|
|
|
X-RAY SPECTRAL VARIATION OF CARINAE THROUGH THE 2003 X-RAY MINIMUM
XMM-Newton is also equipped with the Reflection Grating ..... Car is embedded in soft diffuse emission from the Carina Nebula, but its contribution to ..... of the Chandra point-spread function. This is equivalent to a ...
The X-Ray Spectrum of the Supernova Remnant 1E 0102-72.3
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. ...
Soft X-Ray Emission Lines from a Relativistic Accretion Disk in MCG -6-30-15 and Mrk 766
XMM-Newton Reflection Grating Spectrometer (RGS) spectra of the Narrow Line Seyfert 1 galaxies MCG -6-30-15 and Mrk 766 are physically and spectroscopically inconsistent with standard models comprising a power-law continuum ...
2009-11-05
We examine deep XMM-Newton Reflection Grating Spectrometer (RGS) observations of the X-ray luminous galaxy cluster A1835. For the first time in a galaxy cluster we place direct limits on turbulent broadening of the emission lines. This is possible because the coolest X-ray emitting gas in the cluster, which is responsible for the lines, occupies a small region within the core. The most conservative determination of the 90 per cent upper limit on line-of-sight, non-thermal, velocity broadening is 274 km/s, measured from the emission lines originating within 30 kpc radius. The ratio of turbulent to thermal energy density in the core is therefore less than 13 per cent. There are no emission lines in the spectrum showing evidence for gas below ~3.5 keV. We examine the quantity of gas as a function of temperature and place a limit of 140 Msun/yr (90 per cent) for gas cooling radiatively below 3.85 keV.
2000-11-01
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.
Advances of plasma diagnostics with high-resolution spectroscopy of stellar coronae
2005-04-06
X-ray emission from cool stars is an important tracer for stellar activity. The X-ray luminosity reflects different levels of activity and covers four orders of magnitude in stars of spectral types M-F. Low spectral resolution provided by X-ray observations of stellar coronae in the past allowed the determination of temperature distributions and elemental abundances making use of atomic databases (listing line emissivities and bremsstrahlung continuum for a given temperature structure). The new missions XMM-Newton and Chandra carry X-ray gratings providing sufficient spectral resolution to measure the fluxes of strategic emission lines. I describe the different approaches applicable to low-resolution and high-resolution spectra, especially focusing on the new grating spectra with X-ray lines. From only a few lines it is possible to determine plasma temperatures and associated densities, to check for any effects from resonant scattering, and to identify particular abundance anomalies. Line-based temperature- and density measurements represent only a fraction of the total plasma, but the pressure environment of different fractions can be probed simply by selection of specific lines. Selected results are presented covering all aspects of line-based analyses.
XMM-Newton Spectroscopy of the Starburst Dominated Ultra Luminous Infrared Galaxy NGC 6240
2005-05-02
We present new XMM-Newton observation of the Ultra Luminous Infrared Galaxy (ULIRG) NGC 6240. We analyze the reflecting grating spectrometer (RGS) data, and data from the other instruments, and find a starburst dominated 0.5-3 keV spectrum with global properties resembling those observed in M82 but with a much higher luminosity. We show that the starburst region can be divided into an outer zone, beyond a radius of about 2.1 kpc, with a gas temperature of about 10^7 K and a central region with temperatures in the range (2-6) x 10^7 K. The gas in the outer region emits most of the observed Oviii Lyman-alpha line and the gas in the inner region the emission lines of higher ionization ions, including a strong Fexxv line. We also identify a small inner part, very close to the active nuclei, with typical Seyfert 2 properties including a large amount of photoionized gas producing a strong Fe K-alpha 6.4 keV line. The combined abundance, temperature and emission measure analysis indicates super solar Ne/O, Mg/O, Si/O, S/O and possibly also Fe/O. The analysis suggests densities in the range of (0.07-0.28) x epsilon^(1/2) cm^(-3) and a total thermal gas mass of about 4 x 10^8 x epsilon^(1/2) solar masses, where epsilon is the volume filling factor. We used a simple model to argue that a massive starburst with an age of about 2 x 10^7 years can explain most of the observed properties of the source. NGC 6240 is perhaps the clearest case of an X-ray bright luminous AGN, in a merger, whose soft X-ray spectrum is dominated by a powerful starburst.
Cool X-ray emitting gas in the core of the Centaurus cluster of galaxies
2008-01-01
ABSTRACT We use a deep XMM-Newton Reflection Grating Spectrometer observation to examine the X-ray emission from the core of the Centaurus cluster of galaxies. We clearly detect Fe xvii emission at four separate wavelengths, indicating the presence of cool X-ray emitting gas in the core of the cluster. Fe ions from Fe xvii to xxiv are observed. The ratio of the Fe xvii 17.1 A lines to 15.0 A line and limits on O vii emission indicate a lowest detected temperature in the emitting region of 0.3 to 0.45 keV (3.5 to Formula Not Shown ). The cluster also exhibits strong N vii emission, making it apparent that the N abundance is supersolar in its very central regions. Comparison of the strength of the Fe xvii lines with a solar metallicity cooling flow model in the inner 17 kpc radius gives mass...
Statistical evaluation of the flux cross-calibration of the XMM-Newton EPIC cameras
2009-01-27
The second XMM-Newton serendipitous source catalogue, 2XMM, provides the ideal data base for performing a statistical evaluation of the flux cross-calibration of the XMM-Newton European Photon Imaging Cameras (EPIC). We aim to evaluate the status of the relative flux calibration of the EPIC cameras on board XMM-Newton (MOS1, MOS2, and pn) and investigate the dependence of the calibration on energy, position in the field of view of the X-ray detectors, and lifetime of the mission. We compiled the distribution of flux percentage differences for large samples of 'good quality' objects detected with at least two of the EPIC cameras. The mean offset of the fluxes and dispersion of the distributions was then found by Gaussian fitting. Count rate to flux conversion was performed with a fixed spectral model. The impact on the results of varying this model was investigated. Excellent agreement was found between the two EPIC MOS cameras to better than 4% from 0.2 keV to 12.0 keV. MOS cameras register 7-9% higher flux than pn below 4.5 keV and 10-13% flux excess above 4.5 keV. No evolution of the flux ratios is seen with time, except at energies below 0.5 keV, where we found a strong decrease in the MOS to pn flux ratio with time. This effect is known to be due to a gradually degrading MOS redistribution function. The flux ratios show some dependence on distance from the optical axis in the sense that the MOS to pn flux excess increases w ith off-axis angle. Furthermore, in the 4.5-12.0 keV band there is a strong dependence of the MOS to pn excess flux on the azimuthal-angle. These results strongly suggest that the calibration of the Reflection Grating Array (RGA) blocking factors is incorrect at high energies. Finally, we recommend ways to improve the calculation of fluxes in future versions of XMM-Newton source catalogues.
XMM-Newton revolutionizes the way we view the universe
2009-12-08
XMM-Newton, the most powerful X-ray observatory ever built and launched into space, marks its 10th anniversary on Dec. 10. XMM-Newton's observations have revolutionized the way we view the hottest and most extreme ...
High Resolution X-Ray Spectroscopy of SN 1987A: Monitoring with XMM-Newton
2010-02-10
We report the results of our XMM-Newton monitoring of SN 1987A. The ongoing propagation of the supernova blast wave through the inner circumstellar ring caused a drastic increase in X-ray luminosity during the last years, enabling detailed high resolution X-ray spectroscopy with the Reflection Grating Spectrometer. The observations can be used to follow the detailed evolution of the arising supernova remnant. The fluxes and broadening of the numerous emission lines seen in the dispersed spectra provide information on the evolution of the X-ray emitting plasma and its dynamics. These were analyzed in combination with the EPIC-pn spectra, which allow a precise determination of the higher temperature plasma. We modeled individual emission lines and fitted plasma emission models. Especially from the observations between 2003 and 2007 we can see a significant evolution of the plasma parameters and a deceleration of the radial velocity of the lower temperature plasma regions. We found an indication (3-sigma-level) of an iron K feature in the co-added EPIC-pn spectra. The comparison with Chandra grating observations in 2004 yields a clear temporal coherence of the spectral evolution and the sudden deceleration of the expansion velocity seen in X-ray images ~6100 days after the explosion.
A Multiwavelength Study of RZ Cassiopeiae: The XMM-Newton/VLA Campaign
2004-09-21
XMM-Newton and the VLA simultaneously observed the eclipsing Algol-type binary RZ Cassiopeiae in August 2003. The secondary eclipse (K3 IV companion behind the A3 V primary) was placed at the center of the 15-hour radio campaign, while the X-ray satellite monitored a full 1.2-day orbital period. We present results of the X-ray and radio campaigns. The X-ray light curve shows significant modulation probably related to rotational modulation and active region evolution, and even small flares. However, the X-ray eclipse is not deep, implying that the coronal X-ray emitting material is spatially extended. The Reflection Grating Spectrometer (RGS) spectrum shows a variety of bright emission lines from Fe, Ne, O, N. A strong [C/N] depletion probably reflects the surface composition of the secondary which fills its Roche lobe and loses material onto the primary. The O~\\textsc{vii} He-like triplet reflects a low forbidden-to-intercombination ratio; while it generally suggests high electron densities, the ratio is here modified by photoexcitation by the strong UV flux of the primary A3 V star. The radio light curve shows no similarity to the X-ray light curve. The eclipse timings are different, and the radio flux increased while the X-ray flux decreased. The radio spectral slope is shallow ($\\alpha = 0 - 1$).
XMM - Newton observations of Markarian 421
The BL Lac object Mrk 421 was observed on May 25, 2000 during the XMM - Newton CAL/PV phase. The high throughput of the X-ray telescopes and the spectral capabilities of the instruments allow an uninterrupted temporal and spectral study of the source with unprecedented time resolution. Mrk 421 was found at a relatively high state with a 2-6 keV flux of (1.3 - 1.9)E-10 erg cm**-2 s **-1. The observed intensity variations by more than a factor of three at highest X-ray energies are accompanied by complex spectral variations with only a small time lag (tau = 265 {+116} {-102} seconds) between the hard and soft photons. The (0.2-10) keV spectrum can be well fitted by a broken power law and no absorption structures are found in the source spectrum at the high spectral resolution of the transmission gratings.
XMM-Newton X-ray spectra of the SNR 0509-67.5: data and models
2008-07-04
We report on X-ray observations of the supernova remnant 0509-67.5 in the Large Magellanic Cloud with XMM-Newton X-ray observatory. We use the imaging spectroscopy (EPIC) and Reflective Grating Spectrometer (RGS) data to investigate properties of the remnant and its environment. The X-ray spectra were analyzed with SPEX software package. In addition to this we performed a numerical hydrodynamic simulation of the remnant. The EPIC data show prominent Fe K line emission, but the deduced overall amount of iron in the shocked ejecta is low. The data also show that the remnant has an asymmetric ejecta structure: the bright southwest region of the remnant shows an overabundance of metals. The analysis of the RGS spectrum shows that the remnant has a high lines velocity broadening of ~5000 km/s. We found a hydrodynamical model for the remnant with basic hydrodynamical and spectral parameters similar to the observed ones. The data analysis show that the reverse shock just recently reached iron layers of the ejecta. The brightness enhancement in the southwest region could be a sign of an asymmetric explosion or it could be the result of a density enhancement of the interstellar medium. We constructed numerical models which are in good agreement with the observations, with circumstellar density of 3e-25 g/cm^3, age of ~400 years, velocities of ~5000 km/s and an electron to ion temperature ratio of 0.01.
X-ray and UV observations of nova V598 Puppis between 147 and 255 days after outburst
2009-09-10
Aims: The launch of Swift has allowed many more novae to be observed regularly over the X-ray band. Such X-ray observations of novae can reveal ejecta shocks and the nuclear burning white dwarf, allowing estimates to be made of the ejecta velocity. Methods: We analyse XMM-Newton and Swift X-ray and UV observations of the nova V598 Pup, which was initially discovered in the XMM-Newton slew survey. These data were obtained between 147 and 255 days after the nova outburst, and are compared with the earlier, brighter slew detection. Results: The X-ray spectrum consists of a super-soft source, with the soft emission becoming hotter and much fainter between days ~147 and ~172 after the outburst, and a more slowly declining optically thin component, formed by shocks with kT ~ 200-800 eV (corresponding to velocities of 400-800 km s^-1). The main super-soft phase had a duration of less than 130 days. The Reflection Grating Spectrometer data show evidence of emission lines consistent with optically thin emission of kT ~100 eV and place a limit on the density of the surrounding medium of log(n_e/cm^-3) < 10.4 at the 90 % level. The UV emission is variable over short timescales and fades by at least one magnitude (at lambda ~ 2246-2600 angstrom) between days 169 and 255.
First high-resolution detection of a warm absorber in the Broad Line Radio Galaxy 3C 382
2009-07-03
Recent high-resolution measurements suggest that the soft X-ray spectrum of obscured Radio Galaxies (RG) exhibits signatures of photoionised gas (e.g. 3C 445 and 3C 33) similar to those observed in radio-quiet obscured Active Galactic Nuclei (AGN). While signatures of warm absorbing gas covering a wide range of temperature and ionisation states have been detected in about one half of the population on nearby Seyfert 1 galaxies, no traces of warm absorber gas have been discovered in the high-resolution spectra of Broad Line Radio Galaxies (BLRG). We present here the first detection of a soft X-ray warm absorber in the powerful FRII BLRG 3C 382 using the Reflection Grating Spectrometer (RGS) on-board XMM-Newton. The absorption gas appears to be highly ionised, with column density of the order of 10^{22} cm^{-2}, ionisation parameter log\\xi>2 erg cm^{-2} s^{-1} and outflow velocities of the order of 10^{3} km s^{-1}. The absorption lines may come from regions located outside the torus, however at distances less than 60 pc. This result may indicate that a plasma ejected at velocities near the speed of light and a photoionised gas with slower, outflow velocities can coexist in the same source beyond the Broad Line Regions.
Deep high-resolution X-ray spectra from cool-core clusters
2009-10-21
We examine deep XMM-Newton Reflection Grating Spectrometer (RGS) spectra from the cores of three X-ray bright cool core galaxy clusters, Abell 262, Abell 3581 and HCG 62. Each of the RGS spectra show Fe XVII emission lines indicating the presence of gas around 0.5 keV. There is no evidence for O VII emission which would imply gas at still cooler temperatures. The range in detected gas temperature in these objects is a factor of 3.7, 5.6 and 2 for Abell 262, Abell 3581 and HCG 62, respectively. The coolest detected gas only has a volume filling fraction of 6 and 3 per cent for Abell 262 and Abell 3581, but is likely to be volume filling in HCG 62. Chandra spatially resolved spectroscopy confirms the low volume filling fractions of the cool gas in Abell 262 and Abell 3581, indicating this cool gas exists as cold blobs. Any volume heating mechanism aiming to prevent cooling would overheat the surroundings of the cool gas by a factor of 4. If the gas is radiatively cooling below 0.5 keV, it is cooling at a rate at least an order of magnitude below that at higher temperatures in Abell 262 and Abell 3581 and two-orders of magnitude lower in HCG 62. The gas may be cooling non-radiatively through mixing in these cool blobs, where the energy released by cooling is emitted in the infrared. We find very good agreement between smooth particle inference modelling of the cluster and conventional spectral fitting. Comparing the temperature di stribution from this analysis with that expected in a cooling flow, there appears to be a even larger break below 0.5 keV as compared with previous empirical descriptions of the deviations of cooling flow models.
Cool X-ray emitting gas in the core of the Centaurus cluster of galaxies
2007-11-16
We use a deep XMM-Newton Reflection Grating Spectrometer observation to examine the X-ray emission from the core of the Centaurus cluster of galaxies. We clearly detect Fe-XVII emission at four separate wavelengths, indicating the presence of cool X-ray emitting gas in the core of the cluster. Fe ions from Fe-XVII to XXIV are observed. The ratio of the Fe-XVII 17.1A lines to 15.0A line and limits on O-VII emission indicate a lowest detected temperature in the emitting region of 0.3 to 0.45 keV (3.5 to 5.2x10^6 K). The cluster also exhibits strong N-VII emission, making it apparent that the N abundance is supersolar in its very central regions. Comparison of the strength of the Fe-XVII lines with a Solar metallicity cooling flow model in the inner 17 kpc radius gives mass deposition rates in the absence of heating of 1.6-3 Msun/yr. Spectral fitting implies an upper limit of 0.8 Msun/yr below 0.4 keV, 4 Msun/yr below 0.8 keV and 8 Msun/yr below 1.6 keV. The cluster contains X-ray emitting gas over at least the range of 0.35 to 3.7 keV, a factor of more than 10 in temperature. We find that the best fitting metallicity of the cooler components is smaller than the hotter ones, confirming that the apparent metallicity does decline within the inner 1 arcmin radius.
2010-08-23
Using the width of emission lines in XMM-Newton Reflection Grating Spectrometer spectra, we place direct constraints on the turbulent velocities of X-ray emitting medium in the cores of 62 galaxy clusters, groups and elliptical galaxies. We find five objects where we can place an upper limit on the line-of-sight broadening of 500 km/s (90 per cent confidence level), using a single thermal component model. Two other objects are lower than this limit when two thermal components are used. Half of the objects examined have an upper limit on the velocity broadening of less than 700 km/s. To look for objects which have significant turbulent broadening, we use Chandra spectral maps to compute the expected broadening caused by the spatial extent of the source. Comparing these with our observed results, we find that Klemola 44 has extra broadening at the level of 1500 km/s. RX J1347.5-1145 shows weak evidence for turbulent velocities at 800 km/s. In addition we obtain limits on turbulence for Zw3146, Abell 496, Abell 1795, Abell 2204 and HCG 62 of less than 200 km/s. After subtraction of the spatial contribution and including a 50 km/s systematic uncertainty, we find at least 15 sources with less than 20 per cent of the thermal energy density in turbulence.
