Search

A main science goal for the Large Synoptic Survey Telescope (LSST) is to measure the cosmic shear signal from weak lensing to extreme accuracy. One difficulty, however, is that with the short exposure time ($\simeq$15 seconds) proposed, the spatial variation of the Point Spread Function (PSF) shapes may be dominated by the atmosphere, in addition to optics errors. While optics errors mainly cause the PSF to vary on angular scales similar or larger than a single CCD sensor, the atmosphere generates stochastic structures on a wide range of angular scales. It thus becomes a challenge to infer the multi-scale, complex atmospheric PSF patterns by interpolating the sparsely sampled stars in the field. In this paper we present a new method, PSFent, for interpolating the PSF shape parameters, based on reconstructing underlying shape parameter maps with a multi-scale maximum entropy algorithm. We demonstrate, using images from the LSST Photon Simulator, the performance of our approach relative to a 5th-order polynomial fit (representing the current standard) and a simple boxcar smoothing technique. Quantitatively, PSFent predicts more accurate PSF models in all scenarios and the residual PSF errors are spatially less correlated. This improvement in PSF interpolation leads to a factor of 3.5 lower systematic errors in the shear power spectrum on scales smaller than $\sim13'$, compared to polynomial fitting. We estimate that with PSFent and for stellar densities greater than $\simeq1/{\rm arcmin}^{2}$, the spurious shear correlation from PSF interpolation, after combining a complete 10-year dataset from LSST, is lower than the corresponding statistical uncertainties on the cosmic shear power spectrum, even under a conservative scenario.

The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image $\sim$ 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to $r\sim27.5$, with over 4 billion well measured galaxies. To take full advantage of this unprecedented statistical power, the systematic errors associated with weak lensing measurements need to be controlled to a level similar to the statistical errors. This work is the first attempt to quantitatively estimate the absolute level and statistical properties of the systematic errors on weak lensing shear measurements due to the most important physical effects in the LSST system via high fidelity ray-tracing simulations. We identify and isolate the different sources of algorithm-independent, \textit{additive} systematic errors on shear measurements for LSST and predict their impact on the final cosmic shear measurements using conventional weak lensing analysis techniques. We find that the main source of the errors comes from an inability to adequately characterise the atmospheric point spread function (PSF) due to its high frequency spatial variation on angular scales smaller than $\sim10'$ in the single short exposures, which propagates into a spurious shear correlation function at the $10^{-4}$--$10^{-3}$ level on these scales. With the large multi-epoch dataset that will be acquired by LSST, the stochastic errors average out, bringing the final spurious shear correlation function to a level very close to the statistical errors. Our results imply that the cosmological constraints from LSST will not be severely limited by these algorithm-independent, additive systematic effects.

We present laboratory spectra of dielectronic recombination (DR) satellite transitions attached to the He-like and H-like iron resonance lines obtained with the NASA Goddard Space Flight Center X-ray calorimeter and produced by a thermal plasma simu1ation technique on the EBIT-I electron beam ion trap at the Lawrence Livermore National Laboratory. We demonstrate that the calorimeter has sufficient spectral resolution in the 6-9 keV range to provide reliable measurements not only of standard DR satellite to resonance line intensities but also of DR satellite to DR satellite ratios that can be used to diagnose nonthermal electron distributions. Electron temperatures derived from the measured line intensities are consistent with the temperature of the simulated plasma. Temperature measurements based on DR satellite transitions have significant advantages over those based on collisional ionization equilibrium or continuum shape. Thus, successful demonstration of this method with the X-ray calorimeter is an important step fur its application in X-ray astronomy.

We present a large X-ray selected serendipitous cluster survey based on a novel joint analysis of archival Chandra and XMM-Newton data. The survey provides enough depth to reach clusters of flux of $\approx 10^{-14} {ergs} {cm}^{-2} {s}^{-1}$ near $z$ $\approx$ 1 and simultaneously a large enough sample to find evidence for the strong evolution of clusters expected from structure formation theory. We detected a total of 723 clusters of which 462 are newly discovered clusters with greater than 6$\sigma$ significance. In addition, we also detect and measure 261 previously-known clusters and groups that can be used to calibrate the survey. The survey exploits a technique which combines the exquisite Chandra imaging quality with the high throughput of the XMM-Newton telescopes using overlapping survey regions. A large fraction of the contamination from AGN point sources is mitigated by using this technique. This results in a higher sensitivity for finding clusters of galaxies with relatively few photons and a large part of our survey has a flux sensitivity between $10^{-14}$ and $10^{-15} {ergs} {cm}^{-2} {s}^{-1}$. The survey covers 41.2 square degrees of overlapping Chandra and XMM-Newton fields and 122.2 square degrees of non-overlapping Chandra data. We measure the log N-log S distribution and fit it with a redshift-dependent model characterized by a luminosity distribution proportional to $e^{-\frac{z}{z_0}}$. We find that $z_0$ to be in the range 0.7 to 1.3, indicative of rapid cluster evolution, as expected for cosmic structure formation using parameters appropriate to the concordance cosmological model., Comment: 16 pages, 26 figures, Accepted for publication in ApJ

In the history of astronomy, major advances in our understanding of the Universe have come from dramatic improvements in our ability to accurately measure astronomical quantities. Aided by rapid progress in information technology, current sky surveys are changing the way we view and study the Universe. Next-generation surveys will maintain this revolutionary progress. We focus here on the most ambitious survey currently planned in the visible band, the Large Synoptic Survey Telescope (LSST). LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: constraining dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. It will be a large, wide-field ground-based system designed to obtain multiple images covering the sky that is visible from Cerro Pachon in Northern Chile. The current baseline design, with an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg{sup 2} field of view, and a 3,200 Megapixel camera, will allow about 10,000 square degrees of sky to be covered using pairs of 15-second exposures in two photometric bands every three nights on average. The system is designed to yield high image quality, as well as superb astrometric and photometric accuracy. The survey area will include 30,000 deg{sup 2} with {delta} < +34.5{sup o}, and will be imaged multiple times in six bands, ugrizy, covering the wavelength range 320-1050 nm. About 90% of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 deg{sup 2} region about 1000 times in the six bands during the anticipated 10 years of operation. These data will result in databases including 10 billion galaxies and a similar number of stars, and will serve the majority of science programs. The remaining 10% of the observing time will be allocated to special programs such as Very Deep and Very Fast time domain surveys. We describe how the LSST science drivers led to these choices of system parameters.

