraction defined $f_{10}$ at multipole...
Planck has produced detailed all-sky observations over nine frequency bands between 30 and 857 GHz. These allow robust reconstruction of the primordial cosmic microwave background (CMB) temperature fluctuations nearly full sky, as well new constraints on Galactic foregrounds, including thermal dust line emission from molecular carbon monoxide (CO). This paper describes component separation framework adopted by for many cosmological analyses, CMB power spectrum determination likelihood...
(Abridged) A brief description of the methodology construction, contents and usage Planck Early Release Compact Source Catalogue (ERCSC), including Cold Cores (ECC) Sunyaev-Zeldovich (ESZ) cluster catalogue is provided. The based on data that consist mapping entire sky once 60% a second time by Planck, thereby comprising first high sensitivity radio/submillimetre observations sky. Monte-Carlo algorithm injection extraction artificial sources into maps was implemented to select reliable among...
We present new measurements of CIB anisotropies using Planck. Combining HFI data with IRAS, the angular auto- and cross frequency power spectrum is measured from 143 to 3000 GHz, auto-bispectrum 217 545 GHz. The total areas used compute bispectrum are about 2240 4400 deg^2, respectively. After careful removal contaminants, a complete study systematics, unprecedented signal noise ratio multipoles ell~150 2500, ell~130 1100, Two approaches developed for modelling anisotropies. first approach...
We present the statistical properties of first version Cold Core Catalogue Planck Objects (C3PO), in terms their spatial distribution, temperature, distance, mass, and morphology. also describe statistics Early (ECC, delivered with Release Compact Source Catalogue, ERCSC) that is subset 915 most reliable detections complete catalogue. have used CoCoCoDeT algorithm to extract 10783 cold sources. Temperature dust emission spectral index {\beta} values are derived using fluxes IRAS 100 \mum...
We present precise Sunyaev-Zeldovich (SZ) effect measurements in the direction of 62 nearby galaxy clusters (z <0.5) detected at high signal-to-noise first Planck all-sky dataset. The sample spans approximately a decade total mass, 10^14 < M_500 10^15, where is mass corresponding to density contrast 500. Combining these quality with deep XMM-Newton X-ray data, we investigate relations between D_A^2 Y_500, integrated Compton parameter due SZ effect, and X-ray-derived gas M_g,500, temperature...
The Planck High Frequency Instrument (HFI) spectral response was determined through a series of ground based tests conducted with the HFI focal plane in cryogenic environment prior to launch. main goal transmission measure relative (including out-of-band signal rejection) all detectors. This by measuring output continuously scanned Fourier transform spectrometer coupled As there is no on-board within HFI, ground-based experiments provide definitive data set for calibration HFI. used analysis...