An XMM-Newton Observation of Abell 2597
2005-01-17
We report on a 120 ks XMM-Newton observation of the galaxy cluster Abell 2597. Results from both the European Photon Imaging Camera (EPIC) and the Reflection Grating Spectrometer (RGS) are presented. From EPIC we obtain radial profiles of temperature, density and abundance, and use these to derive cooling time and entropy. We illustrate corrections to these profiles for projection and point spread function (PSF) effects. At the spatial resolution available to XMM-Newton, the temperature declines by around a factor of two in the central 150 kpc or so in radius, and the abundance increases from about one-fifth to over one-half solar. The cooling time is less than 10 Gyr inside a radius of 130 kpc. EPIC fits to the central region are consistent with a cooling flow of around 100 solar masses per year. Broad-band fits to the RGS spectra extracted from the central 2 arcmin are also consistent with a cooling flow of the same magnitude; with a preferred low-temperature cut-off of essentially zero. The data appear to suggest (albeit at low significance levels below formal detection limits) the presence of the important thermometer lines from Fe XVII at 15, 17 Angstrom rest wavelength, characteristic of gas at temperatures ~ 0.3 keV. The measured flux in each line is converted to a mass deposition estimate by comparison with a classical cooling flow model, and once again values at the level of 100 solar masses per year are obtained. These mass deposition rates, whilst lower than those of previous generations of X-ray observatories, are consistent with those obtained from UV data for this object. This raises the possibility of a classical cooling flow, at the level of around 100 solar masses per year, cooling from 4 keV by more than two orders of magnitude in temperature.
AGN/starburst connection in action: the half million second RGS spectrum of NGC1365
2009-08-04
We present a deep (~5.8 days) 0.3-2 keV high-resolution spectrum of NGC1365, collected with the reflection grating spectrometer (RGS) on board XMM-Newton. The spectrum is dominated by strong recombination lines of He- and H-like transitions from carbon to silicon, as well as by L transitions from FeXVII. The continuum is strong, especially in the 10 to 20 Angstrom, range. Formal fits require two optically thin, collisionally ionised plasma components, with temperatures ~300 and ~640 eV. However, they leave the bulk of the forbidden components of the He-alpha OVII and NVI triplets unaccounted for. These features can be explained as being produced by photoionised gas. NGC1365 is therefore the first obscured AGN, whose high-resolution X-ray spectrum requires both collisional ionisation and photoionisation. The relative weakness of photoionisation does not stem from the intrinsic weakness of its AGN, whose X-ray luminosity is ~10^{42} erg/s. We suggest that it may instead come from the line-of-sight from the active nucleus to the NLR being blocked by optically thick matter in the broad line region, at the same time responsible for the large observed variation of the column density obscuring the X-ray active nucleus. Alternatively, NGC1365 could host a remarkably luminous nuclear starburst when compared to the AGN accretion power [abriged].
2007-09-18
We analyse a 75ks XMM-Newton observation of PG 2112+059 performed in November 2005 and compare it with a 15ks XMM-Newton observation taken in May 2003. PG 2112+059 was found in a deep minimum state as its 0.2-12 keV flux decreased by a factor of 10 in comparison to the May 2003 observation. During the deep minimum state the spectra show strong emission in excess of the continuum in the 3-6 keV region. The excess emission corresponds to an EW = 26.1 keV whereas its shape resembles that of heavily absorbed objects. The spectra of both observations of PG 2112+059 can be explained statistically by a combination of two absorbers where one shows a high column density, $N_{H} \\sim 4.5 \\times 10^{23} cm^{-2}$, and the other high ionisation parameters. As the ionisation parameter of the high flux state, $\\xi \\sim 34 erg cm s^{-1}$, is lower than the value found for the deep minimum state, $\\xi \\sim 110 erg cm s^{-1}$, either the absorbers are physically different or the absorbing material is moving with respect to the X-ray source. The spectra can also be explained by a continuum plus X-ray ionised reflection on the accretion disk, seen behind a warm absorber. The ionisation parameter of the high state ($\\xi \\sim 5.6 erg cm s^{-1}$) is higher than the ionisation parameter of the deep minimum state ($\\xi \\sim 0.2 erg cm s^{-1}$), as expected for a stationary absorber. The values found for the ionisation parameters are in the range typica l for AGNs. The spectra observed during the deep minimum state are reflection dominated and show no continuum emission. These can be understood in the context of light bending near the supermassive black hole as predicted by Minutti and Fabian.
2009-02-25
We report optical B-band observations with the Large Binocular Telescope LBT of the isolated neutron star RBS1774. The stacked image with total exposure 2.5h reveals a candidate optical counterpart at mB = 26.96 +- 0.20 at position RA(2000) = 21:43:03.4, DEC(2000)} = +06:54:17:5, within the joint Chandra and XMM-Newton error circles. We analyse archival XMM-Newton observations and derive revised spectral and positional parameters. The predicted optical flux from the extrapolated X-ray spectrum is likely twice as high as reported before. The measured optical flux exceeds the extrapolated X-ray spectral flux by a factor ~40 (15 - 60 at 1sigma confidence). We interpret our detection and the spectral energy distribution as further evidence of a temperature structure over the neutron star's surface and present a pure thermal model reflecting both the SED and the pulsed fraction of the light curve.
XMM-Newton broad-band observations of NGC 7582: Nh variations and fading out of the active nucleus
2007-02-21
We present results from two XMM-Newton observations of the bright classical Seyfert 2 galaxy NGC 7582 taken four years apart (2001 May and 2005 April). We present the analysis of the high-resolution (0.3-1 keV) RGS and low-resolution (0.3-10 keV) EPIC spectroscopic data. A comparison with a 1998 BeppoSAX observation suggests that XMM-Newton caught the source in a `reflection-dominated' phase, measuring the lowest continuum flux level ever (F(2-10 keV) = 2.3 x 10^(-12) erg cm^-2 s^-1) in 2005. NGC 7582 therefore experienced a dramatic spectral transition most likely due to the partial switching-off of the nuclear activity. The XMM-Newton spectrum of the continuum emission is very complex. It can be well described by a model consisting of a combination of a heavily absorbed (Nh ~ 10^(24) cm^-2) power law and a pure reflection component both obscured by a column density of ~ 4 x 10^(22) cm^-2. Notably, we detect a significant increase by a factor of ~2 in the column density of the inner, thicker absorber covering the primary X-ray source between 2001 and 2005. The 2005 XMM-Newton spectra show the strongest Fe Kalpha emission line ever measured in this source. This is consistent with the line delayed time response to the decrease of the nuclear activity. Our analysis also reveals that the soft X-ray spectrum is dominated by emission lines from highly ionized metals. The detection of a narrow OVIII radiative recombination continuum suggests an origin in a photoionized plasma.
2009-01-01
The main AB pair of the nearby alpha Centauri triple system has one of the most extensive X-ray records of any cosmic object, stretching over 30 years. The primary, alpha Cen A (G2 V), is a near twin of the Sun, with a similarly soft (1-2 MK) corona. The secondary, alpha Cen B (K1 V), is more active than the Sun, with a generally harder coronal spectrum. Here, more than a decade of spatially resolved measurements from ROSAT, XMM-Newton, and Chandra are compared on a common basis, with careful attention to conversion factors that translate count rates of the different instruments into absolute energy fluxes. For the latter purpose, two epochs of Chandra transmission grating spectra, which fully resolve the binary, were modeled using a differential emission measure formalism. The aggregate time series suggests that alpha Cen B was near ...
HEASARC: XMM-Newton Data Analysis
Sep 3, 2010 ... ABOUT XMM-NEWTON, GOF SERVICES, WHAT'S NEW, CALIBRATION, RELATED SITES, GALLERY ... for creating model background spectra and images is now part of SAS. ... ( This is still in the process of registration with the IAU). ...
XMM-Newton observations of SN1987A
2006-09-18
(abridged) We report on XMM-Newton observations of SN1987A in the Large Magellanic Cloud. The large collecting area telescopes together with the European Photon Imaging Cameras (EPIC) provide X-ray spectra with unprecedented statistical quality and make it possible to investigate the spectral evolution during the brightening observed since the discovery in X-rays. High resolution spectra from the Reflection Grating Spectrometers yield a complementary view and allow us to perform more detailed investigations of prominent emission lines. The X-ray spectra were modeled with two-temperature emission components from a hot plasma in collisional ionization equilibrium and in non-equilibrium (NEI). We find a temperature for the equilibrium component of 0.24+/-0.02 keV in January 2000 and April 2001 which increased to 0.30+/-0.02 keV in May 2003 and also an indication for a temperature increase in the hot NEI component from \\~2 keV to ~3 keV. Emission line ratios inferred from the RGS spectra suggest temperatures as low as 100 eV and an increase in the ionization state of oxygen and neon consistent with the observed temperature increases. The fast readout of the EPIC-pn instrument yields X-ray fluxes free of CCD pile-up effects which we used to normalize pile-up corrections for the published Chandra fluxes. The corrected X-ray light curve of SN1987A in the 0.5-2.0 keV energy band is best represented by a linear increase up to about day 4000 after the explosion and an exponential rise afterwards until the last published Chandra observation on day 6716. Modeling the light curve by emission from the inner ring which is approximated by a circular torus a central density n_H = 1.15x10^4 cm^-3 is found. In this model the forward shock has just passed the center of the torus.
XMM-Newton observations of 4 luminous radio-quiet AGN, and the soft X-ray excess problem
2008-01-31
The nature and origin of the soft X-ray excess in radio quiet AGN is still an open issue. The interpretation in terms of thermal disc emission has been challanged by the discovery of the constancy of the effective temperature despite the wide range of Black Hole masses of the observed sources. Alternative models are reflection from ionized matter and absorption in a relativistically smeared wind. We analyzed XMM-Newton observations of four luminous radio quiet AGN with the aim of characterising their main properties and in particular the soft excess. Different spectral models for the soft excess were tried: thermal disc emission, Comptonization, ionized reflection, relativistically smeared winds. Comptonization of thermal emission and the smeared winds provide the best fits, but the other models also provide acceptable fits. All models, however, return parameters very similar from source to source, despite the large differences in luminosities, Black Hole masses and Eddington ratios. Moreover, the smeared wind model require very large smearing velocities. The UV to X-ray fluxes ratios are very different, but do not correlate with any other parameter. No fully satisfactory explanation for the soft X-ray excess is found. Better data, like e.g. observations in a broader energy band, are needed to make further progresses.
The column density towards LMC X-1
2009-12-21
We measure the neutral absorption towards the black hole X-ray binary system LMC X-1 from six archival soft X-ray spectra obtained with the gratings and/or CCD detectors on Chandra, XMM-Newton, and Swift. Four spectral models for the soft continuum have been investigated. While the powerlaw model may overestimate NH considerably, the others give consistent results. Taking the lower metalicity of the Large Magellanic Cloud into account, we find equivalent hydrogen column densities of N_H = (1.0-1.3)*10^22 cm^-2, with a systematic dependence on the orbital phase. This variation of the neutral absorption can nearly explain the orbital modulation of the soft X-ray flux recently detected with the All Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE).
The Properties and the Evolution of the Highly Ionized Gas in MR2251-178
2003-11-02
We present the first XMM-Newton observations of the radio-quiet quasar MR2251-178. We model the X-ray spectrum with two power laws, one at high energies with a slope of \\Gamma=1.6 and the other to model the soft excess with a slope of \\Gamma=2.9, both absorbed by at least two warm absorbers (WAs). The high-resolution grating spectrum shows emission lines from N VI, O VII, O VIII, Ne IX, and Ne X, as well as absorption lines from the low ionization ions O III, O IV, and O V. A study of the spectral variations in MR2251-178 over a period of 8.5 years yields that all X-ray observations can be fitted with the above model. Luminosity variations over timescales of years seem to correlate with the soft excess variations but not with the WA properties variations. The overall picture is that of a stratified WA that enters and disappears from the line-of-sight on timescales of several months. We also present the first FUSE spectrum of MR2251-178. The general characteristics of the UV and X-ray absorbers seem to be consistent.
THE PHOTOIONIZED ACCRETION DISK IN HER X-1
2009-01-01
We present an analysis of several high-resolution Chandra grating observations of the X-ray binary pulsar Her X-1. With a total exposure of 170 ks, the observations are separated by years and cover three combinations of orbital and superorbital phases. Our goal is to determine distinct properties of the photoionized emission and its dependence on phase-dependent variations of the continuum. We find that the continua can be described by a partial covering model which above 2 keV is consistent with recent results from Rossi X-Ray Timing Explorer studies and at low energies is consistent with recent XMM-Newton and BeppoSAX studies. Besides a power law with fixed index, an additional thermal blackbody of 114 eV is required to fit wavelengths above 12 A (approx1 keV). We find that likely all the variability is caused by highly variable absorption columns in the range ...
SAX J1808.4-3658: high resolution spectroscopy and decrease of pulsed fraction at low energies
2009-03-19
XMM-Newton observed the accreting millisecond pulsar SAX J1808.4-3658 during its 2008 outburst. We present timing and spectral analyses of this observation, in particular the first pulse profile study below 2 keV, and the high-resolution spectral analysis of this source during the outburst. Combined spectral and pulse profile analyses suggest the presence of a strong unpulsed source below 2 keV that strongly reduces the pulsed fraction and a hard pulsed component that generates markedly double peaked profiles at higher energies. We also studied the high-resolution grating spectrum of SAX J1808.4-3658, and found several absorption edges and Oxygen absorption lines with whom we infer, in a model independent way, the interstellar column densities of several elements in the direction of SAX J1808.4-3658.
A longer XMM-Newton look at I Zwicky 1: Distinct modes of X-ray spectral variability
2007-03-14
The short-term spectral variability of the narrow-line Seyfert 1 galaxy I Zwicky 1 (I Zw 1) as observed in an 85 ks XMM-Newton observation is discussed in detail. I Zw 1 shows distinct modes of variability prior to and after a flux dip in the broad-band light curve. Before the dip the variability can be described as arising from changes in shape and normalisation of the spectral components. Only changes in normalisation are manifested after the dip. The change in the mode of behaviour occurs on dynamically short timescales in I Zw 1. The data suggest that the accretion-disc corona in I Zw 1 could have two components that are co-existing. The first, a uniform, physically diffuse plasma responsible for the "typical'' long-term (e.g. years) behaviour; and a second compact, centrally located component causing the rapid flux and spectral changes. This compact component could be the base of a short or aborted jet as sometimes proposed for radio-quiet active galaxies. Modelling of the average and time-resolved rms spectra demonstrate that a blurred Compton-reflection model can describe the spectral variability if we allow for pivoting of the continuum component prior to the dip.
Broad iron L-line and X-ray reverberation in 1H0707-495
2009-10-05
A detailed analysis of a long XMM-Newton observation of the Narrow Line Seyfert 1 galaxy 1H0707-495 is presented, including spectral fitting, spectral variability and timing studies. The two main features in the spectrum are the drop at ~ 7 keV and a complex excess below 1 keV. These are well described by two broad, K and L, iron lines. Alternative models based on absorption, although they may fit the high energy drop, cannot account for the 1 keV complexity and the spectrum as a whole. Spectral variability shows that the spectrum is composed of at least two components, which are interpreted as a power-law dominating between 1-4 keV, and a reflection component outside this range. The high count rate at the iron L energies has enabled us to measure a significant soft lag of ~ 30 s between 0.3-1 and 1-4 keV, meaning that the direct hard emission leads the reflected emissions. We interpret the lag as a reverberation signal originating within a few gravitational radii of the black hole.
XMM-Newton Observations of A133: A Weak Shock Passing through the Cool Core
2004-01-01
We use XMM-Newton observations of the cluster of galaxies A133 to study the X-ray spectrum of the intracluster medium (ICM). We find a cold front to the southeast of the cluster core. From the pressure profile near the cold front, we derive an upper limit to the velocity of the core relative to the rest of the cluster of ~1.5\\mu G.
2010-05-20
We present the frequency resolved energy spectra (FRS) of the low-mass X-ray binary dipper XB 1323-619 during persistent emission in four different frequency bands using an archival XMM-Newton observation. FRS method helps to probe the inner zones of an accretion disk. We find that the FRS is well described by a single blackbody component with kT in a range 1.0-1.4 keV responsible for the source variability in the frequency ranges 0.002-0.04 Hz, and 0.07-0.3 Hz. We attribute this component to the accretion disk and possibly emission from an existing boundary layer supported by radiation pressure. The appearance of the blackbody component in the lower frequency ranges and disappearance towards the higher frequencies suggests that it may also be a disk-blackbody emission. We detect a different form of FRS for the higher frequency ranges 0.9-6 Hz and 8-30 Hz which is modeled best with a power-law and a Gaussian emission line at 6.4$^{+0.2}_{-0.3}$ keV with an equivalent width of 1.6$^{+0.4}_{-1.2}$ keV and 1.3$^{+0.7}_{-0.9}$ keV for the two frequency ranges, respectively. This iron fluorescence line detected in the higher frequency ranges of spectra shows the existence of reflection in this system within the inner disk regions. In addition, we find that the 0.9-6 Hz frequency band shows two QPO peaks at 1.4$^{+1.0}_{-0.2}$ Hz and 2.8$^{+0.2}_{-0.2}$ Hz at about 2.8-3.1 $\\sigma$ confidence level. These are consistent with the prev iously detected $\\sim$ 1 Hz QPO from this source (Jonker et al. 1999). We believe they relate to the reflection phenomenon. The emission from the reflection region, being a variable spectral component in this system, originates from the inner regions of the disk with a maximum size of 4.7$\\times 10^9$ cm and a minimum size of 1.6$\\times 10^8$ cm calculated using light travel time considerations and our frequency resolved spectra.