Many astrophysical and laboratory plasmas possess Maxwell–Boltzmann (MB) electron energy distributions (EEDs). Interpreting or predicting the properties of these plasmas requires accurate knowledge of atomic processes such as radiative lifetimes, electron impact excitation and de-excitation, electron impact ionization, radiative recombination, dielectronic recombination, and charge transfer, all for thousands of levels or more. Plasma models cannot include all of the needed levels and atomic data. Hence, approximations need to be made to make the models tractable. Here we report on an “analog” technique we have developed for simulating a Maxwellian EED using an electron beam ion trap and review some recent results using this method. A subset of the atomic data needed for modeling Maxwellian plasmas relates to calculating the ionization balance. Accurate fractional abundance calculations for the different ionization stages of the various elements in the plasma are needed to reliably interpret or predict the properties of the gas. However, much of the atomic data needed for these calculations have not been generated using modern theoretical methods and are often highly suspect. Here we will also review our recent updating of the recommended atomic data for “digital’ computer simulations of MB plasmas in collisional ionization equilibrium (CIE), describe the changes relative to previously recommended CIE calculations, and discuss what further recombination and ionization data are needed to improve this latest set of recommended CIE calculations. PACS Nos.: 34.70.+e,34.80.Dp, 34.80.Kw, 34,80,Lx, 52.50.–j, 52.20.Fs, 52.20.Hv, 52.25.Jm, 52,72.+v, 52.75.–d, 95.30.Dr, 95.30.Ky, 98.38.Bn, 98.58.Bz

The focus of this report is on the opportunities enabled by the combination of LSST, Euclid and WFIRST, the optical surveys that will be an essential part of the next decade's astronomy. The sum of these surveys has the potential to be significantly greater than the contributions of the individual parts. As is detailed in this report, the combination of these surveys should give us multi-wavelength high-resolution images of galaxies and broadband data covering much of the stellar energy spectrum. These stellar and galactic data have the potential of yielding new insights into topics ranging from the formation history of the Milky Way to the mass of the neutrino. However, enabling the astronomy community to fully exploit this multi-instrument data set is a challenging technical task: for much of the science, we will need to combine the photometry across multiple wavelengths with varying spectral and spatial resolution. We identify some of the key science enabled by the combined surveys and the key technical challenges in achieving the synergies., Whitepaper developed at June 2014 U. Penn Workshop; 28 pages, 3 figures

We present a combined analysis of the X-ray emission of the Capella corona obtained with \textit{XMM-Newton} RGS, \textit{Chandra} HETGS, and LETGS. An improved atomic line database and a new differential emission measure (DEM) deconvolution method are developed for this purpose. Our new atomic database is based on the Astrophysical Plasma Emission Database and incorporates improved calculations of ionization equilibrium and line emissivities for L-shell ions of abundant elements using the Flexible Atomic Code. The new DEM deconvolution method uses a Markov Chain Monte-Carlo (MCMC) technique which differs from existing MCMC or $\chi^2$-fitting based methods. We analyze the advantages and disadvantages of each individual instrument in determining the DEM and elemental abundances. We conclude that results from either RGS or HETGS data alone are not robust enough due to their failure to constrain DEM in some temperature region or the lack of significant continuum emission in the wavelength band of the spectrometers, and that the combination of HETGS and RGS gives more stringent constraints on the DEM and abundance determinations. Using the LETGS data, we show that the recently discovered inconsistencies between the EUV and X-ray lines of Fe XVIII and XIX also exist in more highly charged iron ions, up to Fe XXIII, and that enhanced interstellar absorption due to partially ionized plasma along the Capella line of sight may explain some, but not all, of these discrepancies.

As part of a larger project to complete a comprehensive catalogue of astrophysically relevant emission lines in support of new-generation X-ray observatories using the Lawrence Livermore electron beam ion traps EBIT-I and EBIT-II, the authors present observations of sulfur lines in the soft X-ray and extreme ultraviolet regions. The database includes wavelength measurements with standard errors, relative intensities, and line assignments for 127 transitions of S VII through S XIV between 20 and 75 {angstrom}. The experimental data are complemented with a full set of calculations using the Hebrew University Lawrence Livermore Atomic Code (HULLAC). A comparison of the laboratory data with Chandra measurements of Procyon allows them to identify S VII-S XI lines.

The intensity ratios between 3 → 2 emission lines in Ni XIX were measured on the Livermore electron beam ion trap (EBIT-I) with a flat-field grating spectrometer and the NASA/Goddard Space Flight Center X-ray microcalo-rimeter. The results are consistent with earlier measurements of Fe XVII and other Ne-like ions at Livermore and confirm the problems in the atomic modeling of the direct collisional excitation for Ne-like systems.

We present results from the analysis of an XMM-Newton observation of the Seyfert 1 galaxy NGC 7469, the first high resolution X-ray spectrum of this source. The Reflection Grating Spectrometer (RGS) spectrum has several narrow absorption and emission lines of O, N, C and Ne, originating from gas at a range of ionisation parameters. from log xisimilar to1.6 to log xisimilar to-2 (where xi has the units erg cm s(-1)). We demonstrate that the ionisation state of the warm emitter is consistent with that of the high-ionisation phase of the warm absorber, and compare the warm absorber in this object with those in other sources. (C) 2004 Published by Elsevier Ltd on behalf of COSPAR.

A large number of galaxies, both normal and active, have been observed in ultraviolet light by the Optical Monitor on XMM-Newton. These are some of the deepest wide-field ultraviolet images of these galaxies yet obtained, and in many cases the first collected in this waveband. We present images of five active galaxies, and discuss the potential uses of the ultraviolet surface brightness distribution and morphology, in association with X-ray data, for Active Galactic Nuclei, star formation and galaxy evolution studies.

