A5100671583- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- SAS software applications and methods
- Adaptive optics and wavefront sensing
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Cosmology and Gravitation Theories
- Atomic and Molecular Physics
- Scientific Research and Discoveries
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Photocathodes and Microchannel Plates
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- CCD and CMOS Imaging Sensors
- Atmospheric Ozone and Climate
- Real-Time Systems Scheduling
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
Johns Hopkins University
2014-2023
University of California, Berkeley
1988-2022
Hebei University
2022
Space Telescope Science Institute
2005-2015
Bloomberg (United States)
1998-2013
University of Michigan–Ann Arbor
2012
Shenyang Normal University
2010
Observatoire astronomique de Strasbourg
2009
Mount Stromlo Observatory
2009
City University of Hong Kong
2007
We have created a variety of composite quasar spectra using homogeneous data set over 2200 from the Sloan Digital Sky Survey (SDSS). The sample spans redshift range 0.044 ≤ z 4.789 and an absolute r' magnitude -18.0 to -26.5. input cover observed wavelength 3800–9200 Å at resolution 1800. median covers rest-wavelength 800 8555 reaches peak signal-to-noise ratio 300 per 1 element in rest frame. identified 80 emission-line features spectrum. Emission-line shifts relative nominal laboratory...
The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit multi-cycle treasury program to use the gravitational lensing properties of 25 galaxy clusters accurately constrain their mass distributions. survey, described in detail this paper, will definitively establish degree concentration dark matter cluster cores, key prediction CDM. CLASH sample larger and less biased than current samples space-based imaging studies similar depth, as we have minimized lensing-based...
In this paper we present the source catalog obtained from a 942 ks exposure of Chandra Deep Field South (CDFS), using Advanced CCD Imaging Spectrometer (ACIS-I) on X-ray Observatory. Eleven individual pointings made between 1999 October and 2000 December were combined to generate final image used for object detection. Catalog generation proceeded simultaneously two different methods; method our own design modified version SExtractor algorithm, wavelet transform technique developed...
We present the results of our spectroscopic follow-up program X-ray sources detected in 942 ks exposure Chandra Deep Field-South (CDFS). A total 288 possible counterparts were observed at VLT with FORS1/FORS2 spectrographs for 251 349 (including three additional faint sources). Spectra and R-band images are shown all R - K colors given most them. Spectroscopic redshifts obtained 168 sources, which 137 have both reliable optical identification redshift estimate 16 external identifications)....
We use a sample of 332 Hubble Space Telescope spectra 184 quasi-stellar objects (QSOs) with z > 0.33 to study the typical ultraviolet spectral properties QSOs, emphasis on ionizing continuum. Our is nearly twice as large that from previous work by W. Zheng and colleagues provides much better coverage in extreme-ultraviolet (EUV). The overall composite continuum can be described power law index αEUV = -1.76 ± 0.12 (fν ∝ να) between 500 1200 Å. corresponding results for subsamples radio-quiet...
We present our first results from 120 ks of X-ray observations obtained with the Advanced CCD Imaging Spectrometer on Chandra X-Ray Observatory. The field two combined exposures is 0.096 deg2 and detection limit to a S/N 2 (corresponding ~7 net counts). reach flux × 10-16 erg s-1 cm-2 in 0.5-2 keV soft band 10-15 2-10 hard band. Our sample has 144 sources 91 sources, for total 159 sources. Fifteen are detected only band, 68 For optical identification, we carried out survey VRI FORS-1 imaging...
We construct a composite quasar spectrum from 284 HST FOS spectra of 101 quasars with redshifts z > 0.33. The covers the wavelengths between 350 and 3000 Å in rest frame, peak S/N level ~130 per at ~1200 Å. Since ~90% sample have redshift < 1.5, is suitable for studying wavelength region shortward Lyα without large effects intervening forest absorption. Data waveband 600 are mainly 1.5 quasars, which significant corrections accumulated Lyman-series line continuum absorption been applied.
We present 0.6-2.5 μm, R ≳ 400 spectra of 27 cool, low-luminosity stars and substellar objects. Based on these previously published spectra, we develop a preliminary spectral classification system for L T dwarfs. For late types the is based entirely four indices in 1-2.5 μm interval. Two are derived from water absorption bands at 1.15 1.4 latter which shows smooth increase depth through sequences can be used to classify both types. The other two make use methane features H K bands, with...
We measure the morphology--density relation (MDR) and morphology-radius (MRR) for galaxies in seven z ~ 1 clusters that have been observed with Advanced Camera Surveys on board Hubble Space Telescope. Simulations independent comparisons of ourvisually derived morphologies indicate ACS allows one to distinguish between E, S0, spiral down zmag = 24, corresponding L/L* 0.21 0.30 at 0.83 1.24, respectively. adopt density radius estimation methods match those used lower redshift order study...
We have compiled L' and M' photometry of 63 single binary M, L,and T dwarfs obtained at UKIRT using the MKO filter set. This compilation includes new data for 8 L 13 7 dwarfs, 5 Gl 229A. compute L_bol, BC_K, T_eff 42 whose flux-calibrated JHK spectra, photometry, trigonometric parallaxes are available, we estimate these quantities 9 other spectra been obtained. BC_K is a well-behaved function near-IR spectral type with dispersion ~0.1 mag types M6-T5; it significantly more scattered T5-T9....