We have analyzed spectra of the Galactic black hole GX 339-4 obtained through simultaneous 76 ksec XMM-Newton/EPIC-pn and 9 ksec RXTE observations during a bright phase of its 2002-2003 outburst. An extremely skewed, relativistic Fe K-alpha emission line and ionized disk reflection spectrum are revealed in these spectra. Self-consistent models for the Fe K-alpha emission line profile and disk reflection spectrum rule-out an inner disk radius compatible with a Schwarzschild black hole at more than the 8 sigma level of confidence. The best-fit inner disk radius of 2-3 r_g suggests that GX 339-4 harbors a black hole with a > 0.8-0.9 (where r_g = GM/c^2 and a=cJ/GM^2, and assuming that reflection in the plunging region is relatively small). This confirms indications for black hole spin based on a Chandra spectrum obtained later in the outburst. The emission line and reflection spectrum also rule-out a standard power-law disk emissivity in GX 339-4; a broken power-law form with enhanced emissivity inside 6 r_g gives improved fits at more than the 8 sigma level of confidence. The extreme red wing of the line and steep emissivity require a centrally-concentrated source of hard X-rays which can strongly illuminate the inner disk. Hard X-ray emission from the base of a jet - enhanced by gravitational light bending effects - could create the concentrated hard X-ray emission; this process may be related to magnetic connections between the black hole and the inner disk. We discuss these results within the context of recent results from analyses of XTE J1650-500 and MCG -6-30-15, and models for the inner accretion flow environment around black holes.
On the peculiar properties of the narrow-line quasar PG 1543+489
2008-05-12
We present the analysis of four XMM-Newton observations of the narrow-line quasar PG 1543+489 at z=0.400 carried out over a rest-frame time-scale of about three years. The X-ray spectrum is characterized by a broad, relativistic iron K_alpha emission line and a steep photon index, which can be both explained by a ionized reflection model, where the source of X-ray photons is presumably very close to the black hole. If this were the case, strong light-bending effects are expected, and actually they provide the most plausible explanation for the large equivalent width (EW=3.1+/-0.8 keV in the source rest frame) of the iron line. Although the light-bending model provides a good description of the X-ray data of PG 1543+489, it is not possible to rule out an absorption model, where obscuring matter partially covers the X-ray source. However, the apparent lack of variations in the properties of the absorber over the time-scale probed by our observations may indicate that this model is less likely.
Broadband X-ray spectrum of the newly discovered broad line radio galaxy IGR J21247+5058
2007-09-13
In this paper we present radio and high energy observations of the INTEGRAL source IGR J21247+5058, a broad line emitting galaxy obscured by the Galactic plane. Archival VLA radio data indicate that IGR J21247+5058 can be classified as an FRII Broad Line Radio Galaxy. The spectrum between 610 MHz and 15 GHz is typical of synchrotron self-absorbed radiation with a peak at 8 GHz and a low energy turnover; the core fraction is 0.1 suggestive of a moderate Doppler boosting of the base of the jet. The high energy broad-band spectrum was obtained by combining XMM-Newton and Swift/XRT observation with INTEGRAL/IBIS data. The 0.4-100 keV spectrum is well described by a power law, with slope $\\Gamma$=1.5, characterised by complex absorption due to two layers of material partially covering the source and a high energy cut-off around 70-80 keV. Features such as a narrow iron line and a Compton reflection component, if present, are weak, suggesting that reprocessing of the power law photons in the accretion disk plays a negligible role in the source.
2009-01-01
ABSTRACT Iron emission lines at 6.4-6.97 keV, identified with fluorescent Ka transitions, are among the strongest discrete features in the X-ray band. These are therefore one of the most powerful probes to infer the properties of the plasma in the innermost part of the accretion disc around a compact object. In this paper, we present a recent XMM-Newton observation of the X-ray burster 4U 1705-44, where we clearly detect a relativistically smeared iron line at about 6.7 keV, testifying with high statistical significance that the line profile is distorted by high-velocity motion in the accretion disc. As expected from disc reflection models, we also find a significant absorption edge at about 8.3 keV; this feature appears to be smeared, and is compatible with being produced in the same regi...
XMM-Newton observation of the NLS1 Galaxy Ark 564: I. Spectral analysis of the time-average spectrum
2006-10-05
We use the data from a recent, 100 ksec XMM-Newton observation of the Narrow Line Seyfert 1 galaxy Ark 564 to obtain its time average, X-ray spectrum. The 3-11 keV spectrum is well fitted by a power-law of slope 2.43. We detect a weak (equivalent width ~80 eV) emission line at ~6.7 keV, which implies emission from ionized iron. There is no compelling evidence for significant broadening of the line.We also detect a possible Doppler shifted absorption line at 8.1 keV. At energies lower than 2 keV, the spectrum is dominated by a smooth soft excess component which can be well fitted either by a two black body components (kT~0.15 and 0.07 keV) or by a black body plus a relativistically blurred photoionized disc reflection model. We detect a broad, shallow flux deficit in the 0.65-0.85 keV band, reminiscent of the iron unresolved transition array (UTA) features. We do not detect neither a strong absorption edge around 0.7 keV nor an emission line around 1 keV. The soft excess emission is consistent with being reflected emission from a geometrically flat disc, with solar abundances, illuminated by an isotropic source. The weakness of the iron line emission can be explained by relativistic blurring. The UTA feature implies the presence of warm material with a column density of 2-5*10^{20} cm^{-2}. If the absorption line at 8.1 keV corresponds to FeXXVI Kalpha, it suggests the presence of a highly ionized absorbing material with N_H > 10^{23} cm^{-2}, outflowing at a high velocity of ~0.17c.
XMM-Newton Spectroscopy of the Highly Polarized and Luminous Broad Absorption Line Quasar CSO 755
2005-09-06
We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of ~3000 photons we find that this source has an X-ray continuum of `typical' radio-quiet quasars, with a photon index of Gamma=1.83^{+0.07}_{-0.06}, and a rather flat (X-ray bright) intrinsic optical-to-X-ray spectral slope of alpha_ox=-1.51. The source shows evidence for intrinsic absorption, and fitting the spectrum with a neutral-absorption model gives a column density of N_H~1.2x10^{22} cm^{-2}; this is among the lowest X-ray columns measured for BALQSOs. We do not detect, with high significance, any other absorption features in the X-ray spectrum. Upper limits we place on the rest-frame equivalent width of a neutral (ionized) Fe Ka line, <=180 eV (<=120 eV), and on the Compton-reflection component parameter, R<=0.2, suggest that most of the X-rays from the source are directly observed rather than being scattered or reflected; this is also supported by the relatively flat intrinsic alpha_ox we measure. The possibility that most of the X-ray flux is scattered due to the high level of UV-optical polarization is ruled out. Considering data for 46 BALQSOs from the literature, including CSO 755, we have found that the UV-optical continuum polarization level of BALQSOs is not correlated with any of their X-ray properties. A lack of significant short- and long-term X-ray flux variations in the source may be attributed to a large black-hole mass in CSO 755. We note that another luminous BALQSO, PG 2112+059, has both similar shallow C IV BALs and moderate X-ray absorption.
The soft X-ray and narrow-line emission of Mrk573 on kiloparcec scales
2010-09-10
We present a study of the circumnuclear region of the nearby Seyfert galaxy Mrk573 using Chandra, XMM-Newton and HST data. The X-ray morphology shows a biconical region extending up to 12 arcsecs (4 kpc) in projection from the nucleus. A strong correlation between the X-rays and the highly ionized gas seen in the [O III] image is reported. Moreover, we have studied the line intensities detected with the RGS/XMM-Newton and used them to fit the low resolution EPIC/XMM-Newton and ACIS/Chandra spectra. The RGS spectrum is dominated by emission lines of C VI, O VII, O VIII, Fe XVII, and Ne IX, among others. A good fit is obtained using these emission lines found in the RGS spectrum as a template for Chandra spectra of the nucleus and extended emission. The photoionization model Cloudy provides a reasonable fit for both the nuclear region and the cone-like structures. For the nucleus the emission is modelled using two phases: a high ionization [log(U)=1.23] and a low ionization [log(U)=0.13]. For the high ionization phase the transmitted and reflected component are in a ratio 1:2, whereas for the low ionization the reflected component dominates. For the extended emission, we successfully reproduced the emission with two phases. The first phase shows a higher ionization parameter for the NW (log(U)=0.9) than for the SE cone (log(U)=0.3). The second phase shows a low ionization parameter (log(U)=-3) and is rather uniform for NW and SE cones. In addition, the nuclear optical/infrared SED has been modeled by a clumpy torus model. The torus bolometric luminosity agrees with the AGN luminosity inferred from the observed hard X-ray spectrum. The optical depth along the line of sight derived from the SED fit indicates a high neutral column density in agreement with the classification of the nucleus as a Compton-thick AGN.
The X-ray spectrum of the newly discovered accreting millisecond pulsar IGR J17511-3057
ABSTRACT We report on a 70 ks XMM-Newton Target of Opportunity (ToO) observation of the newly discovered accreting millisecond pulsar, IGR J17511-3057. Pulsations at 244.8339512(1)Hz are observed throughout the outburst with an rms-pulsed fraction of 14.4(3) per cent. Pulsations have been used to derive a precise solution for the Porb = 12487.51(2) s binary system. The measured mass function indicates a main-sequence companion star with a mass between 0.15 and 0.44 Msolar. The XMM-Newton 0.5-11keV spectrum of IGR J17511-3057 can be modelled by at least three components, which we interpret, from the softest to the hardest, as multi-coloured disc emission, thermal emission from the neutron star surface and thermal Comptonization emission. Spectral fit of the XMM-Newton data and of the Rossi X-ray Timing Explorer (RXTE) data, taken in a simultaneous temporal window, well constrain the Comptonization parameters: the electron temperature, kTe = 51+6-4keV, is rather high, while the optical depth (? = 1.34+0.03-0.06) is moderate. The energy dependence of the pulsed fraction supports the interpretation of the cooler thermal component as coming from the accretion disc, and indicates that the Comptonizing plasma surrounds the hot spots on the neutron star surface, which in turn provides the seed photons. Signatures of reflection, such as a broadened iron K? emission line and a Compton hump at ~30keV, are also detected. We derive from the smearing of the reflection component an inner disc radius of >~40km for a 1.4 Msolar neutron star, and an inclination between 38 and 68. XMM-Newton also observed two type I X-ray bursts, whose fluence and recurrence time suggest that the bursts are ignited in a nearly pure helium environment. No photospheric radius expansion is observed, thus leading to an upper limit on the distance to the source of 10kpc. A lower limit of 6.5kpc can be also set if it is assumed that emission during the decaying part of the burst involves the whole neutron star surface. Pulsations are observed during the burst decay with an amplitude similar to the persistent emission. They are also compatible with being phase locked to pre-burst pulsations, suggesting that the location on the neutron star surface where they are formed does not change much during bursts.
2010-01-15
We report results from a 50 ks XMM-Newton observation of the dust-reddened broad-line quasar FTM 0830+3759 (z=0.413) selected from the FIRST/2MASS Red Quasar survey. For this AGN, a very short 9 ks Chandra exposure had suggested a feature-rich X-ray spectrum and HST images revealed a very disturbed host galaxy morphology. Contrary to classical, optically-selected quasars, the X-ray properties of red (i.e. with J-Ks> 1.7 and R-Ks> 4) broad line quasars are still quite unexplored, although there is a growing consensus that, due to moderate obscuration, these objects can offer a unique view of spectral components typically swamped by the AGN light in normal, blue quasars. The XMM-Newton observation discussed here has definitely confirmed the complexity of the X-ray spectrum revealing the presence of a cold (or mildly-ionized) absorber with Nh ~10^{22} cm^-2 along the line of sight to the nucleus and a Compton reflection component accompanied by an intense Fe K emission line in this quasar with a Lum(2-10) ~5 x 10^{44} erg/s. A soft-excess component is also required by the data. The match between the column density derived by our spectral analysis and that expected on the basis of reddening due to the dust suggests the possibility that both absorptions occur in the same medium. FTM 0830+3759 is characterized by an extinction/absorption-corrected X-ray-to-optical flux ratio alphaox = -2.3, that is steeper than expected on the basis of its UV luminosity. These findings indicate that the X-ray properties of FTM 0830+3759 differs from those typically observed for optically-selected broad line quasars with comparable hard X-ray luminosity.
Reflective diffraction grating
Reflective diffraction grating. A focused ion beam (FIB) micromilling apparatus is used to store color images in a durable medium by milling away portions of the surface of the medium to produce a reflective diffraction grating with blazed pits. The images are retrieved by exposing the surface of the grating to polychromatic light from a particular incident bearing and observing the light reflected by the surface from specified reception bearing.
XMMCOSMOS - XMM-Newton COSMOS X-Ray Point Source Catalog
May 5, 2010 ... A sequential unique identification number for each X-ray source in this ... by the choice of the spectral model to estimate the flux. The authors determined that by varying by Delta(Gamma) = 0.3 the spectral index Gamma ...
Swift, XMM-Newton satellites tune into a middleweight black hole
2009-11-10
While astronomers have studied lightweight and heavyweight black holes for decades, the evidence for black holes with intermediate masses has been much harder to come by. Now, astronomers at NASA's Goddard Space Flight ...
Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925
We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in the region of GRB 050925. This short Swift burst is a candidate for a newly discovered soft gamma-ray repeater (SGR) with the following observational ...
Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925
We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in the region of GRB 050925. This short Swift burst is a candidate for a newly discovered soft gamma-ray repeater (SGR) with the following observational ...
Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925
We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in the region of GRB 050925. This short Swift burst is a candidate for a newly discovered soft gamma-ray repeater (SGR) with the following ...
Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925
We present results from Swift, XMM-Newton, and deep INTEGRAL monitoring in the region of GRB 050925. This short Swift burst is a candidate for a newly discovered soft gamma-ray repeater (SGR) with the following observational ...
A FURTHER DROP INTO QUIESCENCE BY THE ECLIPSING NEUTRON STAR 4U 2129+47
2009-01-01
The low-mass X-ray binary 4U 2129+47 was discovered during a previous X-ray outburst phase and was classified as an accretion disk corona source. A 1% delay between two mid-eclipse epochs measured approx22 days apart was reported from two XMM-Newton observations taken in 2005, providing support to the previous suggestion that 4U 2129+47 might be in a hierarchical triple system. In this work, we present timing and spectral analysis of three recent XMM-Newton observations of 4U 2129+47, carried out between 2007 November and 2008 January. We found that except for the two 2005 XMM-Newton observations, all other observations are consistent with a linear ephemeris with a constant period of 18 857.63 s. However, we confirm the time delay reported for the two 2005 XMM-Newton observations. Compared to a Chandra observation taken in 2000, these new observations also ...
Metallic reflection grating under surface plasmon resonance condition
2004-01-01
The dispersion relation of surface plasmons and the photonic band gap of a metallic grating is determined by measurement of reflectance as a function of incident angle and wavelength. We have studied the dispersion relation of a sinusoidal grating and a rectangular grating. The behavior of the dispersion relation and band gap strongly depends on the grating profile and amplitude. Especially, higher Fourier components of the profile modify the surface-charge distribution associated with SP mode and energy
2010-09-16
Multi-epoch X-ray spectroscopy (0.3-25 keV) of the Seyfert 1.2 galaxy Mrk 79 (UGC 3973) spanning nearly eight years and a factor of three in broadband flux are analysed. The data are obtained at seven epochs with either XMM-Newton or Suzaku. Comparison with contemporaneous RXTE monitoring indicate that all flux states of Mrk 79 are represented by the data. The spectra are fitted in a self-consistent manner adopting a power law and ionised reflection to describe the broadband continuum. Modification of the spectra by a distant photoionised medium, seen predominantly in emission, are also included. Under the assumption that the inner disk is at the innermost stable circular orbit, our blurred reflection models give a spin of a = 0.7+/-0.1. The reflection component in each spectrum is weaker than predicted by simple reflection models. If the illuminating X-ray emission is produced by flares above the disk that move at mildly relativistic velocities, however, diminished reflection is expected. Light bending due to strong gravity near black holes can influence how the illuminating and reflected flux are observed; variations in Mrk 79 do not suggest that light bending is important in this source.
The disk-bearing young star IM Lup
2010-05-26
Classical T Tauri stars (CTTS) differ in their X-ray signatures from older pre-main sequence stars, e.g. weak-lined TTS (WTTS). CTTS show a soft excess and deviations from the low-density coronal limit in the He-like triplets. We test whether these features correlate with accretion or the presence of a disk by observing IM Lup, a disk-bearing object apparently in transition between CTTS and WTTS without obvious accretion. We analyse a Chandra grating spectrum and additional XMM-Newton data of IM Lup and accompanying optical spectra, some of them taken simultaneously to the X-ray observations. We fit the X-ray emission lines and decompose the Ha emission line in different components. In X-rays IM Lup has a bright and hot active corona, where elements of low first-ionisation potential are depleted. The He-like Ne IX triplet is in the low-density state, but due to the small number of counts a high-density scenario cannot be excluded on the 90% confidence level. In all X-ray properties IM Lup resembles a main-sequence star, but it is also compatible with CTTS signatures on the 90% confidence level, thus we cannot decide if the soft excess and deviations from the low-density coronal limit in the He-like triplets in CTTS require accretion or only the presence of a disk. IM Lup is chromospherically active, which explains most of the emission in Ha. Despite its low equivalent width, the complexity of the Ha line profile is reminiscent of CTTS. We present an estimate for the mass accretion rate of 10e-11 Msun/yr.