We present spatially resolved X-ray spectra taken with the EPIC cameras of XMM-Newton of a sample of 17 cooling clusters and three non-cooling clusters for comparison. The deprojected spectra are analyzed with a multi-temperature model, independent of any a priori assumptions about the physics behind the cooling and heating mechanisms. All cooling clusters show a central decrement of the average temperature, most of them of a factor of ~2. At each radius within the cooling region the gas is non-isothermal. The differential emission measure distribution peaks near the maximum (ambient) temperature, and steeply declines towards lower temperatures, proportional to T^3, or alternatively a cut-off at about a quarter to half of the maximum temperature. In general, we find a poor correlation between radio flux of the central galaxy and the temperature decrement of the cooling flow. This is interpreted as evidence that except for a few cases heating by a central AGN is not the most common cause of weak cooling flows. We investigate the role of heat conduction by electrons and find that the theoretically predicted conductivity rates are not high enough to balance radiation losses. The differential emission measure distribution has remarkable similarities with the predictions from coronal magnetic loop models. Also the physical processes involved (radiative cooling, thermal conduction along the loops, gravity) are similar for clusters loops and coronal loops. If coronal loop models apply to clusters, we find that a few hundred loops per scale height should be present. The typical loop sizes deduced from the observed emission measure distribution are consistent with the characteristic magnetic field sizes deduced from Faraday rotation measurements., Accepted for publication in Astronomy and Astrophysics, main journal, 25 pages, 12 figures

We have measured dielectronic recombination (DR) resonance strengths and energies for carbon-like Fe XXI forming Fe XX and for boron-like Fe XXII forming Fe XXI via N = 2 → N' = 2 core excitations. All measurements were carried out using the heavy-ion Test Storage Ring at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany. We have also calculated these resonance strengths and energies using three independent, state-of-the-art perturbative techniques: a multiconfiguration Breit-Pauli (MCBP) method using the code AUTOSTRUCTURE, a multiconfiguration Dirac-Fock (MCDF) method, and a relativistic configuration interaction method using the Flexible Atomic Code (FAC). Overall, reasonable agreement is found between our experimental results and our theoretical calculations. The most notable discrepancies tend to occur for relative collision energies 3 eV. We have used our measured 2 → 2 results to produce Maxwellian-averaged rate coefficients for Fe XXI and Fe XXII. Our experimentally derived rate coefficients are estimated to be accurate to better than ≈20% both for Fe XXI at kBTe > 0.5 eV and for Fe XXII at kBTe > 0.001 eV. For these results, we provide fits that are accurate to better than 0.5% for Fe XXI at 0.001 eV ≤ kBTe ≤ 10,000 eV and for Fe XXII at 0.02 eV kBTe ≤ 10,000 eV. Our fitted rate coefficients are suitable for ionization balance calculations involving Fe XXI and Fe XXII in photoionized plasmas. Previous published Burgess formula and LS-coupling calculations are in poor agreement with our experimentally derived rate coefficients. None of these published calculations reliably reproduce the magnitude or temperature dependence of our experimental results. Our previously published Fe XXI MCDF results are in good agreement with our experimental results for kBTe 0.07 eV. For both ions in this temperature range our new MCBP, MCDF, and FAC results are in excellent agreement with our experimentally derived rate coefficient.

We present an XMM-Newton observation of NGC 7469, including studies of the X-ray and UV variability, 0.2-10 keV spectral continuum, Fe K-alpha emission line and the first-ever high-resolution X-ray spectrum of the soft X-ray warm absorber. We compare the properties of this X-ray warm absorber with the UV warm absorber as seen in a FUSE observation one year previously. The 0.2-10 keV spectral continuum is best fitted by a power-law plus two blackbody model. An Fe K-alpha emission line is visible which consists of a single narrow component and is well-modelled by a simple gaussian. Narrow absorption and emission lines in the soft X-ray RGS spectrum demonstrate the existence of a multi-phase warm absorber with a range in log xi of ~ 2 to ~ -2 where xi is in erg cm s^-1. The warm absorber is blueshifted by several hundred km s^-1. The highest-ionisation phase of the absorber is the best constrained and has an overall equivalent Hydrogen column of order 10^20 cm^-2; we find that its ionisation parameter is consistent with that of the warm emitter which generates the narrow emission lines. We identify this high ionisation absorber with the low-velocity phase of the UV absorber observed by FUSE., Comment: 12 pages, 12 figures, accepted by A&A, a companion paper to "Multiwavelength studies of the Seyfert 1 galaxy NGC7469. I - Far UV observations with FUSE" by Kriss et al., astro-ph/0302552

We have measured resonance strengths and energies for dielectronic recombination (DR) of Fe XIX forming Fe XVIII via N = 2 → N' = 2 and N = 2 → N' = 3 core excitations. All measurements were carried out using the heavy-ion Test Storage Ring at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. We have also calculated these resonance strengths and energies using two independent, state-of-the-art techniques: the perturbative multiconfiguration Breit-Pauli (MCBP) and multiconfiguration Dirac-Fock (MCDF) methods. Overall, reasonable agreement is found between our experimental results and theoretical calculations. The most notable discrepancies are for the 3l3l' resonances. The calculated MCBP and MCDF resonance strengths for the n = 3 complex lie, respectively, ≈47% and ≈31% above the measured values. These discrepancies are larger than the estimated 20% total experimental uncertainty in our measurements. We have used our measured 2 → 2 and 2 → 3 results to produce a Maxwellian-averaged rate coefficient for DR of Fe XIX. Our experimentally derived rate coefficient is estimated to be good to better than ≈20% for kBTe ≥ 1 eV. Fe XIX is predicted to form in photoionized and collisionally ionized cosmic plasmas at kBTe 1 eV. Hence, our rate coefficient is suitable for use in ionization balance calculations of these plasmas. Previously published theoretical DR rate coefficients are in poor agreement with our experimental results. None of these published calculations reliably reproduce the magnitude or temperature dependence of the experimentally derived rate coefficient. Our MCBP and MCDF results agree with our experimental rate coefficient to within ≈20%.

