A5003356726- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Science, Research, and Medicine
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Biotechnology and Related Fields
- Health and Medical Research Impacts
- Solar and Space Plasma Dynamics
- Nuclear and radioactivity studies
- Research, Science, and Academia
- Space exploration and regulation
- Adaptive optics and wavefront sensing
- Global Energy and Sustainability Research
- Nuclear Issues and Defense
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Astro and Planetary Science
- Biomedical Ethics and Regulation
- History and Developments in Astronomy
- Innovation Policy and R&D
- Pulsars and Gravitational Waves Research
Space Telescope Science Institute
2016-2025
Johns Hopkins University
2016-2025
Bloomberg (United States)
1996-2024
University of Baltimore
1987-2022
International Atomic Energy Agency
2006-2021
Unité de Recherche Agrosystèmes tropicaux
2017
Council of Science Editors
2011-2012
European Southern Observatory
1984-2007
Utrecht University
2006-2007
Trieste Astronomical Observatory
2002
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 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...
The Cosmic Evolution Survey (COSMOS) was initiated with an extensive allocation (590 orbits in Cycles 12-13) using the Hubble Space Telescope (HST) for high resolution imaging. Here we review characteristics of HST imaging Advanced Camera Surveys (ACS) and parallel observations NICMOS WFPC2. A square field (1.8$\sq$\deg) has been imaged single-orbit ACS I-F814W exposures 50% completeness sources 0.5\arcsec diameter at I$_{AB} $ = 26.0 mag. is a key part COSMOS survey, providing very...
▪ Abstract Considerable progress has been made over the past decade in study of evolutionary trends population galaxy clusters Universe. In this review we focus on observations X-ray band. surveys with ROSAT satellite, supplemented by follow-up studies ASCA and Beppo-SAX, have allowed an assessment evolution space density out to z ≈ 1 physical properties intracluster medium 0.5. With advent Chandra Newton-XMM their unprecedented sensitivity angular resolution, these extended beyond redshift...
At Science , we tend to get excited about new discoveries that lift the veil a little on how things work, from cells universe. That puts our focus firmly what has been added stock of knowledge. For this anniversary issue, decided shift frame reference, look instead
view Abstract Citations (519) References (58) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Disk-Halo Interaction: Superbubbles and the Structure of Interstellar Medium Norman, Colin A. ; Ikeuchi, Satoru Type II supernovae in our Galaxy are spatially temporally correlated consequences such correlations superbubbles supershells fed by tens or hundreds per bubble. These objects evolve expand rapidly, they soon break out disk Galaxy. collimated structures...
We present grids of massive star evolution models at four different metallicities (Z=0.004, 0.002, 0.001, 0.00001). The effects rotation on the stellar structure and transport angular momentum chemical elements through Spruit-Tayler dynamo rotationally induced instabilities are considered. After discussing uncertainties involved with adopted physics, we elaborate final fate stars as a function initial mass spin rate, each considered metallicity. In particular, investigate for which...
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...
view Abstract Citations (403) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Centrifugally driven winds from contracting molecular disks Pudritz, R. E. ; Norman, C. A. It is suggested that the bipolar outflows in dense clouds are associated with young stellar objects steady and centrifugally hydromagnetic arising which IR source embedded. Acceleration to supersonic speeds accomplished by magnetic field embedded disk extending outward beyond...
Observing more massive stars The number of that form at each mass is known as the initial function (IMF). For most masses, IMF follows a power-law distribution, first determined by Edwin Salpeter in 1955. Schneider et al. used observations nearby star-forming region 30 Doradus (also Tarantula Nebula) and combined these with stellar modeling to determine its IMF. They found above solar masses than predicted distribution. Because also have biggest influence on their surroundings—for instance,...
Star cluster formation in the early universe and their contribution to reionization remains date largely unconstrained. Here we present JWST/NIRCam imaging of most highly magnified galaxy known at z ~ 6, Sunrise arc. We identify six young massive star clusters (YMCs) with measured radii spanning 20 pc down 1 (corrected for lensing magnification), estimated stellar masses $10^{(6-7)}$ Msun, ages 1-30 Myr based on SED fitting photometry 8 filters extending rest-frame 7000A. The resulting mass...