THE CYCLES OF {alpha} CENTAURI
The main AB pair of the nearby {alpha} Centauri triple system has one of the most extensive X-ray records of any cosmic object, stretching over 30 years. The primary, {alpha} Cen A (G2 V), is a near twin of the Sun, with a similarly soft (1-2 MK) corona. The secondary, {alpha} Cen B (K1 V), is more active than the Sun, with a generally harder coronal spectrum. Here, more than a decade of spatially resolved measurements from ROSAT, XMM-Newton, and Chandra are compared on a common basis, with careful attention to conversion factors that translate count rates of the different instruments into absolute energy fluxes. For the latter purpose, two epochs of Chandra transmission grating spectra, which fully resolve the binary, were modeled using a differential emission measure formalism. The aggregate time series suggests that {alpha} Cen B was near X-ray maximum in the mid-1990s, minimum in the late-1990s, then peaked again in 2004-2005, and more recently has been declining toward another minimum. Meanwhile, {alpha} Cen A showed minimal variability 1995-2000, and like the secondary presently is mired in an activity lull (in fact, as seen by XMM-Newton, the primary 'fainted' from view in the 2005 time frame). Comparisons between X-ray luminosities in the 0.2-2 keV (6-60 A) ROSAT 'WGACAT' band and a softer counterpart 0.06-1.2 keV (10-200 A) reinforce the idea that cycle depth is strongly dependent on the energy span of the measurement, and that much of the coronal luminosity of cool-corona objects like the Sun falls at longer wavelengths than are recorded efficiently by contemporary instruments. Consequently, one must be careful in discussing X-ray cycles, their amplitudes, and coronal heating requirements unless one can demonstrate good control over the out-of-band component.
Feedback through multiple outbursts in the cluster 2A 0335+096
2009-04-09
We examine the core of the X-ray bright galaxy cluster 2A 0335+096 using deep Chandra X-ray imaging and spatially-resolved spectroscopy, and include new radio observations. The set of around eight X-ray bright blobs in the core of the cluster, appearing like eggs in a bird's nest, contains multiphase gas from ~0.5 to 2 keV. The morphology of the coolest X-ray emitting gas at 0.5 keV temperature is similar to the Halpha emitting nebula known in this cluster, which surrounds the central galaxy. XMM-Newton grating spectra confirm the presence of material at these temperatures, showing excellent agreement with Chandra emission measures. On scales of 80 to 250 kpc there is a low temperature, high metallicity, swirl of intracluster medium as seen in other clusters. In the core we find evidence for a further three X-ray cavities, in addition to the two previously discovered. Enhancements in 1.5 GHz radio emission are correlated with the X-ray cavities. The total 4PV enthalpy associated with the cavities is around 5x10^59 erg. This energy would be enough to heat the cooling region for ~5x10^7 yr. We find a maximum pressure discontinuity of 26 per cent (2 sigma) across the surface brightness edge to the south-west of the cluster core. This corresponds to an upper limit on the Mach number of the cool core with respect to its surroundings of 0.55.
A self-consistent approach to the hard and soft states of 4U 1705-44
2010-04-13
We analyzed two XMM-Newton observations of the bright atoll source 4U 1705-44, which can be considered a prototype of the class of the persistent NS LMXBs showing both hard and soft states. The first observation was performed when the source was in a hard low flux state, the second during a soft, high-flux state. Both the spectra show broad iron emission lines. We fit the spectra using a two-component model, together with a reflection model specifically suited to the case of a neutron star, where the incident spectrum has a blackbody shape. In the soft state, the reflection model, convolved with a relativistic smearing component, consistently describes the broad features present in the spectrum, and we find a clear relation between the temperature of the incident flux and the temperature of the harder X-ray component that we interpret as the boundary layer emission. In this state we find converging evidence that the boundary layer outer radius is ~ 2 times the neutron star radius. In the low flux state, we observe a change in the continuum shape of the spectrum with respect to the soft state. Still, the broad local emission features can be associated with a disk reflecting matter, but in a lower ionization state, and possibly produced in an accretion disk truncated at greater distance. Our analysis provides strong evidence that the reflection component in soft states of LMXBs comes from to hard X-ray thermal irradiation, which we identify with the boundary layer emission, also present in the continuum model. In the hard state, the broad iron line if also produced by reflection, and the continuum disk emission can be self-consistently accounted if the disk is truncated at a greater distance than the soft state.
The broad-band X-ray spectrum of the Seyfert 1 galaxy, MCG+8-11-11
2010-07-12
We present a long (100 ks) Suzaku observation of one of the X-ray brightest AGN, MCG+8-11-11. These data were complemented with the 54-month Swift BAT spectrum, allowing us to perform a broad-band fit in the 0.6-150 keV range. The fits performed in the 0.6-10 keV band give consistent results with respect to a previous XMM-Newton observation, i.e. the lack of a soft excess, warm absorption along the line of sight, a large Compton reflection component (R~1) and the absence of a relativistic component of the neutral iron K$\\alpha$ emission line. However, when the PIN and Swift BAT data are included, the reflection amount drops significantly (R~0.2-0.3), and a relativistic iron line is required, the latter confirmed by a phenomenological analysis in a restricted energy band (3-10 keV). When a self-consistent model is applied to the whole broadband data, the observed reflection component appears to be all associated to the relativistic component of the iron K$\\alpha$ line. The resulting scenario, though strongly model-dependent, requires that all the reprocessing spectral components from Compton-thick material must be associated to the accretion disc, and no evidence for the classical pc-scale torus is found. The narrow core of the neutral iron K$\\alpha$ line is therefore produced in a Compton-thin material, like the BLR, similarly to what found in another Seyfert galaxy, NGC7213, but with the notable difference that MCG+8-11-11 pre sents spectral signatures from an accretion disc. The very low accretion rate of NGC7213 could explain the lack of relativistic signatures in its spectrum, but the absence of the torus in both sources is more difficult to explain, since their luminosities are comparable, and their accretion rates are completely different.
A long hard look at the minimum state of PG 2112+059 with XMM-Newton
2009-12-23
XMM-Newton successfully detected the minimum state of PG 2112+059 during a short snapshot observation and performed a long follow-up observation. The high signal-to-noise spectra are modelled assuming different emission scenarios and compared with archival spectra taken by XMM-Newton and Chandra. The PG 2112+059 X-ray spectra acquired in May 2007 allowed the detection of a weak iron fluorescent line, which is interpreted as being caused by reflection from neutral material at some distance from the primary X-ray emitting source. The X-ray spectra of PG 2112+059 taken at five different epochs during different flux states can be interpreted within two different scenarios. The first consists of two layers of ionised material with column densities of N_H ~5 x 10^22 cm^-2 and N_H ~3.5 x 10^23 cm^-2, respectively. The first layer is moderately ionised and its ionisation levels follow the flux changes, while the other layer is highly ionised and does not show any correlation with the flux of the source. The spectra can also be interpreted assuming reflection by an ionised accretion disk seen behind a warm absorber. The warm absorber ionisation is consistent with being correlated with the flux of the source, which provides an additional degree of self-consistency with the overall reflection-based model. We explain the spectral variability with light bending according to the models of Miniutti and Fabian and constrain the black hole spin to be a/M > 0.86. Both scenarios also assume that a distant cold reflector is responsible for the Fe K \\alpha emission line. Light bending provides an attractive explanation of the different states of PG 2112+059 and may also describe the physical cause of the observed properties of other X-ray weak quasars.
A Deep 0.3-10 keV Spectrum of the H$_{2}$O Maser Galaxy IC 2560
2008-01-17
We present a new XMM-Newton spectrum of the Seyfert 2 nucleus of IC 2560, which hosts H$_{2}$O maser emission from an inclined Keplerian accretion disk. The X-ray spectrum shows soft excess due to multi-temperature ionized plasma, a hard continuum and strong emission features, from Mg, Si, S, Ca, Fe and Ni, mainly due to fluorescence. It is consistent with reflection of the continuum from a mostly neutral medium and obscuration due to a high column density, $>$ 10$^{24}$ cm$^{-2}$. The amplitude of the reflected component may exceed 10% of the central unobscured luminosity. This is higher than the reflected fraction, of a few percent, observed in other Seyfert 2 sources like NGC 4945. We observe an emission line at 6.7 keV, possibly due to FeXXV, undetected in previous Chandra observations. The absorption column density associated with this line is less than 10$^{23}$ cm$^{-2}$, lower than the obscuration of the central source. We hypothesize that this highly ionized Fe line emission originates in warm gas, also responsible for a scattered component of continuum emission that may dominate the spectrum between 1 and 3 keV. We compare X-ray and maser emission characteristics of IC 2560 and other AGN that exhibit water maser emission originating in disk structures around central engines. The temperature for the region of the disk associated with maser action is consistent with the expected 400-1000K range. The clumpiness of disk s tructures (inferred from the maser distribution) may depend on the unobscured luminosities of the central engines.
2008-01-01
Instead of a conventional fixed multilayer grating, a self-suspended subwavelength grating (SSG) which consists of a single grating layer and possesses tunable functions, is investigated by the rigorous coupled-wave method in detail. Through optimizing various parameters including the incident wavelength, the grating period, the grating thickness and the grating filling factor, we demonstrate that the silicon dioxide (SiO2) SSG owns a narrow reflectance linewidth in the case of TE polarization. For the SiO2 SSG, the reflectance peak splits into two branches when the incident light deviates from normal incidence. In addition, the reflectance property of the SiO2 SSG with unoptimized parameters is also presented for comparison, which exhibits a much larger reflectance linewidth. It is expect...
X-ray Absorption and Reflection in Active Galactic Nuclei
2009-02-05
X-ray spectroscopy offers an opportunity to study the complex mixture of emitting and absorbing components in the circumnuclear regions of active galactic nuclei, and to learn about the accretion process that fuels AGN and the feedback of material to their host galaxies. We describe the spectral signatures that may be studied and review the X-ray spectra and spectral variability of active galaxies, concentrating on progress from recent Chandra, XMM-Newton and Suzaku data for local type 1 AGN. We describe the evidence for absorption covering a wide range of column densities, ionization and dynamics, and discuss the growing evidence for partial-covering absorption from data at energies > 10 keV. Such absorption can also explain the observed X-ray spectral curvature and variability in AGN at lower energies and is likely an important factor in shaping the observed properties of this class of source. Consideration of self-consistent models for local AGN indicates that X-ray spectra likely comprise a combination of absorption and reflection effects from material originating within a few light days of the black hole as well as on larger scales. It is likely that AGN X-ray spectra may be strongly affected by the presence of disk-wind outflows that are expected in systems with high accretion rates, and we describe models that attempt to predict the effects of radiative transfer through such winds, and discuss the prospects for new data to test and address these ideas.
The broad-band XMM-Newton and INTEGRAL spectra of bright type 1 Seyfert galaxies
2008-03-07
The 0.5-150 keV broad-band spectra of a sample of nine bright type 1 Seyfert galaxies are analyzed here. These sources have been discovered/detected by INTEGRAL and subsequently observed with XMM--Newton for the first time with high sensitivity below 10 keV. The sample, although small, is representative of the population of type 1 AGN which are now being observed above 20 keV. The intrinsic continuum has been modeled using three different parameterizations: a power-law model, an exponential cut-off power-law and an exponential cut-off power-law with a Compton reflection component. In each model the presence of intrinsic absorption, a soft component and emission line reprocessing features has also been tested. A simple power-law model is a statistically good description of most of the spectra presented here; an FeK line, fully and/or partial covering absorption and a soft spectral component are detected in the majority of the sample sources. The average photon index ( = 1.7 $\\pm$ 0.2) is consistent, within errors, with the canonical spectral slope often observed in AGN although the photon index distribution peaks in our case at flat Gamma (~ 1.5) values. For four sources, we find a significantly improved fit when the power-law is exponentially cut-off at an energy which is constrained to be below ~ 150 keV. The Compton reflection parameter could be estimated in only two objects of the sample and in both cases is found t o be R > 1.
Extreme flux states of NGC 4151 observed with INTEGRAL
2010-05-07
We present a comprehensive spectral analysis of all INTEGRAL data obtained so far for the X-ray-bright Seyfert galaxy NGC 4151. We also use all contemporaneous data from RXTE, XMM-Newton, Swift and Suzaku. We find a linear correlation between the medium and hard-energy X-ray fluxes measured by INTEGRAL, which indicates an almost constant spectral index over six years. The majority of INTEGRAL observations were made when the source was either at a very bright or very dim hard-X-ray state. We find that thermal Comptonization models applied to the bright state yields the plasma temperature of ~ 50-70 keV and its optical depth of ~ 1.3-2.6, depending on the assumed source geometry. For the dim state, these parameters are in the ranges of ~ 180-230 keV and ~ 0.3-0.7, respectively. The Compton parameter is y ~ 1 for all the spectra, indicating a stable geometry. Using this result, we can determine the reflection effective solid angles associated with the close and distant reprocessing media as ~ 0.3x2pi and 0.2x2pi, respectively. The plasma energy balance, the weak disc reflection and a comparison of the UV fluxes incident of the plasma to the observed ones are all consistent with an inner hot accretion surrounded by an outer cold disc. The disc truncation radius can be determined from an approximate equipartition between the observed UV and X-ray emission, and from the fitted disc blackbody model, as ~ 15 gravitational radii. Altern atively, our results can be explained by a mildly relativistic coronal outflow.
Extreme flux states of NGC 4151 observed with INTEGRAL
ABSTRACT We present a comprehensive spectral analysis of all INTEGRAL data obtained so far for the X-ray-bright Seyfert galaxy NGC 4151. We also use all contemporaneous data from RXTE, XMM-Newton, Swift and Suzaku. We find a linear correlation between the medium- and hard-energy X-ray fluxes measured by INTEGRAL, which indicates an almost constant spectral index over 6 yr. The majority of INTEGRAL observations were made when the source was either at a very bright or very dim hard-X-ray state. We find that thermal Comptonization models applied to the bright state yields the plasma temperature of ~=50-70keV and its optical depth of ~=1.3-2.6, depending on the assumed source geometry. For the dim state, these parameters are in the ranges of ~=180-230 keV and ~=0.3-0.7, respectively. The Compton parameter is for all the spectra, indicating a stable geometry. Using this result, we can determine the reflection effective solid angles associated with the close and distant reprocessing media as and , respectively. The plasma energy balance, the weak disc reflection and a comparison of the UV fluxes illuminating the plasma to the observed ones are all consistent with an inner hot accretion surrounded by an outer cold disc. The disc truncation radius can be determined from an approximate equipartition between the observed UV and X-ray emission, and from the fitted disc blackbody model, as ~15 gravitational radii. Alternatively, our results can be explained by a mildly relativistic coronal outflow. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland and Spain), the Czech Republic and Poland and with participation of Russia and the US. E-mail: lubinski@ncac.torun.pl (PL); aaz@camk.edu.pl (AAZ)
Laser induced damage in multilayer dielectric gratings due to ultrashort laser pulses
Chirped pulse amplification is increasingly used to produce intense ultrashort laser pulses. When high-efficiency gratings are the dispersive element, as in the LLNL Petawatt laser, their susceptibility to laser induced damage constitutes a limitation on the peak intensities that can be reached. To obtain robust gratings, it is necessary to understand the causes of short-pulse damage, and to recognize the range of design options for high efficiency gratings. Metal gratings owe their high efficiency to their high conductivity. To avoid the inevitable light absorption that accompanies conductivity, we have developed designs for high efficiency reflection gratings that use only transparent dielectric materials. These combine the reflectivity of a multilayer dielectric stack with a diffraction grating. We report here our present understanding of short-pulse laser induced damage, as it applies to dielectric gratings.
We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)
The objectives of the project are to investigate the use of (1) ultrasonic diffraction grating spectroscopy (UDGS) to measure the velocity of sound in a liquid or slurry and the particle size of a slurry and (2) shear wave reflection techniques to measure the viscosity of a slurry.
X-ray reverberation in 1H0707-495 revisited
2010-06-28
The narrow-line Seyfert 1 galaxy 1H0707-495 has previously been identified as showing time lags between flux variations in the soft- (0.3-1 keV) and medium-energy (1-4 keV) X-ray bands that oscillate between positive and negative values as a function of the frequency of the mode of variation. Here we measure and analyse the lags also between a harder X-ray band (4-7.5 keV) and the soft and medium bands, using existing XMM-Newton data, and demonstrate that the entire spectrum of lags, considering both the full energy range, 0.3-7.5 keV, and the full frequency range, 10^-5 < nu < 10^-2 Hz, are inconsistent with previous claims of arising as reverberation associated with the inner accretion disk. Instead we demonstrate that a simple reverberation model, in which scattering or reflection is present in all X-ray bands, explains the full set of lags without requiring any ad hoc explanation for the time lag sign changes. The range of time delays required to explain the observed lags extends up to about 1800 s in the hard band. The results are consistent with reverberation caused by scattering of X-rays passing through an absorbing medium whose opacity decreases with increasing energy and that partially-covers the source. A high covering factor of absorbing and scattering circumnuclear material is inferred.
Radiation of Accretion Discs in Strong Gravity
2004-11-22
In this thesis a computational tool for modelling spectral features of X-ray sources in a strong gravitational field is developed. Six transfer functions, the gravitational and Doppler shift, lensing, emission angle, relative time delay, change of the polarization angle and azimuthal emission angle, have been computed for light rays emitted from the equatorial plane of the Kerr black hole and received by an observer at infinity. The values of these functions for different angular momenta of the black hole and inclination angles of the observer in Kerr ingoing coordinates have been stored in the form of tables in a FITS file. Graphical representations of the results are shown as an atlas of contour figures of these functions. For the modelling of the spectra of an accretion disc, several general relativistic codes have been developed. Some of them can be used inside a more general spectral fitting package XSPEC for routine fitting of the data measured by X-ray satellites. These are the models for the relativistic emission lines, Compton reflection and for the general use as a relativistic extension of existing models (convolution models). Other components of the tool have extended features for studying non-stationary emission from accretion discs and polarimetry. The newly developed codes have been employed in several applications: data from XMM-Newton observations of Seyfert galaxy MCG-6-30-15 have been fitted, emission from an X-ray illuminated spot orbiting near a black hole was simulated, and polarization from an accretion disc illuminated by a primary source located above the black hole was computed.