The X-ray emission from the young supernova remnant (SNR) N103B is measured and analysed using the high-resolution cameras and spectrometers on board XMMM and CHANDRA. The spectrum from the entire remnant is reproduced very well with three plasma components of kT=0.55, 0.65, and 3.5 keV, corresponding roughly to line emission by the O-K, Fe-L, and Fe-K species, respectively. Narrow band images reveal different morphologies for each component. The kT=0.65keV component, which dominates the emission measure (4.5E65m^{-3}), is in ionisation equilibrium. This provides a lower limit of 3000 yrs to the age of the remnant, which is considerably older than the previously assumed age of the remnant (1500 yrs). Based on the measured energy of the Fe-K feature at 6.5 keV, the hot (3.5 keV) component is found to be recently shocked (~200 yrs) and still ionising. The high elemental abundances of O and Ne and the low abundance of Fe could imply that SNR N103B originated from a type II supernova (SN) rather than a type Ia SN as previously thought.

We have measured the resonance strengths and energies for dielectronic recombination (DR) of Fe XX forming Fe XIX via N=2 --> N'=2 (Delta_N=0) core excitations. We have also calculated the DR resonance strengths and energies using AUTOSTRUCTURE, HULLAC, MCDF, and R-matrix methods, four different state-of-the-art theoretical techniques. On average the theoretical resonance strengths agree to within ~30% which is significantly larger than the estimated relative experimental uncertainty of ~1 eV, which includes the predicted formation temperatures for Fe XX in an optically thin, low-density photoionized plasma with cosmic abundances, our experimental and theoretical results are in good agreement. We have also used our R-matrix results, topped off using AUTOSTRUCTURE for RR into J>=25 levels, to calculate the rate coefficient for RR of Fe XX. Our RR results are in good agreement with previously published calculations.

The luminous infrared-loud quasar IRAS 13349+2438 was observed with the XMM-Newton Observatory as part of the Performance Verification program. The spectrum obtained by the Reflection Grating Spectrometer (RGS) exhibits broad (v ~ 1400 km/s FWHM) absorption lines from highly ionized elements including hydrogen- and helium-like carbon, nitrogen, oxygen, and neon, and several iron L-shell ions (Fe XVII - XX). Also shown in the spectrum is the first astrophysical detection of a broad absorption feature around lambda = 16 - 17 Ang identified as an unresolved transition array (UTA) of 2p - 3d inner-shell absorption by iron M-shell ions in a much cooler medium; a feature that might be misidentified as an O VII edge when observed with moderate resolution spectrometers. No absorption edges are clearly detected in the spectrum. We demonstrate that the RGS spectrum of IRAS 13349+2438 exhibits absorption lines from at least two distinct regions, one of which is tentatively associated with the medium that produces the optical/UV reddening., 6 pages. Accepted for publication in Astronomy and Astrophysics Letters, XMM issue

In this letter we present the soft X-ray (5-35A) spectrum of the supernova remnant (SNR) IE 0102-72.3 in the Small Magellanic Cloud, acquired by the reflection grating spectrometer (RGS) aboard ESA's XMM-Newton Observatory. This extended-source X-ray spectrum of unprecedented spectral resolution (lambda/Delta(lambda) approx. 300) permits, for the first time, unabiguous identification and measurement of isolated emission lines and line complexes alike. The diagnostic power of performing spectroscopy using groups of emission lines from single ions is exemplified. In particular, the bright Lyman and helium series lines for light elements (C VI, O VII, O VIII, Ne IX, Ne X and possibly Mg XI & Mg XII) show peculiar ratios, where the values [1s - np] / [1s - (n + l)p] are systematically weaker than expected for electron impact excitation. These measured ratios resemble signatures of recombining or charge exchanging plasmas. We argue that charge exchange, given its large cross section and evidence for inhomogeneous media within the SNR, is a likely mechanism for the observed emission. Also. the well known temperature diagnostics G(T(sub e)) = (i + f)/r of helium- like triplets (O VII & Ne IX) indicate high temperatures, well above the maximum emission temperature T(sub m) for each ion, and consistent with a purely ionizing plasma. The density diagnostics R(n(sub e)) = f / i meanwhile, are consistent with the low density limit, as expected.

We present the first high resolution X-ray spectrum of the bright O4Ief supergiant star Zeta Puppis, obtained with the Reflection Grating Spectrometer on-board XMM-Newton. The spectrum exhibits bright emission lines of hydrogen-like and helium-like ions of nitrogen, oxygen, neon, magnesium, and silicon, as well as neon-like ions of iron. The lines are all significantly resolved, with characteristic velocity widths of order 1000-1500 km s^{-1}. The nitrogen lines are especially strong, and indicate that the shocked gas in the wind is mixed with CNO-burned material, as has been previously inferred for the atmosphere of this star from ultraviolet spectra. We find that the forbidden to intercombination line ratios within the helium-like triplets are anomalously low for N VI, O VII, and Ne IX. While this is sometimes indicative of high electron density, we show that in this case, it is instead caused by the intense ultraviolet radiation field of the star. We use this interpretation to derive constraints on the location of the X-ray emitting shocks within the wind that are consistent with current theoretical models for this system., 6 pages, 5figures, accepted for publication in A&A Letters XMM issue

We describe a technique for producing a Maxwell–Boltzmann electron energy distribution using an electron beam ion trap (EBIT). The technique was implemented on the Lawrence Livermore EBIT to simulate Maxwellian plasmas. We discuss technical and experimental issues related to these simulations. To verify the fidelity of the quasi-Maxwellian, we have measured line emission due to dielectronic recombination (DR) and electron impact excitation (EIE) of heliumlike neon, magnesium, and argon for a range of simulated electron temperatures. The ratio of DR to EIE lines in heliumlike ions is a well understood electron temperature diagnostic. The spectroscopically inferred quasi-Maxwellian temperatures are in excellent agreement with the simulated temperatures.