Abstract Insights from JWST observations suggest that active galactic nuclei feedback evolved a short-lived, high-redshift phase in which radiatively cooled turbulence and/or momentum-conserving outflows stimulated vigorous early star formation (“positive” feedback), to late, energy-conserving depleted halo gas reservoirs and quenched formation. The transition between these two regimes occurred at z ∼ 6, independently of galaxy mass, for simple assumptions about the process. Observational...
Abstract We present JWST/NIRSpec prism spectroscopy of MACS0647−JD, a triply lensed z ∼ 11 candidate discovered in Hubble Space Telescope imaging and spatially resolved by JWST into two components, A B. Spectroscopy component yields spectroscopic redshift = 10.17 based on seven detected emission lines: C iii ] λ 1907, 1909, [O ii 3727, [Ne 3869, 3968, H δ 4101, γ 4340, 4363. These are the second-most distant detections these lines to date, galaxy observed just 460 million years after Big...
The thermodynamics of the diffuse, X-ray-emitting gas in clusters galaxies is determined by gravitational processes associated with infalling gas, shock heating and adiabatic compression, nongravitational such as supernovae, stellar winds, activity central galactic nuclei, radiative cooling. effect on intracluster medium (ICM) can be expressed terms ICM entropy. entropy a convenient variable long cooling negligible, since it remains constant during phase compression accretion into potential...
We present the X-ray luminosity function (XLF) of ROSAT Deep Cluster Survey sample over redshift range 0.05-0.8. Our results are derived from a complete flux-limited subsample 70 galaxy clusters, representing brightest half total sample, which have been spectroscopically identified down to flux limit 4×10−14 ergs m-2 s-1 (0.5-2.0 keV) and selected via serendipitous search in PSPC pointed observations. The baseline is large enough that evolutionary effects can be studied within sample. local...
view Abstract Citations (380) References (58) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Dissipation in Barred Galaxies: The Growth of Bulges and Central Mass Concentrations Pfenniger, Daniel ; Norman, Colin Basic dynamical mechanisms that produce an amplification the accretion rate gas clouds into central regions barred galaxies, their subsequent effects on evolution are discussed. Weakly dissipative orbits, representing clouds, computed a galaxy model...
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...
view Abstract Citations (378) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Bipolar Hydromagnetic Winds from Disks around Protostellar Objects Pudritz, R. E. ; Norman, C. A. The bipolar outflows associated with protostars are modeled as two-component, hydromagnetic winds which originate in the envelopes of rotating, magnetized molecular disks. authors show that torques exerted upon disks by centrifugally driven can account for both observed...
We analyze the ROSAT Deep Cluster Survey (RDCS) to derive cosmological constraints from evolution of cluster X-ray luminosity distribution. The sample contains 103 galaxy clusters out z ≃ 0.85 and flux limit Flim = 3 × 10-14 ergs s-1 cm-2 (RDCS-3) in [0.5-2.0] keV energy band, with a high-redshift extension containing four at 0.90 ≤ 1.26 brighter than 1 (RDCS-1). assume models be specified by matter density parameter Ωm, rms fluctuation amplitude 8 h-1 Mpc scale σ8, shape for cold dark...
view Abstract Citations (380) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Clumpy molecular clouds - A dynamic model self-consistently regulated by T Tauri star formation. Norman, C. ; Silk, J. is proposed which can account for the longevity, energetics, and dynamical structure of dark clouds. Recent observations a high space density stars in some provide basis assertion that high-velocity winds from these low mass pre-main-sequence...
view Abstract Citations (296) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Bar Dissolution and Bulge Formation: an Example of Secular Dynamical Evolution in Galaxies Norman, Colin A. ; Sellwood, J. Hasan, Hashima We discuss secular changes the stellar distribution a barred disk galaxy that may result from substantial inflows gas. present two- three-dimensional N-body simulations which we mimic build up gas at center after strong bar has...
view Abstract Citations (359) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Evolution of Starburst Galaxies to Active Galactic Nuclei Norman, Colin ; Scoville, Nick A model is proposed for active galactic nuclei in which a massive central star cluster builds up and feeds black hole as result mass loss during post-main-sequence stellar evolution. starting point the specific treated here coeval 4 x 10^9^ M_sun_ within ~10 pc, possibly...