Looking into the inner black hole accretion disc with relativistic models of iron line
We discuss black hole spin measurements employing the relativistic iron line profiles in the X-ray domain. We investigate the iron line band for two representative sources -- MCG -6-30-15 (active galaxy) and GX 339-4 (X-ray binary). We compare two models of the broad iron line, LAOR and KYRLINE. We realise that the spin is currently determined entirely from the position of the marginally stable orbit while the effect of the spin on the overall line shape would be resolvable with higher resolution X-ray missions. We show that the precision of the spin measurements depends on an unknown angular distribution of the disc emission. We study how sensitive the spin determination is to the assumptions about the intrinsic angular distribution of the emitted photons. We find that the uncertainty of the directional emission distribution translates to 20% uncertainty in the determination of the radius of marginally stable orbit. We perform radiation transfer computations of an X-ray irradiated disc atmosphere (NOAR code) to determine the directionality of outgoing X-rays in the 2-10 keV energy band. Based on these computations, we find that from the simple formulae for the directionality, the isotropic case reproduces the simulated data with the best accuracy. The most frequently used limb-darkening law favours higher values of spin and, in addition, a steeper radial emissivity profile. Furthermore, we present a spectral analysis of an XMM -Newton observation of a Seyfert 1.5 galaxy IRAS 05078+1626 being the first X-ray spectroscopic study of this source. The lack of the significant relativistic blurring of the reflection model component suggests the accretion disc to be truncated at a farther radius.
IGR J16351-5806: another close by Compton-thick AGN
2009-01-16
IGR J16351-5806 has been associated with the Seyfert 2 galaxy ESO 137-G34, having been first reported as a high energy emitter in the third INTEGRAL/IBIS survey. Using a new diagnostic tool based on X-ray column density measurements vs softness ratios, Malizia et al. (2007) identified this source as a candidate Compton thick AGN. In the present work we have analysed combined XMM-Newton and INTEGRAL data of IGR J16351-5806 in order to study its broad band spectrum and investigate its Compton thick nature. The prominent K_alpha fluorescence line around 6.4 keV (EW > 1 keV) together with a flat 2-10 keV spectrum immediately point to a highly obscured source. The overall spectrum can be interpreted in terms of a transmission scenario where some of the high energy radiation is able to penetrate through the thick absorption but a good fit is also obtained using a pure reflection spectrum. An alternative possibility is that of a complex absorption, where two layers of absorbing matter each partially covering the central nucleus are present in IGR J16351-5806. All three scenarios are compatible from a statistical viewpoint and provide reasonable AGN spectral parameters; more importantly all point to a source with an absorbing column greater than 1.5 x 10^24 cm^-2, i.e. to a Compton thick AGN. Because of this heavy obscuration, some extra components which would otherwise be hidden are able to emerge at low energies and can be studied. B y providing strong evidence for the Compton thick nature of IGR J16351-5806, we indirectly confirm the validity of the Malizia et al. diagnostic diagram.
Hunting high and low: XMM monitoring of the eclipsing polar HU Aquarii
2009-02-02
We want to study the temporal and spectral behaviour of HU Aqr in the X-ray domain during different accretion states. We obtained spectra and light curves from four different XMM-Newton pointings covering intermediate and low states. The X-ray observations were accompanied with high time resolution photometry obtained with the Optima and ULTRACAM instruments. On two occasions in May 2002 and 2003 HU Aqr was found in an intermediate state with the accretion rate reduced by a factor of 50 compared to earlier high state measurements. X-ray spectra in the intermediate state can be described by a model containing a blackbody component and hot thermal plasma. Contrary to the high state the ratio between soft and hard X-ray flux is nearly balanced. In agreement with previous measurements we observed a migration of the accretion spot and stream towards the line connecting both stars. The brightness of HU Aqr was further reduced by a factor of 80 during two low states in October 2003 and May 2005, where it was detected at a luminosity of only L_X = 4.7 * 10^(28) erg/sec . This luminosity would fit well with an active coronal emitter, but the relatively high plasma temperatures of 3.5 and 2.0 keV are more compatible with residual accretion. We updated the eclipse ephemeris of HU Aqr based on the eclipse egress of the accretion spot measured in various wavelength bands. The (O-C)-diagram of the observed accretion spot eclipse timings reve als complex deviations from a linear trend, which can be explained by a constant or cyclic period change or a combination thereof. The quadratic term implies a period decrease at a rate of \\dot{P}_orb = -7..-11 * 10^(-12) sec/sec. In case the observed period change reflects a true angular momentum loss, this would be a factor of 30 larger than given by gravitational radiation.
Drilled by the jet? XMM-Newton discovers a Compton-thick AGN in the GPS galaxy Mkn668
2004-01-01
We report the XMM-Newton discovery of the first Compton-thick obscured AGN in a Broad Line Radio Galaxy, the Gigahertz Peaked-Spectrum source Mkn668 (OQ+208). The remarkably flat 2-10 keV X-ray spectrum (observed photon index, \\Gamma ~ 0.7), alongside with a prominent iron K-alpha fluorescent emission line, is a clear signature of a Compton-reflection dominated spectrum. Mkn688 represents a remarkable example of discrepancy between X-ray spectral properties and optical classification, as its optical spectrum is characterized by broad and asymmetric Balmer lines. The obscuring matter is constrained to be located within the radio hotspots, in turn separated by about 10 pc. If the jets are piercing their way through a Compton-thick medium pervading the nuclear environment, one could be largely underestimating the radio activity dynamical age determined from the observed hotspot recession velocity. The soft X-ray spectrum is dominated by a much steeper component, which may be due to nuclear continuum electron scattering, or inverse Compton of the - remarkably large - far infrared emission. Soft X-rays are suppressed by a further Compton-thin (N_H ~ 10^21/cm/cm) absorbing system, that we identify with matter responsible for free-free absorption of the radio lobes.
XMM-Newton observations of X-ray emission from Jupiter
2005-12-09
We present the results of two XMM-Newton observations of Jupiter carried out in 2003 for 100 and 250 ks (or 3 and 7 planet rotations) respectively. X-ray images from the EPIC CCD cameras show prominent emission from the auroral regions in the 0.2 - 2.0 keV band: the spectra are well modelled by a combination of emission lines, including most prominently those of highly ionised oxygen (OVII and OVIII). In addition, and for the first time, XMM-Newton reveals the presence in both aurorae of a higher energy component (3 - 7 keV) which is well described by an electron bremsstrahlung spectrum. This component is found to be variable in flux and spectral shape during the Nov. 2003 observation, which corresponded to an extended period of intense solar activity. Emission from the equatorial regions of Jupiter's disk is also observed, with a spectrum consistent with that of solar X-rays scattered in the planet's upper atmosphere. Jupiter's X-rays are spectrally resolved with the RGS which clearly separates the prominent OVII contribution of the aurorae from the OVIII, FeXVII and MgXI lines, originating in the low-latitude disk regions of the planet.
Two dimensional silicon waveguide chirped grating couplers for vertical optical fibers
2010-01-01
Shallow etched two dimensional gratings for coupling light between silicon-on-insulator nanophotonic waveguides and vertical optical fibers were designed and experimentally characterized. We show that the large second order back reflection could be suppressed effectively by applying a linear chirp in the grating period for two dimensional grating couplers. The total coupling efficiency from an optical fiber to two orthogonal silicon waveguides is independent of the input polarization. An almost linear relationship between the average effective index of the grating region and the fill factor for 1D grating is obtained and verified. We also show that the average effective index for the two dimensional grating is similar to the one dimensional grating with the same fill factor in the light pr...
Two dimensional silicon waveguide chirped grating couplers for vertical optical fibers
Shallow etched two dimensional gratings for coupling light between silicon-on-insulator nanophotonic waveguides and vertical optical fibers were designed and experimentally characterized. We show that the large second order back reflection could be suppressed effectively by applying a linear chirp in the grating period for two dimensional grating couplers. The total coupling efficiency from an optical fiber to two orthogonal silicon waveguides is independent of the input polarization. An almost linear relationship between the average effective index of the grating region and the fill factor for 1D grating is obtained and verified. We also show that the average effective index for the two dimensional grating is similar to the one dimensional grating with the same fill factor in the light propagation direction, when the fill factor of the etched holes was larger than 0.5.
The Properties and the Evolution of the Highly Ionized Gas in MR2251-178
2004-01-01
(abridged) We present the first XMM-Newton observations of the radio-quiet quasar MR2251-178 obtained in 2000 and 2002. The EPIC-pn spectra show a power-law continuum with a slope of 1.6 at high energies absorbed by at least two warm absorbers (WAs) intrinsic to the source. The underlying continuum in the earlier observation shows a soft excess at low X-ray energies which can be modeled as an additional power-law with a slope of 2.9. The high-resolution grating spectrum obtained in 2002 shows emission lines from N VI, O VII, O VIII, Ne IX, and Ne X, as well as absorption lines from the low-ionization ions of O III, O IV, and O V, and other confirmed and suspected weaker absorption lines. We suggest a model for the high-resolution spectrum which consist of two or three WA components. The two-components model has a high-ionization WA with a column density of 10^21.5 - 10^21.8 cm^-2 and a low-ionization absorber with a column density of 10^20.3 cm^-2. In the three-components model we add a lower ionization component that produce the observed iron M-shell absorption lines. We investigate the spectral variations in MR2251-178 over a period of 8.5 years using data from ASCA, BeppoSAX, and XMM-Newton. All X-ray observations can be fitted with the above EPIC-pn model. The 8.5 year history of the source suggests a changing X-ray absorber due to material that enters and disappears from the line-of-sight on timescales of several months. We also present the entire FUSE spectrum of MR2251-178. We detect emission from N III, C III, and O VI and at least 4 absorption systems in C III, H I, and O VI, one at -580 km/s and at least 3 others which are blended together and form a wide trough covering the velocity range of 0 to -500 km/s. The general characteristics of the UV and X-ray absorbers are consistent with an origin in the same gas.
Band-edge-induced Bragg diffraction in two-dimensional photonic crystals.
Two-dimensional photonic crystals composed of two orthogonal volume diffraction gratings have been photogenerated in photopolymers. When the read beam is set at the Bragg angle, the diffraction efficiency of the transmission grating is strongly enhanced at the band edge of the reflection grating recorded in the material. Such a device provides Bragg operation and enhancement of the diffraction efficiency of the thin diffraction grating together with good wavelength selectivity. Such advantages could be interesting for optical signal processing.
XMM-Newton and INTEGRAL spectroscopy of GRO J1655-40 during its 2005 outburst
We report on two XMM-Newton and simultaneous INTEGRAL observations of the microquasar GRO J1655-40 during its 2005 outburst. The source was in its high-soft state during both observations. There is evidence for the presence of both a relativistically broadened Fe line providing strong support for the existence of a spinning black hole, and a highly photo-ionized absorber. The photo-ionized absorber is responsible for strong K absorption lines of Fe XXV and Fe XXVI in the EPIC pn spectra. The parameters of the highly-ionized absorber were different during the two observations. A less ionized absorber is present in the second observation, where the 0.5-200 keV luminosity of GRO J1655-40 decreased by around a half.
XMM-Newton and INTEGRAL spectroscopy of GRO J1655-40 during its 2005 outburst
2007-01-01
We report on two XMM-Newton and simultaneous INTEGRAL observations of the microquasar GRO J1655-40 during its 2005 outburst. The source was in its high-soft state during both observations. There is evidence for the presence of both a relativistically broadened Fe line providing strong support for the existence of a spinning black hole, and a highly photo-ionized absorber. The photo-ionized absorber is responsible for strong K absorption lines of Fe XXV and Fe XXVI in the EPIC pn spectra. The parameters of the highly-ionized absorber were different during the two observations. A less ionized absorber is present in the second observation, where the 0.5-200 keV luminosity of GRO J1655-40 decreased by around a half
XMM-Newton Observations of the Cataclysmic Variable GW Lib
2007-06-25
XMM-Newton observations of the accreting, pulsating white dwarf in the quiescent dwarf nova GW Librae were conducted to determine if the non-radial pulsations present in previous UV and optical data affect the X-ray emission. The non-radial pulsations are evident in the simultaneous Optical Monitor data but are not detected in X-ray with an upper limit on the pulsation amplitude of 0.092 mags. The best fits to the X-ray spectrum are with a low temperature diffuse gas model or a multi-temperature cooling flow model, with a strong OVIII line, similar to other short period dwarf novae, but with a lower temperature range than evident in normal short period dwarf novae. The lack of pulsations and the spectrum likely indicate that the boundary layer does not extend to the surface of the white dwarf.
Tracing a Z-track in the M31 X-ray Binary RX J0042.6+4115
2003-09-26
Four XMM-Newton observations of the core of M31, spaced at 6 month intervals, show that the brightest point X-ray source, RX J0042.6+4115, has a 0.4-10 keV luminosity of ~5 10^38 erg/s, and exhibits significant variability in intensity and X-ray spectrum over a time scale of ~100 s including hard flares; such behaviour is only observed in Z-sources and transient blackhole binaries in our Galaxy. The lightcurves, X-ray spectra and hardness-intensity data from the four XMM-Newton observations all strongly suggest that it is a Z-source, bringing the total number of known Z-sources to nine.
In-orbit performance of the EPIC-MOS detectors on XMM-Newton
2004-01-01
XMM-Newton was launched into space on a highly eccentric 48 hour orbit on December 10th 1999. XMM-Newton is now in its fifth year of operation and has been an outstanding success, observing the Cosmos with imaging, spectroscopy and timing capabilities in the X-ray and optical wavebands. The EPIC-MOS CCD X-ray detectors comprise two out of three of the focal plane instruments on XMM-Newton. In this paper we discuss key aspects of the current status and performance history of the charge transfer ineffiency (CTI), energy resolution and spectral redistribution function (rmf) of EPIC-MOS in its fifth year of operation.
2006-10-31
Using the recent XMM-Newton PN blank sky data, we improve the earlier restrictions on parameters of the warm dark matter (DM) in the form of sterile neutrino (by as much as the order of magnitude at masses ~ 3.5 kev). The results are obtained from non-observing DM decay line in the X-ray spectrum of the Milky Way. We also present similar constraint coming from the recent XMM-Newton observation of Ursa Minor -- dark, X-ray quiet dwarf spheroidal. Although this observation has relatively poor statistics, the constraints are comparable to those, recently obtained using observations of Large Magellanic Cloud or M31. This confirms recent proposal that dwarf satellites of the MW are very interesting candidates for the DM search and should be studied dedicatedly on this purpose.
Constraints on decaying Dark Matter from XMM-Newton observations of M31
2007-09-17
We derive constraints on parameters of the radiatively decaying Dark Matter (DM) particles, using XMM-Newton EPIC spectra of the Andromeda galaxy (M31). Using the observations of the outer (5'-13') parts of M31 we improve the existing constraints. For the case of sterile neutrino DM, combining our constraints with the latest computation of abundances of sterile neutrino in the Dodelson-Widrow (DW) scenario, we obtain the lower mass limit m_s 5.6 kev), we argue that the scenario in which all the DM is produced via DW mechanism is ruled out. We discuss however other production mechanisms and note that the sterile neutrino remains a viable candidate of Dark Matter, either warm or cold.
A Serendipitous XMM-Newton Observation of the Intermediate Polar WX Pyx
2004-12-16
We briefly describe a serendipitous observation of the little-studied intermediate polar WX Pyx using XMM-Newton. The X-ray spin period is 1557.3 sec, confirming the optical period published in 1996. An orbital period of approximately 5.54 hr is inferred from the separation of the spin-orbit sidelobe components. The soft and hard band spin-folded light curves are nearly sinusoidal in shape. The best-fit spectrum is consistent with a bremsstrahlung temperature of about 18 keV. An upper limit of approximately 300 eV is assigned to the presence of Fe line emission. WX Pyx lies near TX and TV Col in the P_spin-P_orb plane.
Laser-induced gratings in molecular oxygen excited via transitions in the red system
1996-06-01
Laser-induced gratings have been generated by exciting transitions in the red system of molecular oxygen. The temporal evolution of the grating reflectivity was studied at room temperature and atmospheric pressure. Contributions to the grating reflectivity arise from a change in population distribution caused by absorption, from electrostriction, and from a release of absorbed laser light in form of heat. Adding an efficient quencher like water to the oxygen sample strongly increases the grating reflectivity, rendering the laser-induced grating method sensitive enough to detect the isotopic molecule {sup 16}O{sup 18}O in its natural abundance. (author) 3 figs., 5 refs.
X-ray calibration of the Electro-Optical Breadboard Model (EOBB) of the XXM Reflection Grating Spectrometer has been carried out at the Panter test facility in Germany. The EOBB prototype optics consisted of a four-shell grazing incidence mirror module followed by an array of eight reflection gratings. The dispersed x-rays were detected by an array of three CCDs. Line profile and efficiency measurements where made at several energies, orders, and geometric configurations for individual gratings and for the grating array as a whole. The x-ray measurements verified that the grating mounting method would meet the stringent tolerances necessary for the flight instrument. Post EOBB metrology of the individual gratings and their mountings confirmed the precision of the grating boxes fabrication. Examination of the individual grating surface`s at micron resolution revealed the cause of anomalously wide line profiles to be scattering due to the crazing of the replica`s surface.
Gratings for High-Energy Petawatt Lasers
To enable high-energy petawatt laser operation we have developed the processing methods and tooling that produced both the world's largest multilayer dielectric reflection grating and the world's highest laser damage resistant gratings. We have successfully delivered the first ever 80 cm aperture multilayer dielectric grating to LLNL's Titan Intense Short Pulse Laser Facility. We report on the design, fabrication and characterization of multilayer dielectric diffraction gratings.
Gratings for High-Energy Petawatt Lasers
2005-11-08
To enable high-energy petawatt laser operation we have developed the processing methods and tooling that produced both the world's largest multilayer dielectric reflection grating and the world's highest laser damage resistant gratings. We have successfully delivered the first ever 80 cm aperture multilayer dielectric grating to LLNL's Titan Intense Short Pulse Laser Facility. We report on the design, fabrication and characterization of multilayer dielectric diffraction gratings.