The spectra of highly ionized iron species between 7 and 9 A have been studied using data obtained at the Princeton Large Torus tokamak under plasma conditions similar to those present in solar and stellar flares. The wavelengths of many iron lines are measured with very high accuracy (λ/Δλ up to 4 × 104), along with several other lines in species such as He-like Al XII and Mg XI. Theoretical spectra that predict both the wavelength and the intensity of Fe emission lines are compared with the observed spectra and are used to make accurate line identifications. Virtually all the observed iron lines are found to arise from n = 4, 5, and 6 → 2 transitions in Fe XXI-XXIV, and many lines are identified for the first time. Several transitions are shown to have diagnostic applications, and a detailed analysis of the density sensitivity of Fe XXII lines is presented.

The 32 pixel laboratory microcalorimeter spectrometer built by the NASA/Goddard Space Flight Center (GSFC) is now an integral part of the spectroscopy suite used routinely by the electron beam ion trap and radiative properties group at the Lawrence Livermore National Laboratory. The second generation laboratory instrument, dubbed the XRS/EBIT, is nearly identical to the XRS instrument on the Suzaku X-ray Observatory, formerly Astro-E2. The detector array is from the same processed wafer and uses the same HgTe absorbers. It is being used to measure the photon emission from a variety of radiation sources. These include X-ray emission from laboratory simulated celestial sources, X-ray emission from highly charged ions of Au, and X-ray emission following charge exchange and radiative electron capture. The wide range of applications demonstrates the versatility of a high-resolution, high-efficiency low-temperature detector that is able to collect data continually with minimal operator servicing.

We are developing a novel phonon-mediated distributed-TES X-ray detector in which X-rays are absorbed in a large germanium or silicon crystal, and the energy is read out by four distributed TESs. This design takes advantage of existing TES technology while overcoming the difficulties of designing spatially large arrays. The sum of the four TES signals will yield energy resolution of E / δ E ∼ 1000 and the partitioning of energy between the four will yield position resolution of X / δ X and Y / δ Y ∼ 100 . These macropixels, with advances in multiplexing, could be close-packed into 30 × 30 arrays equivalent to imaging instruments of 10 megapixels or more. We report on our progress to date and discuss its application to galaxy cluster searches and studies of the Warm-Hot Interstellar Medium.

We present laboratory measurements of high-resolution spectra of iron Kα emission under transient ionization conditions similar to those that are believed to exist in stellar flares and young supernova remnants. Taking advantage of our high spectral resolution (λ/Δλ ≥ 2000), we identify a number of transitions that can serve as diagnostics of ionizing plasmas. By varying the excitation energy in the experiments, we constrain the effects of the electron distribution on these diagnostic lines. Using our measured line ratios, we deduce values for the ionization time, η = Net, in the plasma, which agree with the actual values to ~20% accuracy. This result gives us confidence to our ability to derive similar constraints on astrophysical plasmas from remote X-ray spectroscopic observations.

Future weak lensing surveys potentially hold the highest statistical power for constraining cosmological parameters compared to other cosmological probes. The statistical power of a weak lensing survey is determined by the sky coverage, the inverse of the noise in shear measurements, and the galaxy number density. The combination of the latter two factors is often expressed in terms of $n_{\rm eff}$ -- the "effective number density of galaxies used for weak lensing measurements". In this work, we estimate $n_{\rm eff}$ for the Large Synoptic Survey Telescope (LSST) project, the most powerful ground-based lensing survey planned for the next two decades. We investigate how the following factors affect the resulting $n_{\rm eff}$ of the survey with detailed simulations: (1) survey time, (2) shear measurement algorithm, (3) algorithm for combining multiple exposures, (4) inclusion of data from multiple filter bands, (5) redshift distribution of the galaxies, and (6) masking and blending. For the first time, we quantify in a general weak lensing analysis pipeline the sensitivity of $n_{\rm eff}$ to the above factors. We find that with current weak lensing algorithms, expected distributions of observing parameters, and all lensing data ($r$- and $i$-band, covering 18,000 degree$^{2}$ of sky) for LSST, $n_{\rm eff} \approx37$ arcmin$^{-2}$ before considering blending and masking, $n_{\rm eff} \approx31$ arcmin$^{-2}$ when rejecting seriously blended galaxies and $n_{\rm eff} \approx26$ arcmin$^{-2}$ when considering an additional 15% loss of galaxies due to masking. With future improvements in weak lensing algorithms, these values could be expected to increase by up to 20%. Throughout the paper, we also stress the ways in which $n_{\rm eff}$ depends on our ability to understand and control systematic effects in the measurements., 17 pages, 9 figures, 7 tables; accepted by MNRAS. Updated version (Oct 2014) contains correction to the intrinsic galaxy size distribution (Fig 1c). This results in small changes in Fig 1c, 1d, 6, 7, Tab 1, 2 and related numbers in the paper. Further updated version (Dec 2017) contain some clarification of the plots, and minor correction to Fig 5

Recent ASCA spectra exhibit discrepancies with the relative line intensities of various Fe XXIII and XXIV L-shell emission lines predicted by standard plasma emission codes. To address this issue, we have carried out a series of high-resolution, broadband measurements of Fe XXIV line emission using an electron beam ion trap facility. X-ray lines produced in the trap are detected and resolved using Bragg crystal spectrometers. We report measurements of 3 → 2 and 4 → 2 transitions, which result primarily from electron impact excitation. Overall, good agreement is found with distorted wave calculations.