We present a detailed X-ray spectral analysis of the sources in 1Ms catalog Chandra Deep Field South (CDFS) taking advantage optical spectroscopy and photometric redshifts for 321 extragalactic out total sample 347 sources. As default model, we adopt power law with slope Γ an intrinsic redshifted absorption NH, fixed Galactic unresolved Fe emission line. For 82 bright sources, are able to perform leaving both NH free. The weighted mean value is , distribution best fit values shows dispersion...
We present a candidate for the most distant galaxy known to date with photometric redshift of z = 10.7+0.6−0.4 (95% confidence limits; < 9.5 galaxies types ruled out at 7.2σ). This J-dropout Lyman break galaxy, named MACS0647-JD, was discovered as part Cluster Lensing and Supernova survey Hubble (CLASH). observe three magnified images this due strong gravitational lensing by cluster MACSJ0647.7+7015 0.591. The are factors ∼80, 7, 2, brighter two observed ∼26th magnitude AB (∼0.15 μJy) in...
Growing observational evidence now indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z~5-7 galaxies observed with Spitzer. This makes appear more massive, lower specific star formation rates. However, corrections for this have been very difficult to perform reliably due huge uncertainties overall strength such at z>~5.5. Here, we present most direct yet ubiquitous high-EW [OIII]+Hbeta in Lyman-break z~7, while also presenting strategy an...
The Sloan Digital Sky Survey has confirmed the existence of populations broad absorption line (BAL) quasars with various unusual properties. We present and discuss twenty-three such objects consider implications their wide range properties for models BAL outflows in general. have discovered one quasar a record number lines. Two other similarly complex many narrow troughs show MgII extending longward systemic host galaxy redshifts. This can be explained as an extended continuum source by...
We present the main results from our 940 ks observation of Chandra Deep Field-South using source catalog described in an accompanying paper by Giacconi et al. extend measurement number counts to 5.5 × 10-17 ergs cm-2 s-1 soft 0.5-2 keV band and 4.5 10-16 hard 2-10 band. The hard-band log N-log S shows a significant flattening (slope ≃0.6) below ≈10-14 s-1, leaving at most 10%-15% X-ray background be resolved, uncertainty lying total flux (XRB). On other hand, analysis very 5-10 reveals...
We analyze deep multicolor Advanced Camera images of the largest known gravitational lens, A1689. Radial and tangential arcs delineate critical curves in unprecedented detail, many small counterimages are found near center mass. construct a flexible light deflection field to predict appearance positions counterimages. The model is refined as new identified incorporated improve model, yielding total 106 30 multiply lensed background galaxies, spanning wide redshift range, 1.0 < z 5.5....
We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board Chandra X-Ray Observatory. The resulting X-ray spectrum, which covers 0.5-10 keV energy range, has best combination signal-to-noise ratio and resolution ever obtained for an AGN. This spectrum reveals absorption lines H-like He-like ions N, O, Ne, Mg, Al, Si, S. There are also possible Ar Ca as well C. identify inner-shell lower ionization such Si VII-Si XII S XII-S XIV. iron...
In the Chandra Deep Field-South 1 Ms exposure, we have found, at redshift 3.700 ± 0.005, most distant type 2 active galactic nucleus ever detected. It is source with hardest X-ray spectrum z > 3. The optical has no detected continuum emission to a 3 σ detection limit of ~3 × 10-19 ergs s-1 cm-2 Å-1 and shows narrow lines Lyα, C IV, N V, He II, O VI, [O III], III]. Their FWHM line widths range ~700-2300 km an average approximately ~1500 s-1. emitting gas metal-rich (Z ≃ 2.5-3 Z☉). 130 counts...
We present an empirical investigation of the colors quasars in Sloan Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625 with SDSS photometry: 1759 found during spectroscopic commissioning and follow-up observations on other telescopes, 50 matches to FIRST quasars, 573 from NASA Extragalactic Database, 243 two or more these sources. are distributed a 25 wide stripe centered celestial equator covering ∼529 deg2. Positions (accurate 02) magnitudes given for 898 known...
We present the analysis of faint galaxy population in Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676.These observations cover a total area 26.3 arcmin 2 , have depths close to that Hubble Deep Fields deepest part image, with 10σ detection limits point sources 27.8, 27.6 27.2 AB magnitudes g F 475W V 606W I 814W bands respectively.Measuring number count distribution is difficult task, different groups arriving at widely varying results even...
The Far Ultraviolet Spectroscopic Explorer (FUSE) has surveyed a large sample (>100) of active galactic nuclei (AGNs) in the low-redshift universe (z < 1). Its response at short wavelengths makes it possible to measure directly far-ultraviolet spectral properties quasi-stellar objects (QSOs) and Seyfert 1 galaxies z 0.3. Using archival FUSE spectra, we form composite extreme-ultraviolet (EUV) spectrum QSOs ≤ 0.67. After consideration many sources systematic error our analysis, find that...
We present F435W (B), F606W (broad V), and F814W I) coronagraphic images of the debris disk around β Pictoris obtained with Hubble Space Telescope's Advanced Camera for Surveys. These provide most photometrically accurate morphologically detailed views between 30 300 AU from star ever recorded in scattered light. confirm that previously reported warp inner is a distinct secondary inclined by ∼5° main disk. The projected spine coincides isophotal inflections, or "butterfly asymmetry," seen at...