Design and performance of a complex-coupled DFB laser with sampled grating
2009-01-01
A complex-coupled DFB laser with sampled grating has been designed and fabricated. The method uses the +1st order reflection of the sampled grating for laser single-mode operation. The typical threshold current of the sampled grating based DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5385 mum, which is the +1st order wavelength of the sampled grating
2004-08-23
We report on a short XMM-Newton observation of the radio-quiet Narrow Line Seyfert 1 PG 1402+261. The EPIC X-ray spectrum of PG 1402+261 shows a strong excess of counts between 6-9 keV in the rest frame. This feature can be modeled by an unusually strong (equivalent width 2 keV) and very broad (FWHM velocity of 110000 km/s) iron K-shell emission line. The line centroid energy at 7.3 keV appears blue-shifted with respect to the iron Kalpha emission band between 6.4-6.97 keV, while the blue-wing of the line extends to 9 keV in the quasar rest frame. The line profile can be fitted by reflection from the inner accretion disk, but an inclination angle of >60 deg is required to model the extreme blue-wing of the line. Furthermore the extreme strength of the line requires a geometry whereby the hard X-ray emission from PG 1402+261 above 2 keV is dominated by the pure-reflection component from the disk, while little or none of the direct hard power-law is observed. Alternatively the spectrum above 2 keV may instead be explained by an ionized absorber, if the column density is sufficiently high (N_H > 3 x 10^23 cm^-2) and if the matter is ionized enough to produce a deep (tau~1) iron K-shell absorption edge at 9 keV. This absorber could originate in a large column density, high velocity outflow, perhaps similar to those which appear to be observed in several other high accretion rate AGN. Further observations, especially at higher spectral resolution, are required to distinguish between the accretion disk reflection or outflow scenarios.
In a typical optic fiber Bragg grating (FBG) strain measurement, unless in an ideal static laboratory environment, the presence of vibration or often disturbance always exists, which often creates spurious ...
2008-11-20
The increase of cell efficiency resulting from using a diffraction grating as a back reflector is investigated. An enhancement coefficient is introduced as a figure of merit that accounts for the ability of the rear grating to increase the generation of electric carriers. According to results in this paper, a diffraction-grating-like relief on the rear face of the photovoltaic cell may reduce the intensity of the specular reflection while favouring the intensity of high-angle rays. In this way, the path-length of reflected rays increases, and so does the efficiency of the cell.
XMMOMSUSS - XMM-Newton Optical Monitor Serendipitous UV Source ...
... matching criteria for another image, the nearest source is adopted as the match. ... Significance is calculated on raw count rates, uncorrected for photon ... quantities of photon coincidence loss where two photons arriving at the same ..... object 2 Source lies potentially over a ghost ring originating from a ...
2008-05-28
We report on two XMM-Newton observations performed in 2006 of the luminous low-mass X-ray binary XB1832-330 which is located in the galactic globular cluster NGC 6652 and is probably an ultracompact binary (orbital period less than 1 hour). The aim of these observations is to investigate the low-energy absorption towards NGC6652 and in particular to search for Ne-rich material local to the binary, which has been suggested as a possible spectral signature of Neon rich degenerate companions. XMM-Newton observed the source twice, in 2006 September and October. High resolution spectroscopy with the RGS was used to estimate the ratio of the neutral neon to oxygen column densities to search for an anomalous Ne abundance in this X-ray binary. We find no evidence for anomalous Ne/O ratios, finding Ne/O=0.18+/-0.06 and Ne/O=0.17+/-0.03 (1 sigma uncertainties), in the two observations, respectively. These values are consistent with that in the interstellar medium. Timing analysis of EPIC data suggests possible periodicities at 9170+/-235 s and 18616 +/- 531 s, which need confirmation. A by-product of these observations consists of the spatial analysis of the source field, which resulted in the detection of 46 faint sources within the EPIC field of view, which are not present in the Second XMM-Newton Serendipitous Source Catalogue. All these faint sources are likely foreground objects. We performed the first high spectral resolution obser vations of XB1832-33, a probable ultracompact binary, without finding any evidence for an anomalous Ne abundance.
XMM-Newton calibration - an overview
2002-03-18
This paper introduces the articles that describe detailed aspects of the XMM-Newton calibration. The unique calibration issues of XMM-Newton are highlighted. The original calibration requirements and aspects of the ground calibration are summarized. The life cycle of the in-orbit calibration observations, analysis and ingestion into calibration files is discussed.
2010-07-16
Since the last phase coherent timing solution of the nearby radio-quiet isolated neutron star RX J0720.4-3125 six new XMM-Newton and three Chandra observations were carried out. The phase coherent timing solutions from previous authors were performed without restricting to a fixed energy band. However, we recently showed that the phase residuals are energy dependent, and thus phase coherent solutions must be computed referring always to the same energy band. We updated the phase coherent timing solution for RX J0720.4-3125 by including the recent XMM-Newton EPIC-pn, MOS1, MOS2 and Chandra ACIS data in the energy range 400-1000~eV. Altogether these observations cover a time span of almost 10~yrs. A further timing solution was obtained including the ROSAT pointed data. In this case, observations cover a time span of $\\approx$16~yrs. To illustrate the timing differences between the soft band (120-400~eV) and the hard band (400-1000~eV) a timing solution for the soft band is also presented and the results are verified using a $\\mathrm{Z_{n}^{2}}$ test. In contrast to previous work, we obtain almost identical solutions whether or not we include the ROSAT or Chandra data. Thanks to the restriction to the hard band, the data points from EPIC-pn are in better agreement with those from MOS1, MOS2 and Chandra than in previous works. In general the phase residuals are still large and vary with time. In particular, the latest XMM-Newton an d Chandra data show that the phase residuals have attained relatively large and negative values.
Supernova remnants, planetary nebulae and superbubbles: prospects for new XMM-Newton observations
2008-02-05
Important results achieved over the last years on supernova remnants, planetary nebulae and superbubbles are briefly reviewed in the context of X-ray observations. I intend to review the important open scientific questions in these fields, and the specific contributions that can be made by XMM-Newton.
2008-10-30
In the past, the isolated, radio-quiet neutron star RX J0720.4-3125 showed variations in the spectral parameters (apparent radius, temperature of the emitting area and equivalent width of the absorption feature) seen in the X-ray spectra, not only during the spin period of 8.39s, but also over time scales of years. New X-ray observations of RX J0720.4-3125 with XMM Newton extend the coverage to about 7.5 years with the latest pointing performed in November 2007. Out of a total of fourteen available EPIC-pn datasets, eleven have been obtained with an identical instrumental setup (full frame read-out mode with thin filter), and are best suited for a comparative investigations of the spectral and timing properties of this enigmatic X-ray pulsar. We analysed the new XMM Newton observations together with archival data in order to follow the spectral and temporal evolution of RX J0720.4-3125 All XMM-Newton data were reduced with the standard XMM-SAS software package. A systematic and consistent data reduction of all these observations was emphasised in order to reduce systematic errors as far as possible. We investigate the phase residuals derived from data from different energy bands using different timing solutions for the spin period evolution and confirm the phase lag between hard and soft photons. The phase shift in the X-ray pulses between hard and soft photons varies with time and changes sign around MJD=52800 days, regardless of the chosen timing solution. The phase residuals[abridge]
A long XMM-Newton exposure is used to observe solar wind charge exchange (SWCX) emission from exospheric material in and outside Earth's magnetosheath. The light curve of the O vii (0.5-0.62 keV) band is compared with ...
Constraining the neutron star equation of state using XMM-Newton
2007-11-19
We have identified three possible ways in which future XMM-Newton observations can provide significant constraints on the equation of state of neutron stars. First, using a long observation of the neutron star X-ray transient CenX-4 in quiescence one can use the RGS spectrum to constrain the interstellar extinction to the source. This removes this parameter from the X-ray spectral fitting of the pn and MOS spectra and allows us to investigate whether the variability observed in the quiescent X-ray spectrum of this source is due to variations in the soft thermal spectral component or variations in the power law spectral component coupled with variations in N_H. This will test whether the soft thermal spectral component can indeed be due to the hot thermal glow of the neutron star. Potentially such an observation could also reveal redshifted spectral lines from the neutron star surface. Second, XMM-Newton observations of radius expansion type I X-ray bursts might reveal redshifted absorption lines from the surface of the neutron star. Third, XMM-Newton observations of eclipsing quiescent low-mass X-ray binaries provide the eclipse duration. With this the system inclination can be determined accurately. The inclination determined from the X-ray eclipse duration in quiescence, the rotational velocity of the companion star and the semi-amplitude of the radial velocity curve determined through optical spectroscopy, yield the neutron star mass.
In the latest in our series of papers on XMM-Newton and ground-based optical follow-up of new candidate magnetic cataclysmic variables (mCVs) found in the Sloan Digital Sky Survey, we report classifications of ...
In the latest in our series of papers on XMM-Newton and ground-based optical follow-up of new candidate magnetic cataclysmic variables (mCVs) found in the Sloan Digital Sky Survey, we report classifications of three systems: ...
Arakelian 564: An XMM-Newton View
We report on two XMM-Newton observations of the bright narrow-line Seyfert 1 galaxy Ark 564 taken one year apart (2000 June and 2001 June). The 0.6-10 keV continuum is well described by a soft blackbody component ...
An Extreme, Blueshifted Iron Line in the Narrow Line Seyfert 1 PG 1402261
We report on a short, XMM-Newton observation of the radio-quiet Narrow Line Seyfert 1 PG 1402261. The EPIC X-ray spectrum of PG 1402261 shows a strong excess of counts between 6 - 9 keV in the rest frame. This feature ...
The X-ray spectrum of the newly discovered accreting millisecond pulsar IGR J17511-3057
2010-05-27
We report on an XMM-Newton observation of the accreting millisecond pulsar, IGR J17511-3057. Pulsations at 244.8339512(1) Hz are observed with an RMS pulsed fraction of 14.4(3)%. A precise solution for the P_orb=12487.51(2)s binary system is derived. The measured mass function indicates a main sequence companion with a mass between 0.15 and 0.44 Msun. The XMM-Newton spectrum of the source can be modelled by at least three components, multicoloured disc emission, thermal emission from the NS surface and thermal Comptonization emission. Spectral fit of the XMM-Newton data and of the RXTE data, taken in a simultaneous temporal window, constrain the Comptonization parameters: the electron temperature, kT_e=51(+6,-4) keV, is rather high, while the optical depth (tau=1.34(+0.03,-0.06)) is moderate. The energy dependence of the pulsed fraction supports the interpretation of the cooler thermal component as coming from the accretion disc, and indicates that the Comptonizing plasma surrounds the hot spots on the NS surface, which provide the seed photons. Signatures of reflection, such as a broadened iron K-alpha emission line and a Compton hump at 30 keV ca., are also detected. We derive from the smearing of the reflection component an inner disc radius of ~> 40 km for a 1.4 Msun neutron star, and an inclination between 38{\\deg} and 68{\\deg}. XMM-Newton also observed two type-I X-ray bursts, probably ignited in a nearly pure helium envi ronment. No photospheric radius expansion is observed, thus leading to an upper limit on the distance to the source of 10 kpc. A lower limit of 6.5 kpc can be also set if it is assumed that emission during the decaying part of the burst involves the whole neutron star surface. Pulsations observed during the burst decay are compatible with being phase locked, and have a similar amplitude, than pre-burst pulsations.
System and technique for characterizing fluids using ultrasonic diffraction grating spectroscopy
A system for determining property of multiphase fluids based on ultrasonic diffraction grating spectroscopy includes a diffraction grating on a solid in contact with the fluid. An interrogation device delivers ultrasound through the solid and a captures a reflection spectrum from the diffraction grating. The reflection spectrum exhibits peaks whose relative size depends on the properties of the various phases of the multiphase fluid. For example, for particles in a liquid, the peaks exhibit dependence on the particle size and the particle volume fraction. Where the exact relationship is know know a priori, data from different peaks of the same reflection spectrum or data from the peaks of different spectra obtained from different diffraction gratings can be used to resolve the size and volume fraction.
Design and analysis of the reflection grating arrays for the X-Ray Multi-Mirror Mission (XMM)
1990-06-01
The Reflection Grating Spectrometer Experiment (RGS), which has been selected for flight on the European Space Agency's X-ray Multi-Mirror Mission (XMM), includes two arrays of reflection gratings that are placed in the X-ray optical path behind two separate grazing incidence X-ray telescopes. Each of the gratings arrays picks off roughly half the X-ray light emanating from its telescope and diffracts it to a dedicated strip of charge-coupled device (CCD) detectors offset from the telescope focal plane. The arrays contain 224 100 mm X 200 mm gratings, each mounted at a graze angle of 1.58{degree} to the incident beam. The gratings are produced by epoxy replication of a common master onto very thin substrates. Both the gratings and the detector are mounted on a Rowland circle which also includes the telescope focus. In this paper, we review the current state of both the engineering and the optical designs for the grating arrays. 4 refs., 9 figs.
XMM-Newton view of the prototype narrow-line Seyfert 1 galaxy I Zw 1
2003-12-12
We present results based on an XMM-Newton observation of the prototype narrow-line Seyfert 1 galaxy I Zw 1 performed in June 2002. The 0.6-12 keV spectrum is well described by a steep power-law (Gamma\\sim 2.3) and a weak soft blackbody component (kT \\sim 200 eV) below 2 kev. The soft X-ray excess emission is featureless and contributes only about 10% to the total X-ray emission in the $0.6-2\\kev$ band. There are tentative evidences for an iron iron Kalpha line and an iron K edge, both from high ionized He-like iron. The 0.6-12kev continuum of I Zw 1 can be explained in terms of a blackbody (kT \\sim 40eV), thermal comptonization and its reflection off the surface of an ionized accretion disk. We note that characterizing the soft excess copmonent `above a power law continuum' may not be appropriate due to the low energy curvature of a comptonized spectrum. X-ray emission from I Zw 1 was highly variabile during the observation. I Zw 1 showed a large, symmetric X-ray flare during which the X-ray luminosity increased by about 6e43 erg/s in an interval of 2800s only. The X-ray spectral variability was unusual during the flare. In contrast to the general observation of spectral steepening with flux from Seyfert galaxies, there is a clear evidence for hardening of the 0.6-10kev spectrum of I Zw 1 with increasing flux. This hardening is due to a stronger and slightly flatter power-law component at higher flux without any change in the soft X-ray excess component. The large flare, the accompanying spectral flattening, and the steady nature of the soft excess component may be due to an additional flatter power-law component during the flare possibly arising as a result of ejection of electron plasma and the SSC process.
The Suzaku Hard X-ray Survey on the Galactic Center Region
2010-07-29
Diffuse X-rays from the Galactic center (GC) region were found to exhibit many K-shell lines from iron and nickel atoms in the 6--9 keV band. The strong emission lines seen in the spectrum are neutral iron K$\\alpha$ at 6.4~keV, He-like iron K$\\alpha$ at 6.7~keV, H-like iron Ly$\\alpha$ at 6.9~keV, and He-like iron K$\\beta$ at 7.8~keV. Among them, the 6.4~keV emission line is a probe of non-thermal phenomena. We have detected strong 6.4~keV emission in several giant molecular clouds, some of which were newly discovered by Suzaku. All the spectra exhibit large equivalent widths of 1-2~keV and absorption columns of $2-10\\times 10^{23}\\{\\rm H\\ cm}^{-2}$. We found time variability of diffuse 6.4~keV emission in the Sgr B2 region comparing the maps and spectra obtained from 1994 to 2005 with ASCA, Chandra, XMM-Newton and Suzaku. We also report discovery of K$\\alpha$ lines of neutral argon, calcium, chrome, and manganese atoms in the Sgr~A region. We show that the equivalent width of the 6.4~keV emission line detected in X-ray faint region against the 6.4 keV-associated continuum (power-law component) is $\\sim 800\\ {\\rm eV}$. These features are naturally explained by the X-ray reflection nebula scenario rather than the low energy cosmic-ray electrons scenario. On the other hand, a 6.4~keV clump, G~0.162$-$0.217, discovered at the south end of the Radio Arc has a small equivalent width of 6.4~keV emission line of $\\sim200\\ {\\rm eV}$. Th e Radio Arc is a site of relativistic electrons. Thus, it is conceivable that the X-rays of G~0.162$-$0.217 are due to low energy cosmic-ray electrons
Orbital and Spin Phase-Resolved Spectroscopy of the Intermediate Polar EX Hya Using XMM-Newton Data
2010-09-23
We present for the first time orbital phase-resolved spectra of an intermediate polar (IP), EX Hya, together with the spin phase-resolved spectra during two different epochs using the X-ray Multi-Mirror Mission, European Photon Imaging Camera (pn instrument). We find that the source at the two epochs has the same X-ray luminosity of $\\sim$ 6.5 $\\times$ 10$^{31}$ erg s$^{-1}$. We detect spectral variations between the 2000 and 2003 observations of the source. We fitted the spectrum using a neutral hydrogen absorption model with or without covering fraction together with Gaussians for emission lines, two collisional equilibrium plasma emission models (MEKAL) and a cooling-flow plasma emission model (VMCFLOW). We find that two of the three emission components ($kT$=0.6-0.8 keV and $kT$=1.3-1.7 keV) fitted by the MEKAL models are almost constant over the spin and orbital phases and also over the two different epochs with the normalisation varying directly proportional to the flux when the data are folded according to the orbital and spin phase indicating that the slight variation may be due to occultation. The emission modeled by the VMCFLOW changes over the spin and orbital phases and the 2000 and 2003 observations reveal two different ranges of temperatures (3-33 and 8-61 keV respectively) that model the shock zone in the accretion column/s. The ratios of the spin maximum to minimum and the orbital maximum to minimum spectra alon g with the increase in the plasma temperatures indicate that the spectrum gets harder in the minimum phases of both orbital and spin periods. In the 2003 observation, a 6.4 keV fluorescent Fe emission line is present at the orbital minima in a range of phases from 0.9 to 1.3 and it is absent otherwise. This indicates that there is reflection from the disc most likely from a large bulge at the accretion impact zone.