Fluorescence of iron ions induced by an X-ray laser allows the relative oscillator strength for Fe xvii emission to be determined; it is found to differ by 3.6σ from the best quantum mechanical calculations, suggesting that the poor agreement between prediction and observations of the brightest Fe xvii line is rooted in the quality of the underlying atomic wavefunctions used in the models. The interpretation of some of the spectral data from the Chandra and XMM-Newton orbiting X-ray missions has been complicated by discrepancies between theory and observation involving the emission lines from the highly charged Fe16+ ion, also known as Fe XVII. Specifically, the intensity of the strongest Fe XVII line, one of the brightest X-ray emissions from galaxies and stars, is generally weaker than predicted. Sven Bernitt et al. report the results of laboratory experiments in which a target of iron ions was fluoresced with femtosecond X-ray pulses from a free-electron laser. They find a relative oscillator strength that differs by 3.6σ from the best quantum mechanical calculations, suggesting that the poor agreement is rooted in the calculations of the underlying atomic dynamics and that the current astrophysical models are not at fault. Highly charged iron (Fe16+, here referred to as Fe xvii) produces some of the brightest X-ray emission lines from hot astrophysical objects1, including galaxy clusters and stellar coronae, and it dominates the emission of the Sun at wavelengths near 15 angstroms. The Fe xvii spectrum is, however, poorly fitted by even the best astrophysical models. A particular problem has been that the intensity of the strongest Fe xvii line is generally weaker than predicted2,3. This has affected the interpretation of observations by the Chandra and XMM-Newton orbiting X-ray missions1, fuelling a continuing controversy over whether this discrepancy is caused by incomplete modelling of the plasma environment in these objects or by shortcomings in the treatment of the underlying atomic physics. Here we report the results of an experiment in which a target of iron ions was induced to fluoresce by subjecting it to femtosecond X-ray pulses from a free-electron laser4; our aim was to isolate a key aspect of the quantum mechanical description of the line emission. Surprisingly, we find a relative oscillator strength that is unexpectedly low, differing by 3.6σ from the best quantum mechanical calculations. Our measurements suggest that the poor agreement is rooted in the quality of the underlying atomic wavefunctions rather than in insufficient modelling of collisional processes.

Using a split-mirror setup attached to a Reaction Microscope at the Free electron LASer in Hamburg (FLASH) we traced as function of time the migration of a hydrogen atom in C2H4+ from one end of the molecule to the other by coincident CH+ + CH3+ fragment detection. In addition, the observed H3++C2H+ channel provides for the first time evidence for an isomerization-induced formation mechanism of H3+ molecules.

The immortalized human bronchial epithelial cell line, BEP2D, can become malignantly transformed following its irradiation with alpha particles. Exposed cells progress through a latent period of eight to ten weeks prior to exhibiting malignant properties. The molecular basis for this delay is unclear, however it is thought to involve a manifestation of genomic instability brought on by ionizing radiation. In this study we addressed whether the microsatellite mutator phenotype which arises in cells that lack mismatch repair function could have played a role in the radiation-induced transformation of BEP2D cells. Three cell lines, including BEP2D and two transformed clonal derivatives, H2BT2L and R30T1L, were examined for the presence of the microsatellite mutator phenotype using a selectable reporter system developed in our laboratory. This reporter system is based on the ability of stably transduced cells to restore the reading frame of a hygromycin B phosphotransferase transferase gene rendered out of frame by the insertion of a (CA)(13) repeat tract immediately downstream of the ATG start codon. The parental BEP2D cell line had a relatively low hygromycin B resistant colony formation frequency of 2.36 x 10(-4). This value was similar to the frequencies of two malignantly transformed derivatives H2BT2L (0.996 x 10(-4)) and R30T1L (1.87 x 10(-4)). We therefore conclude that the H2BT2L and R30T1L cell lines are not deficient in their hMSH2, hMLH1, hPMS2 or hMSH3 mismatch repair gene functions, and that other factors orchestrated the alpha particle induced malignant transformation of H2BT2L and R30T1L cells.

We report a technique for measuring the lifetimes of long-lived excited levels in highly charged ions that fall into the range from ${10}^{\mathrm{\ensuremath{-}}2}$ to ${10}^{\mathrm{\ensuremath{-}}7}$ sec, inaccessible to existing methods. Employing a fast-switching electron beam to produce and excite electrostatically trapped ions, lifetimes are determined by observing the fluorescent decay of metastable levels. A value of 90.5\ifmmode\pm\else\textpm\fi{}1.5 \ensuremath{\mu}sec is obtained for the 1s2s $^{3}$${\mathit{S}}_{1}$\ensuremath{\rightarrow}1${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$ transition in heliumlike neon, in good agreement with theoretical predictions of 91.1 and 92.0 \ensuremath{\mu}sec.

We have examined DNA from four human esophageal carcinoma cell lines and 50 primary esophageal carcinomas obtained from China, Italy, and France for amplification of the cyclin D1 gene. We also examined 36 of these 50 carcinomas for expression of the cyclin D1 and retinoblastoma (RB) proteins by immunohistochemistry. We found a 3- to 10-fold amplification of the cyclin D1 gene in 16 of the 50 (32%) tumors and in two of the four cell lines. Cyclin D1 protein was overexpressed in 12 of 13 tumors and the two cell lines that showed gene amplification when compared to normal controls. Studies on RB protein expression indicated that 6 of the 36 (17%) tumor samples examined and one cell line did not show detectable expression of this protein. The tumors and cell lines that had cyclin D1 gene amplification and overexpression exhibited normal levels of expression of RB protein. By contrast, the tumors and cell line that did not appear to express the RB protein did not show amplification of the cyclin D1 gene and expressed only low levels of the cyclin D1 protein (P = 0.03). These results suggest that the inhibitory effect of RB on cell cycle progression can be abrogated during tumor development either by loss of expression of the RB gene or by increased expression of the cyclin D1 gene.

Amplification of the chromosome 11q13 region occurs in several types of human cancer including esophageal, breast, lung, bladder and hepatocellular carcinoma (HCC). The gene cyclin D1 maps to this region in close proximity to two proto-oncogenes hst-1 and int-2. We previously demonstrated that cyclin D1 was not only amplified but also overexpressed in about 30% of human esophageal cancers. To investigate the role of cyclin D1 in human hepatocellular carcinoma (HCC), DNA from 30 HCC and 5 control liver tissues from Taiwan and also the HCC cells lines HepG2 and Hep3B, were examined for amplification of the cyclin D1 gene. A 3 to 20-fold amplification was found in 4 of the 30 (13%) HCC samples but not in any of the 5 control tissues or the 2 cell lines. Immunohistochemical analysis of cyclin D1 indicated overexpression of this protein in tumors that displayed gene amplification. Weak or negative staining was observed in the other HCC samples as well as in the control tissues and cell lines. These data suggest that increased expression of cyclin D1 may play an important role in the development of a subset of human HCC, perhaps by perturbing normal control of the cell cycle.

Using both the LLNL high-voltage electron beam ion trap, SuperEBIT, and its low-energy counterpart, EBIT-II, we are currently performing spectroscopic measurements with electron beam energies ranging from 150 eV to 150 keV on ions ranging from near neutral Ne to ions as highly charged as T180+. Our measurements span photon energies from visible light to hard X-rays and focus on electron-ion interaction cross sections, line identifications and QED measurements, the determination of nuclear parameters, the investigation of charge transfer reactions, and radiative transition rates. An overview of some of the new instrumentation and a subset of the current experiments is given.

International audience; We have used the EBIT Calorimeter Spectrometer (ECS), a microcalorimeter instrument built by the calorimeter group at the NASA/Goddard Space Flight Center, to make a variety of measurements since its installation at Lawrence Livermore National Laboratory's EBIT facility. These include measurements of charge exchange between neutral gas and K-and L-shell ions, measurements of the X-ray transmission efficiency of optical blocking filters, high resolution measurements of transition energies for high-Z, highly charged ions, and measurements of M and L-shell emission from highly charged tungsten following on earlier measurements of L-shell gold. Our results will see application in the interpretation of the spectra from the Jovian atmosphere and of the diffuse soft X-ray background, in tests of QED, and in diagnosing inertial and magnetic confinement fusion plasmas. These measurements augment previous laboratory astrophysics, atomic physics, and calibration measurements made using earlier versions of NASA's microcalorimeter spectrometer.

This paper describes the next generation X-ray observatory XEUS which has been submitted to the European Space Agency in the framework of the Cosmic Vision 2015-2025 competition and has been selected for an assessment study. The paper summarizes the scientific goals and instrumental concepts of the proposed X-ray telescope with 5 m2 effective area and angular resolution better than 5 arc sec.

The Large Synoptic Survey Telescope (LSST) will be a large, wide-field ground-based system designed to obtain, starting in 2015, multiple images of the sky that is visible from Cerro Pachon in Northern Chile. About 90% of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 deg$^2$ region about 1000 times during the anticipated 10 years of operations (distributed over six bands, $ugrizy$). Each 30-second long visit will deliver 5$\sigma$ depth for point sources of $r\sim24.5$ on average. The co-added map will be about 3 magnitudes deeper, and will include 10 billion galaxies and a similar number of stars. We discuss various measurements that will be automatically performed for these 20 billion sources, and how they can be used for classification and determination of source physical and other properties. We provide a few classification examples based on SDSS data, such as color classification of stars, color-spatial proximity search for wide-angle binary stars, orbital-color classification of asteroid families, and the recognition of main Galaxy components based on the distribution of stars in the position-metallicity-kinematics space. Guided by these examples, we anticipate that two grand classification challenges for LSST will be 1) rapid and robust classification of sources detected in difference images, and 2) {\it simultaneous} treatment of diverse astrometric and photometric time series measurements for an unprecedentedly large number of objects., Comment: Presented at the "Classification and Discovery in Large Astronomical Surveys" meeting, Ringberg Castle, 14-17 October, 2008

The X-ray transient 4U1543-47 was observed in 1983 by the EXOSAT observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). Two emission line features are resolved. A broad (FWHM ~2.7 keV) line at 5.9 keV is detected in the GSPC, which we interprete as a redshifted and broadened iron Kα line. The Une broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth (τ ≈ 5), or from Doppler and relativistic effects in the vicinity of a compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission line feature at 0.74 keV, which may be an iron L-transition complex. However, we find that such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral Oxygen. The continuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from a very cool plasma (kT = 0.84 keV) with large scattering depth (τ ≈ 27). The continuum spectrum is strikingly similar to that of black hole candidate LMC X-3.

We report in-flight status of the X-ray detectors on board the Suzaku observatory, the 5th X-ray astronomy satellite of Japan launched on July 10, 2005. Suzaku is equipped with two types of instruments: one is the X-ray imaging spectrometers (XISs) and the other is hard X-ray detector (HXD). XIS utilizes the X-ray CCD camera in combination with the grazing-incidence X-ray telescope. HXD is a non-imaging, hybrid detector utilizing Si PIN diodes and GSO/BGO phoswich counters. Suzaku takes a low-earth, circular orbit with an altitude of 560 km and an inclination of 31 deg. This means that Suzaku goes through the south atlantic anomaly about 1/3 of its revolutions. This has a large impact on the in-flight performance of XIS and HXD, which is reported in detail in the present paper.

We describe a novel Monte Carlo approach to both spectral fitting and spatial/spectral inversion of X-ray astronomy data, and illustrate its application in the analysis of observations of clusters of galaxies. The X-ray events are directly compared with simulations using multivariate generalizations of the Kolmogorov-Smirnov and the Cramer-von Mises statistic. We demonstrate this method in studying the soft X-ray spectra of cooling-flow clusters with the Reflection Grating Spectrometers (RGS) on the XMM-Newton observatory. We also show preliminary results on simultaneously inverting X-ray and interferometric microwave Sunyaev-Zeldovich cluster data using a Monte Carlo technique. Various techniques are applied to simulate radiative transfer effects, model spatially-resolved sources, and simulate instrument response. We then apply statistical tests in the multi-dimensional data space.