2010-03-11
We present the result of a study of the X-ray emission from the Galactic Centre (GC) Molecular Clouds (MC) within 15 arcmin from Sgr A*. We use XMM-Newton data (about 1.2 Ms of observation time) spanning about 8 years. The MC spectra show all the features characteristic of reflection: i) intense Fe Kalpha, with EW of about 0.7-1 keV, and the associated Kbeta line; ii) flat power law continuum and iii) a significant Fe K edge (tau~0.1-0.3). The diffuse low ionisation Fe K emission follows the MC distribution, nevertheless not all MC are Fe K emitters. The long baseline monitoring allows the characterisation of the temporal evolution of the MC emission. A complex pattern of variations is shown by the different MC, with some having constant Fe K emission, some increasing and some decreasing. In particular, we observe an apparent super-luminal motion of a light front illuminating a Molecular nebula. This might be due to a source outside the MC (such as Sgr A* or a bright and long outburst of a X-ray binary), while it cannot be due to low energy cosmic rays or a source located inside the cloud. We also observe a decrease of the X-ray emission from G0.11-0.11, behaviour similar to the one of Sgr B2. The line intensities, clouds dimensions, columns densities and positions with respect to Sgr A*, are consistent with being produced by the same Sgr A* flare. The required high luminosity (about 1.5~10^39 erg/s) can hardly be produced by a binary system, while it is in agreement with a flare of Sgr A* fading about 100 years ago. The low intensity of the Fe K emission coming from the 50 and the 20 km/s MC places an upper limit of 10^36 erg/s to the mean luminosity of Sgr A* in the last 60-90 years. The Fe K emission and variations from these MC might have been produced by a single flare of Sgr A*.
Grating light reflection spectroscopy (GLRS) is an emerging technique for spectroscopic analysis and sensing. A transmission diffraction grating is placed in contact with the sample to be analyzed, and an incident light beam is directed onto the grating. At certain angles of incidence, some of the diffracted orders are transformed from traveling waves to evanescent waves. This occurs at a specific wavelength that is a function of the grating period and the complex index of refraction of the sample. The intensities of diffracted orders are also dependent on the sample's complex index of refraction. The authors describe the use of GLRS, in combination with electrochemical modulation of the grating, for the detection of trace amounts of aromatic hydrocarbons. The diffraction grating consisted of chromium lines on a fused silica substrate. The depth of the grating lines was 1 {micro}m, the grating period was 1 {micro}m, and the duty cycle was 50%. Since chromium was not suitable for electrochemical modulation of the analyte concentration, a 200 nm gold layer was deposited over the entire grating. This gold layer slightly degraded the transmission of the grating, but provided satisfactory optical transparency for the spectroelectrochemical experiments. The grating was configured as the working electrode in an electrochemical cell containing water plus trace amounts of the aromatic hydrocarbon analytes. The grating was then electrochemically modulated via cyclic voltammetry waveforms, and the normalized intensity of the zero order reflection was simultaneously measured. The authors discuss the lower limits of detection (LLD) for two analytes, 7-dimethylamino-1,2-benzophenoxazine (Meldola's Blue dye) and 2,4,6-trinitrotoluene (TNT), probed with an incident HeNe laser beam ({lambda} = 543.5 nm) at an incident angle of 52.5{degree}. The LLD for 7-dimethylamino-1,2-benzophenoxazine is approximately 50 parts per billion (ppb), while the LLD for TNT is approximately 50 parts per million (ppm). The possible factors contributing to the differences in LLD for these analytes are discussed. This is the final report for a Sandia National Laboratories Laboratory Directed Research and Development (LDRD) project conducted during fiscal years 1998 and 1999 (case number 3518.190).
2000-04-01
Grating light reflection spectroscopy (GLRS) is an emerging technique for spectroscopic analysis and sensing. A transmission diffraction grating is placed in contact with the sample to be analyzed, and an incident light beam is directed onto the grating. At certain angles of incidence, some of the diffracted orders are transformed from traveling waves to evanescent waves. This occurs at a specific wavelength that is a function of the grating period and the complex index of refraction of the sample. The intensities of diffracted orders are also dependent on the sample's complex index of refraction. The authors describe the use of GLRS, in combination with electrochemical modulation of the grating, for the detection of trace amounts of aromatic hydrocarbons. The diffraction grating consisted of chromium lines on a fused silica substrate. The depth of the grating lines was 1 {micro}m, the grating period was 1 {micro}m, and the duty cycle was 50%. Since chromium was not suitable for electrochemical modulation of the analyte concentration, a 200 nm gold layer was deposited over the entire grating. This gold layer slightly degraded the transmission of the grating, but provided satisfactory optical transparency for the spectroelectrochemical experiments. The grating was configured as the working electrode in an electrochemical cell containing water plus trace amounts of the aromatic hydrocarbon analytes. The grating was then electrochemically modulated via cyclic voltammetry waveforms, and the normalized intensity of the zero order reflection was simultaneously measured. The authors discuss the lower limits of detection (LLD) for two analytes, 7-dimethylamino-1,2-benzophenoxazine (Meldola's Blue dye) and 2,4,6-trinitrotoluene (TNT), probed with an incident HeNe laser beam ({lambda} = 543.5 nm) at an incident angle of 52.5{degree}. The LLD for 7-dimethylamino-1,2-benzophenoxazine is approximately 50 parts per billion (ppb), while the LLD for TNT is approximately 50 parts per million (ppm). The possible factors contributing to the differences in LLD for these analytes are discussed. This is the final report for a Sandia National Laboratories Laboratory Directed Research and Development (LDRD) project conducted during fiscal years 1998 and 1999 (case number 3518.190).
The particle size of a slurry and the viscosity of a liquid or slurry are both difficult to measure on-line and in real time. The objectives of this research are to develop the following methods for such measurements: (1) ultrasonic diffraction grating spectroscopy (UDGS) to measure the particle size of a slurry, (2) UDGS to measure the velocity of sound in a slurry using reflection from a grating as opposed to ultrasound traveling through a possibly dense slurry, and (3) shear wave reflection techniques to measure the viscosity of a slurry.
Observing Effects of Particle Size for a Slurry Using Ultrasonic Diffraction Grating Spectroscopy
2005-05-01
The ultrasonic diffraction grating is formed by machining triangular grooves, 240 microns apart, on the flat surface of a stainless steel (SS) half-cylinder. ultrasound from a send transducer travels through the SS and strikes the back of the grating where it is reflected to a receive transducer. A peak in the receive signal is used to determine the velocity of sound and observe effects of particle size.
Large Aperture, High-Efficiency Multilayer Dielectric Reflection Gratings
2002-04-12
The authors have designed and fabricated a 355 x 150 mm multilayer dielectric diffraction grating, 1800 l/mm for 1030 nm light, that exhibits >99% diffraction efficiency and a diffracted wavefront flatness of <0.15 {lambda}. This grating is an enabling component of a 1 ps, high rep-rate machining laser currently in operation at LLNL.
2006-06-01
The particle size of a slurry and the viscosity of a liquid or slurry are both difficult to measure on-line and in real time. The objectives of this research are to develop the following methods for such measurements: (1) ultrasonic diffraction grating spectroscopy (UDGS) to measure the particle size and concentration of a slurry, (2) develop theoretical models and computer codes to describe the passage of ultrasound through a grating surface in order to increase the sensitivity of the particle size measurement.
Nonspecular reflection of waves by waveguide-type gratings. General principles
1986-01-01
The general principles of nonspecular reflection of plane waves from gratings containing regions with well-expressed waveguide properties are studied. Excitation regimes which permit concentration of all or a large portion of the energy in one of the higher spatial harmonics are classified and analyzed for both the autocollimation regime and for differing angles of wave incidence and reflection
Design and properties analysis of total internal reflection gratings for pulse compressor at 1053 nm
2011-01-01
High-efficiency compression gratings based on total internal reflection (TIR) are promising alternatives of compressor gratings because of their high diffraction efficiency, potential high damage resistant ability, and compact structure. Dependence of the -1 order diffraction efficiencies on grating parameters is analyzed for TE- and TM-polarized incident light of 1053 nm at Littrow angle, which is calculated by using the rigorous coupled-wave analysis. A more intuitional view on the relation is offered through three-dimensional slicing figures instead of two-dimensional ones. The performances of high-efficiency gratings are compared and regarded as criteria for further choices, including spectral bandwidth, angle bandwidth, dispersion, and intensity distribution. For TE- and TM-irradiatio...
The theory of attenuated total reflection by surface polaritons on one-sided corrugated thin films
2003-01-01
The experimental techniques of attenuated total reflection (ATR) and grating coupling were originally employed separately as probes for polaritons. The combined technique of these methods into a single probe is a very versatile tool for probing elementary surface excitations. A theoretical investigation of this single probe for surface polaritons, ATR-grating coupling, is undertaken. The emphasis is on the calculations of first-order diffuse reflectivities, which arise due to the presence of a classical grating. More specifically, the ATR set-up in the Otto configuration is considered and for ease of presentation of the results, a classical grating is thought to be deposited on only one interface of a surface-active thin-film specimen. The discussion highlights the advantages the combined technique has over either of the two methods when each is employed on its own.
We report observations and measurements of the inscription of fiber Bragg gratings (FBGs) in two different types of microstructured polymer optical fiber: few-mode and an endlessly single mode. Contrary to the FBG inscription in silica microstructured fiber, where high-energy laser pulses are a prerequisite, we have successfully used a low-power cw laser source operating at 325 nm to produce 1 cm long gratings with a reflection peak at 1570 nm. Peak reflectivities of more than 10% have been observed.
1990-06-01
An approach and development plan for the production of replicated variable line spacing x-ray reflection gratings on lightweight substrates is described. The gratings will be arrayed in spectrometers to analyze the soft x-rays gathered by the telescopes flown around the European Space Agency (ESA) X-ray Multi-Mirror Mission'' (XMM). The mission requires about 750 gratings to form 3 arrays. Each array provides a grating area of approximately 5 square meters. From relatively few master gratings, the low blaze angle gratings will be replicated onto 55 gram substrates having an equivalent length/thickness aspect ratio {ge}40. We will describe the criteria used for selecting the substrate design and material. A multi-phased study to solve identified technical problems associated with the replication of these gratings is also described. We will report on the present status of the substrates and replication process. 3 refs., 5 figs.
2010-01-01
When high-power laser beams pass through a volume Bragg grating (VBG), the surface of VBG occurs distortion because of thermal effects, and it results in the decline of the grating's performance. Considering distortion of the surface induces differences of the index and period, the scalar wave equations for super-Gaussian (SG) laser beams propagating in the reflection VBG have been solved by using finite-different and sparse matrix methods. The changes of the total power reflection coefficient, the beam width, the far-field beam angle and the M2-factor for the laser beams through the reflection VBG with deformation have been analyzed quantitatively. It can be shown that the deformation of the VBG affects evidently on the intensity and phase distributions, the total power reflection coeffic...
2007-01-07
We present X-ray observations of the as of yet unidentified very high-energy (VHE) gamma-ray source HESSJ1640-465 with the aim of establishing a counterpart of this source in the keV energy range, and identifying the mechanism responsible for the VHE emission. The 21.8 ksec XMM-Newton observation of HESSJ1640-465 in September 2005 represents a significant improvement in sensitivity and angular resolution over previous ASCA studies in this region. These new data show a hard-spectrum X-ray emitting object at the centroid of the H.E.S.S. source, within the shell of the radio Supernova Remnant (SNR) G338.3-0.0. This object is consistent with the position and flux previously measured by both ASCA and Swift-XRT but is now shown to be significantly extended. We argue that this object is very likely the counterpart to HESSJ1640-465 and that both objects may represent the Pulsar Wind Nebula of an as of yet undiscovered pulsar associated with G338.3-0.0.
We present X-ray observations of the as of yet unidentified very high-energy (VHE) {gamma}-ray source HESS J1640-465 with the aim of establishing a counterpart of this source in the keV energy range, and identifying the mechanism responsible for the VHE emission. The 21.8 ksec XMM-Newton observation of HESS J1640-465 in September 2005 represents a significant improvement in sensitivity and angular resolution over previous ASCA studies in this region. These new data show a hard-spectrum X-ray emitting object at the centroid of the H.E.S.S. source, within the shell of the radio Supernova Remnant (SNR) G338.3-0.0. This object is consistent with the position and flux previously measured by both ASCA and Swift-XRT but is now shown to be significantly extended. We argue that this object is very likely the counterpart to HESS J1640-465 and that both objects may represent the Pulsar Wind Nebula of an as of yet undiscovered pulsar associated with G338.3-0.0.
We present X-ray observations of the as of yet unidentified very high-energy (VHE) {gamma}-ray source HESS J1640-465 with the aim of establishing a counterpart of this source in the keV energy range, and identifying the mechanism responsible for the VHE emission. The 21.8 ksec XMM-Newton observation of HESS J1640-465 in September 2005 represents a significant improvement in sensitivity and angular resolution over previous ASCA studies in this region. These new data show a hard-spectrum X-ray emitting object at the centroid of the H.E.S.S. source, within the shell of the radio Supernova Remnant (SNR) G338.3-0.0. This object is consistent with the position and flux previously measured by both ASCA and Swift-XRT but is now shown to be significantly extended. We argue that this object is very likely the counterpart to HESS J1640-465 and that both objects may represent the Pulsar Wind Nebula of an as of yet undiscovered pulsar associated with G338.3-0.0.
2007-03-05
We present X-ray observations of the as of yet unidentified very high-energy (VHE) {gamma}-ray source HESS J1640-465 with the aim of establishing a counterpart of this source in the keV energy range, and identifying the mechanism responsible for the VHE emission. The 21.8 ksec XMM-Newton observation of HESS J1640-465 in September 2005 represents a significant improvement in sensitivity and angular resolution over previous ASCA studies in this region. These new data show a hard-spectrum X-ray emitting object at the centroid of the H.E.S.S. source, within the shell of the radio Supernova Remnant (SNR) G338.3-0.0. This object is consistent with the position and flux previously measured by both ASCA and Swift-XRT but is now shown to be significantly extended. We argue that this object is very likely the counterpart to HESS J1640-465 and that both objects may represent the Pulsar Wind Nebula of an as of yet undiscovered pulsar associated with G338.3-0.0.
The outflow in Mrk 509: A method to calibrate XMM-Newton EPIC-pn and RGS
2010-02-23
We have analyzed three XMM-Newton observations of the Seyfert 1 galaxy Mrk 509, with the goal to detect small variations in the ionized outflow properties. Such measurements are limited by the quality of the cross-calibration between RGS, the best instrument to characterize the spectrum, and EPIC-pn, the best instrument to characterize the variability. For all three observations we are able to improve the relative calibration of RGS and pn consistently to 4 %. In all observations we detect three different outflow components and, thanks to our accurate cross-calibration we are able to detect small differences in the ionization parameter and column density in the highest ionized component of the outflow. This constrains the location of this component of the outflow to within 0.5 pc of the central source. Our method for modeling the relative effective area is not restricted to just this source and can in principle be extended to other types of sources as well.
The XMM-SSC survey of hard-spectrum XMM-Newton sources - I. Optically bright sources
2007-01-01
ABSTRACT We present optical and X-ray data for a sample of serendipitous XMM-Newton sources that are selected to have 0.5-2 versus 2-4.5 keV X-ray hardness ratios which are harder than the X-ray background. The sources have 2-4.5 keV X-ray flux Formula Not Shown , and in this paper we examine a subsample of 42 optically bright Formula Not Shown sources; this subsample is 100 per cent spectroscopically identified. All but one of the optical counterparts are extragalactic, and we argue that the single exception, a Galactic M star, is probably a coincidental association rather than the correct identification of the X-ray source. The X-ray spectra of all the sources are consistent with heavily absorbed power laws Formula Not Shown , and all of them, including the two sources with 2-10 keV intr...
Spatially resolved XMM-Newton analysis and a model of the nonthermal emission of MSH 15-52
2010-05-06
We present an X-ray analysis and a model of the nonthermal emission of the pulsar wind nebula (PWN) MSH15-52. We analyzed XMM-Newton data to obtain the spatially resolved spectral parameters around the pulsar PSRB1509-58. A steepening of the fitted power-law spectra and decrease in the surface brightness is observed with increasing distance from the pulsar. In the second part of this paper, we introduce a model for the nonthermal emission, based on assuming the ideal magnetohydrodynamic limit. This model is used to constrain the parameters of the termination shock and the bulk velocity of the leptons in the PWN. Our model is able to reproduce the spatial variation of the X-ray spectra. The parameter ranges that we found agree well with the parameter estimates found by other authors with different approaches. In the last part of this paper, we calculate the inverse Compton emission from our model and compare it to the emission detected with the H.E.S.S. telescope system. Our model is able to reproduce the flux level observed with H.E.S.S., but not the spectral shape of the observed TeV {\\gamma}-ray emission.
2009-01-01
We present simultaneous XMM-Newton and International Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the luminous black hole transient and relativistic jet source GX 339-4. GX 339-4 started an outburst on 2006 November and our observations were undertaken from 2007 January to March. We triggered five INTEGRAL and three XMM-Newton Target of Opportunity observations within this period. Our data cover different spectral states, namely hard intermediate, soft intermediate, and high/soft. We performed spectral analysis to the data with both phenomenological and more physical models and found that a nonthermal component seems to be required by the data in all the observations. We find a hardening of the spectrum in the third observation coincident with appearance of a broad and skewed Fe Kalpha line. In all spectral states joint ...
First XMM-Newton observations of a Cataclysmic Variable I$$bTiming studies of OY Car
We present XMM-Newton observations of the eclipsing, disc accreting, cataclysmic variable OY Car which were obtained as part of the performance verification phase of the mission. The star was observed 4 days after an outburst and then again 5 weeks later when it was in a quiescent state. There is a quasi-stable modulation of the X-rays at ~2240 sec, which is most prominent at the lowest energies. We speculate that this may be related to the spin period of the white dwarf. The duration of the eclipse ingress and egress in X-rays is 20--30 sec. This indicates that the bulk of the X-ray emission originates from the boundary layer which has a negligible height above the surface of the white dwarf. The eclipse profile implies a white dwarf of mass M_{1}=0.9-1.1Msun and a secondary star of M_{2}=0.08-0.11Msun.