In preparation for the Supernova Survey of the Sloan Digital Sky Survey (SDSS) II, a proposed 3-year extension to the SDSS, we have conducted an early engineering and science run during the fall of 2004, which consisted of approximately 20 scheduled nights of repeated imaging of half of the southern equatorial stripe. Transient supernova-like events were detected in near real-time and photometric measurements were made in the five SDSS filter bandpasses with a cadence of {approx} 2 days. Candidate type Ia supernovae (SNe) were pre-selected based on their colors, light curve shape, and the properties of the host galaxy. Follow-up spectroscopic observations were performed with the Astrophysical Research Consortium 3.5m telescope and the 9.2m Hobby-Eberly Telescope to confirm their types and measure the redshifts. The 2004 campaign resulted in 22 spectroscopically confirmed SNe, which includes 16 type Ia, 5 type II, and 1 type Ib/c. These SN Ia will help fill in the sparsely sampled redshift interval of z = 0.05-0.35, the so-called ''redshift desert'', in the Hubble diagram. Detailed investigation of the spectral properties of these moderate-redshift SNe Ia will also provide a bridge between local SNe and high-redshift objects, and will help us understand the systematics for futuremore » cosmological applications that require high photometric precision. Finally, the large survey volume also provides the opportunity to select unusual supernovae for spectroscopic study that are poorly sampled in other surveys. We report on some of the early results from this program and discuss potential future applications.« less

Celestial objects are often home to complex, dynamic, intriguing environments. High‐resolution x‐ray spectra from these sources measured by satellites such as the Chandra, XMM‐Newton, the Solar Maximum Mission, and the soon‐to‐be‐launched Astro‐E2 provide a means for understanding the physics governing these sources. Especially rich is the x‐ray emission from L‐shell transitions in highly charged iron ions. This emission is the source of a variety of diagnostics whose utility lies in the accuracy of the atomic data employed to model the x‐ray spectra. The atomic data used to describe these diagnostics are generally provided by large theoretical calculations and benchmarked by laboratory data. In this paper we discuss laboratory measurements of Fe L‐shell x‐ray emission including wavelengths, relative and absolute excitation cross sections, and line ratios that provide diagnostics of temperature and density.

The mixing of atomic and macroscopic processes taking place in non‐terrestrial objects creates complex, dynamic, and intriguing environments. High resolution x‐ray spectra from these sources measured by satellites such as Chandra, XMM‐Newton, and the Solar Maximum Mission provide a means for understanding the physics governing these sources. Laboratory measurements of the atomic processes have proved crucial to the interpretation of these spectra. For example using the LLNL electron beam ion traps EBIT‐I & EBIT‐II a detailed study of the x‐ray spectrum of Fe XVII has been conducted addressing the large ratio predicted by theory compared to observations of considerably smaller values of the relative intensity of the 2p‐3d 1P1 resonant to the 3D1 intercombination line. The difference was often attributed to opacity effects. However, laboratory measurements in the optically thin limit agree with observations demonstrating that the prediction is too large and opacity need not be invoked. The laboratory result...

Mechanical properties of the nuclear envelope have implications for cell and nuclear architecture as well as gene regulation. Using isolated Xenopus oocyte nuclei, we have established swelling conditions that separate the intact nuclear envelope (membranes, pore complexes and underlying lamin filament network) from nucleoplasm and the majority of chromatin. Swelling proves reversible with addition of high molecular mass dextrans. Micropipette aspiration of swollen and unswollen nuclear envelopes is also reversible and yields a network elastic modulus, unaffected by nucleoplasm, that averages 25 mN/m. Compared to plasma membranes of cells, the nuclear envelope is much stiffer and more resilient. Our results suggest that the nuclear lamina forms a compressed network shell of interconnected rods that is extensible but limited in compressibility from the native state, thus acting as a 'molecular shock absorber'. In light of the conservation of B-type lamins in metazoan evolution, the mechanical properties determined in this investigation suggest physical mechanisms by which mutated lamins can either destabilize nuclear architecture or influence nuclear responses to mechanical signals in Emery-Dreifuss muscular dystrophy, cardiomyopathy, progeria syndromes (premature 'aging') and other laminopathies.

Recent measurements of the K‐shell and L‐shell x‐ray spectra of highly charged helium‐like and neonlike ions are presented that were performed on the Livermore electron beam ion traps and the Princeton tokamaks. These measurements provide new insights into collisional and indirect line formation processes, identifications of forbidden lines, and a new plasma line diagnostic of magnetic field strength.

In the past year a spare NASA/GSFC Astro-E microcalorimeter has been installed, tested, and run successfully on the electron beam ions traps EBIT-I and EBIT-II at the Lawrence Livermore National Laboratory. The microcalorimeter complements crystal and grating spectrometers already part of the LLNL ebit program making it possible to measure a broad bandwidth (∼0.3–10 keV) with moderate resolution while simultaneously measuring a narrow bandwidth (∼0.7–1.3 keV) with high resolution. An overview of recent work is presented including measurements by the microcalorimeter of absolute excitation cross sections. These results continue our effort to provide atomic data of high quality to be used as benchmarks for theoretical calculations and to be included in atomic data bases employed by spectral fitting packages used to interpret spectra obtained by XMM-Newton and the Chandra X-Ray Observatory.

We have recently deployed an XRS (the X-ray Spectrometer on the Astro-E mission) engineering model microcalorimeter at the electron beam ion traps (EBIT I/II) at Lawrence Livermore National Laboratory. The EBIT I/II can produce well defined astrophysically interesting plasmas for a wide range of plasma conditions. The XRS engineering model was mated with a 32 element XRS 6×6 microcalorimeter array and integrated into a laboratory cryostat. The system was then transported to the EBIT I/II and operated over the last year. The microcalorimeter array has a composite resolution of 8 eV at 1 keV and 11 eV at 6 keV. During the campaign, we performed a number of high resolution, broad band observations including: K and L shell Fe with single ionization energies from 1–8 keV, Maxwellian distributions of Fe with 〈kT〉=0.5–3 keV, non-equilibrium states of Fe with very fine time resolution for η=109−1012 s cm−3. The total observation time for the campaign was over 10 Ms and the analysis is ongoing. We will present her...