2009-01-01
We present deep XMM-Newton European Photon Imaging Camera spectroscopic and timing X-ray observations of the nearby solitary radio millisecond pulsar, PSR J0030+0451. Its emission spectrum in the 0.1-10 keV range is found to be remarkably similar to that of the nearest and best-studied millisecond pulsar, PSR J0437-4715, being well described by a predominantly thermal two-temperature model plus a faint hard tail evident above approx2 keV. The pulsed emission in the 0.3-2 keV band is characterized by two broad pulses with pulsed fraction approx60%-70%, consistent with a mostly thermal origin of the X-rays only if the surface polar cap radiation is from a light-element atmosphere. Modeling of the thermal pulses permits us to place constraints on the neutron star radius of R
A deep XMM-Newton survey of M 31
2007-11-26
The deep homogeneous survey of the large Local-Group spiral galaxy M 31 is a milestone project for X-ray astronomy, as it allows a detailed X-ray inventory of an archetypal low-star-formation-rate galaxy like our own. We present first results of the deep XMM-Newton survey, which covers the entire D 25 ellipse. Information from different X-ray energy bands are combined in an X-ray colour image of M 31. In the first 15 observations we found about 1000 sources, the full survey will yield about 2000 X-ray sources. Sources will be classified using hardness ratios, extent, high quality spectra and time variability. In addition the sources will be correlated with catalogues in optical, infra-red and radio wavelengths. Our goal is to study M 31 X-ray binaries and globular cluster sources, supersoft sources, supernova remnants and the hot interstellar medium and separate them from foreground stars and background objects.
2009-01-01
We present the results of X-ray spectral analysis of 22 active galactic nuclei (AGNs) with a small scattering fraction selected from the Second XMM-Newton Serendipitous Source Catalogue using hardness ratios. They are candidates of buried AGNs, since a scattering fraction, which is a fraction of scattered emission by the circumnuclear photoionized gas with respect to direct emission, can be used to estimate the size of the opening part of an obscuring torus. Their X-ray spectra are modeled by a combination of a power law with a photon index of 1.5-2 absorbed by a column density of approx1023-24 cm-2, an unabsorbed power law, narrow Gaussian lines, and some additional soft components. We find that scattering fractions of 20 among 22 objects are less than a typical value (approx3%) for Seyfert 2s observed so far. In particular, ...
Fabrication of Efficient, Large Aperture Transmission Diffraction Gratings by Ion-Beam Etching
2000-01-01
The utilization of high-power short pulse laser employing chirped-pulse amplification (CPA) for material processing and inertial confinement research is widely increasing. The performance of these high-power CPA laser system continues to be limited by the ability of the pulse compression gratings to hold up to the high-average-power or high-peak-power of the laser. Pulse compression gratings used in transmission and fabricated out of bulk fused silica have intrinsically the highest laser damage threshold when compared with metal or multilayer dielectric gratings that work in reflection. LLNL has developed processing capability to produce high efficiency fused silica transmission gratings at sizes useful to future Petawatt-class systems, and has demonstrated high efficiency at smaller aperture. This report shows that fused silica diffraction exhibiting
Degenerate four-wave mixing mediated by ponderomotive-force-driven plasma gratings
2007-01-01
Degenerate four-wave mixing mediated by ponderomotive-force-driven plasma gratings is demonstrated in the near-infrared regime. The quadratic dependence of the reflectivity of the probe pulse on plasma density indicates that the mixing is caused by the quasineutral plasma grating driven by the laser ponderomotive force. The experiment verifies that ponderomotive force is an effective means to produce a large-amplitude short-period plasma grating, which has many important applications in ultrahigh-intensity optics. In particular, such a grating is a crucial element for the development of plasma phase-conjugate mirrors that can be used to restore the wave-front distortion that is ubiquitous in nonlinear propagation
2010-01-01
Radiation-mode coupling is stronger and more efficient in tilted fiber Bragg gratings than in other fiber gratings; it has good advantage in such fields as optical communication and optical sensors. A simplified coupled-mode theory (CMT) approach is proposed for what we believe to be the first time, whose validity is demonstrated by comparing its simulation results with that of the complete CMT equations. With the simplified CMT approach, a theoretical spectral analysis of coupling from core mode to counter-propagating radiation modes in reflective tilted fiber Bragg gratings is presented. The influence of grating length, refractive index modulation amplitude and tilt angle is exhaustively investigated on the transmission spectrum characteristics. The different dependences between s-polari...
GRO J1655-40: from ASCA and XMM-Newton Observations
2007-04-07
We have analysed four ASCA observations (1994--1995, 1996--1997) and three XMM-Newton observations (2005) of this source, in all of which the source is in high/soft state. We modeled the continuum spectra with relativistic disk model kerrbb, estimated the spin of the central black hole, and constrained the spectral hardening factor f_col and the distance. If kerrbb model applies, for normally used value of f_col, the distance cannot be very small, and f_col changes with observations.
An SZ/X-ray galaxy cluster model and the X-ray follow-up of the Planck clusters
2008-05-29
Sunyaev-Zel'dovich (SZ) cluster surveys will become an important cosmological tool over next few years, and it will be essential to relate these new surveys to cluster surveys in other wavebands. We present an empirical model of cluster SZ and X-ray observables constructed to address this question and to motivate, dimension and guide X-ray follow-up of SZ surveys. As an example application of the model, we discuss potential XMM-Newton follow-up of Planck clusters.
A systematic study of low-mass X-ray binaries in the M31 globular cluster system
2010-01-01
ABSTRACT We investigate low-mass X-ray binaries (LMXBs) in the M31 globular cluster (GC) system using data from the 2XMMi catalogue. These X-ray data are based on all publicly available XMM-Newton observations of the galaxy. This new survey provides the most complete and homogeneous X-ray survey of M31's GCs to date, covering
A Search for New Galactic Magnetars in Archival Chandra and XMM-Newton Observations
2007-11-08
We present constraints on the number of Galactic magnetars, which we have established by searching for sources with periodic variability in 506 archival Chandra observations and 441 archival XMM-Newton observations of the Galactic plane (|b|1e5 yr. Obtaining better constraints will require wide-field X-ray or radio searches for transient X-ray pulsars similar to XTE J1810--197, AX J1845.0--0250, CXOU J164710.2--455216, and 1E 1547.0-5408.
XMM-Newton observations of HD189733 during planetary transits
2010-08-24
We report on two XMM-Newton observations of the planetary host star HD189733. The system has a close in planet and it can potentially affect the coronal structure via interactions with the magnetosphere. We have obtained X-ray spectra and light curves from EPIC and RGS on board XMM-Newton which we have analyzed and interpreted. We reduced X-ray data from primary transit and secondary eclipse occurred in April 17th 2007 and May 18th 2009, respectively. In the April 2007 observation only variability due to weak flares is recognized. In 2009 HD189733 exhibited a X-ray flux always larger than in the 2007 observation. The average flux in 2009 was higher than in 2007 observation by a factor of 45%. During the 2009 secondary eclipse we observed a softening of the X-ray spectrum significant at level of ~3 sigma. Further, we observed the most intense flare recorded at either epochs. This flare occurred 3 ks after the end of the eclipse.The flare decay shows several minor ignitions perhaps linked to the main event and hinting for secondary loops that emit triggered by the main loop. Magneto-Hydro-Dynamical (MHD) simulations show that the magnetic interaction between planet and star enhances the density and the magnetic field in a region comprised between the planet and the star because of their relative orbital/rotation motion. X-ray observations and model predictions are globally found in agreement, despite the quite simple MHD model an d the lack of precise estimate of parameters including the alignment and the intensity of stellar and planetary magnetic fields. Future observations should confirm or disprove this hypothesis, by determining whether flares are systematically recurring in the light curve at the same planetary phase.
XMM-Newton Observations of the Nuclei of the Radio Galaxies 3C 305, DA 240, and 4C 73.08
2008-08-05
We present new XMM-Newton EPIC observations of the nuclei of the nearby radio galaxies 3C 305, DA 240, and 4C 73.08, and investigate the origin of their nuclear X-ray emission. The nuclei of the three sources appear to have different relative contributions of accretion- and jet-related X-ray emission, as expected based on earlier work. The X-ray spectrum of the FRII narrow-line radio galaxy (NLRG) 4C 73.08 is modeled with the sum of a heavily absorbed power law that we interpret to be associated with a luminous accretion disk and circumnuclear obscuring structure, and an unabsorbed power law that originates in an unresolved jet. This behavior is consistent with other narrow-line radio galaxies. The X-ray emission of the low-excitation FRII radio galaxy DA 240 is best modeled as an unabsorbed power law that we associate with a parsec-scale jet, similar to other low-excitation sources that we have studied previously. However, the X-ray nucleus of the narrow-line radio galaxy 3C 305 shows no evidence for the heavily absorbed X-ray emission that has been found in other NLRGs. It is possible that the nuclear optical spectrum in 3C 305 is intrinsically weak-lined, with the strong emission arising from extended regions that indicate the presence of jet--environment interactions. Our observations of 3C 305 suggest that this source is more closely related to other weak-lined radio galaxies. This ambiguity could extend to other sources c urrently classified as NLRGs. We also present XMM-Newton and VLA observations of the hotspot of DA 240, arguing that this is another detection of X-ray synchrotron emission from a low-luminosity hotspot.
The Complex X-ray Spectrum of the Sefyert 1.5 Source NGC 6860
2010-06-24
The X-ray spectrum of the Seyfert 1.5 source NGC 6860 is among the most complex of the sources detected in the Swift Burst Alert Telescope all-sky survey. A short XMM-Newton follow-up observation of the source revealed a flat spectrum both above and below 2 keV. To uncover the complexity of the source, in this paper we analyze both a 40 ks Suzaku and a 100 ks XMM-Newton observation of NGC 6860. While the spectral state of the source changed between the newer observations presented here and the earlier short XMM-Newton spectrum - showing a higher flux and steeper power law component - the spectrum of NGC 6860 is still complex with clearly detected warm absorption signatures. We find that a two component warm ionized absorber is present in the soft spectrum, with column densities of about 10^20 and 10^21 cm$^-2, ionization parameters of xi = 180 and 45 ergs cm s^-1, and outflow velocities for each component in the range of 0-300 km s^-1. Additionally, in the hard spectrum we find a broad (approx 11000 km s^-1) Fe K-alpha emission line, redshifted by approx 2800 km s^-1.
Spatially resolved X-ray spectra of NGC 4258
2007-01-19
We report a spatially resolved, X-ray spectral analysis of NGC 4258 using archival {\\it Chandra} and {\\it XMM-Newton} observations. The {\\it XMM-Newton} spectra of the nuclear region are well described by two power-law components, a soft (0.57 keV) thermal component, and an Fe K$\\alpha$ line with EW = 40 $\\pm$ 33 eV. The properties of the second, weaker power-law component are similar to those of an off-nuclear source $2.5\\arcsec$ SW of the nucleus. The spectrum of the extended emission of the entire galaxy is well described by two thermal components (MEKAL) models with temperatures $\\simeq 0.60$ and 0.22 keV. The {\\it Chandra} and {\\it XMM-Newton} spectra along the anomalous arms show that the absorbing column density to the SE anomalous arm is consistent with absorption by gas in our Galaxy, while the absorbing column to the NW anomalous arm is higher, indicating that the NW arm is partially on the far side of the galactic disk. The combined {\\it Chandra} data clearly detect the X-ray emission from the hot spots at the end of the approximately N-S radio jets. By assuming the hot spots represent shocked thermal gas at the ends of the jets, we estimate shock powers of $\\simeq 3 \\times 10^{39} f^{-1/2}$ \\ergps ($f $ is the filling factor), similar to the radiative power in the inner anomalous arms, consistent with the notion that the jets could be responsible for heating the gas in the anomalous arms.
2007-03-06
Context: Power density spectra (PDS) that are characteristic of low mass X-ray binaries (LMXBs) have been previously reported for M31 X-ray sources, observed by XMM-Newton. However, we have recently discovered that these PDS result from the improper addition/subtraction of non-simultaneous lightcurves. Aims: To understand the properties and origins of the artefact. Methods: We re-analysed our XMM-Newton observations of M31 with non-simultaneous and simultaneous lightcurves, then combined simulated lightcurves at various intensities with various offsets and found that the artefact is more dependent on the offset than the intensity. Results: The lightcurves produced by the XMM-Newton Science Analysis Software (SAS) are non-synchronised by default. This affects not only the combination of lightcurves from the three EPIC detectors (MOS1, MOS2 and pn), but also background subtraction in the same CCD. It is therefore imperative that all SAS-generated lightcurves are synchronised by time filtering, even if the whole observation is to be used. We also find that the reported timing behaviour for NGC 4559 ULX-7 was also contaminated by the artefact; there is no significant variability in the correctly-combined lightcurves of NGC 4559 ULX-7. Hence, the classification of this source as an intermediate-mass black hole is no longer justified. Conclusions: While previous timing results from M31 have been proven wrong, and also the broken power law PDS in NGC 4559 ULX-7, XMM-Newton was able to detect aperiodic variability in just 3 ks of observations of NGC 5408 ULX1. Hence XMM-Newton remains a viable tool for analysing variability in extra-galactic X-ray sources.
2009-04-27
The radio-quiet neutron star 1E1207.4-5209 has been the target of several XMM-Newton observations, with a total exposure of ~350 ks. The source is located at intermediate galactic latitude (b~10 degrees), i.e. in a sky region with an extremely interesting mix of both galactic and extra-galactic X-ray sources. The aim of our work is to investigate the properties of both the intermediate-latitude galactic and extra-galactic X-ray source populations in the 1E1207.4-5209 field. We performed a coherent analysis of the whole XMM-Newton observation data set to build a catalogue of serendipitous X-ray sources detected with high confidence and to derive information on the source flux, spectra, and time variability. In addition, we performed a complete multi-band (UBVRI) optical coverage of the field with the Wide Field Imager (WFI) of the ESO/MPG 2.2m telescope (La Silla) to search for candidate optical counterparts to the X-ray sources, down to a V-band limiting magnitude of ~24.5. We detected a total of 144 serendipitous X-ray sources. Thanks to the refined X-ray positions and to the WFI observations, we found candidate optical counterparts for most of the X-ray sources in our compilation. For most of the brightest ones we proposed a likely classification based on both the X-ray spectra and the optical colours. Our results indicate that at intermediate galactic latitude the X-ray source population is dominated by the extra-galactic co mponent, but with a significant contribution from the galactic component in the soft energy band, below 2 keV.
Bragg Grating Simulation Software.
2008-01-01
This document is a user manual for a software application that predicts the complex reflection spectrum of fibre Bragg gratings, given user defined input parameters. The software is designed primarily to complement the joint DSTO/Swinburne grating writing facility (FigFab) and can be used to determine the optimum writing variables to achieve a required grating reflection profile. Alternatively the software can be used to simulate the intensity and phase information for use in other Bragg grating sensing applications such as intragrating strain profiling.DCDS (PHS)In recent years, there has been a growing requirement for Bragg grating sensors to support a number of widely differing tasks across several divisions in the DSTO. This requirement had previously been met by outsourcing to commercial companies. However in 2002, the DSTO invested in a research capability located at Swinburne University of Technology, which now allows DSTO staff to fabricate their own gratings to specific requirements. This document is an operation manual for custom-designed simulation software to predict the performance of fibre Bragg gratings, given user defined input parameters. The software is designed primarily to complement the joint DSTO/Swinburne grating writing facility (FigFaB) and can be used to determine the optimum writing parameters to achieve a required grating profile. Alternatively, the software can be used to simulate the intensity and phase information for use in other Bragg grating sensing applications such as intragrating distributed measurements. Contributor: AVD; Air Vehicles Division; Chief, Air Vehicles Division Format: 23; 0 Other identifier: AR-014-091; 2007/1105304/1; DSTO-TN-0800; LRR06/063
Ultra-Compact Planar Grating Multiplexers Using Silicon Platforms
2010-01-01
Compact planar grating demultiplexers are designed and fabricated using silicon wafers. The demultiplexers have a much more compact size compared to conventional silica-based devices. The dimension of the devices is around half a millimeter. Demultiplexers with both echelle and total internal reflection facets are characterized. The loss of demultiplexers using total internal reflection facets will be 3-5 dB lower than that using echelle facets. It is shown that sidewall roughness of grating facets results in most of the loss for fabricated samples. The noise floor of amorphous silicon-based grating demultiplexers is relatively high for practical applications. Appropriate annealing can be used to reduce the noise floor.
2009-01-01
Quasi-distributed sensors based on Fibre Bragg Gratings (FBG) usually deal with the concatenation of FBGs of different Bragg wavelengths analyzed through wavelength-sensitive devices. In these sensors, a given wavelengths range is dedicated to one particular FBG. The number of sensing points is directly limited by the source and detector spectral ranges, and by the wavelength spacing between two gratings. This spacing is linked to the maximum possible excursion of the physical parameter to be measured-before superimposition of the reflection spectra of the FBGs. In this paper, an original interrogating device is presented, that allows a very large number of concatenated gratings to be addressed. In this scheme, identical FBGs (same Bragg wavelength and same low reflectivity) are interrogat...
2005-01-01
Sub-micrometer periodic gratings were generated on thin poly-carbonate films spin-coated onto thin flat silver layer covered BK7 substrates by two-beam interference realized with the fourth harmonic of the Nd:Yag laser. The 416 nm period of the laser-induced grating was half of the applied master grating, the modulation depth was increased by the number of laser pulses at a given intensity. Attenuated total reflection measurements were performed in case of plasmon propagation directions parallel and perpendicular to the grooves, and on rotated gratings oriented at angles making the grating coupling effect detectable. Atomic force microscopy (AFM) was applied to determine the modulation depth of the gratings. It was shown that the periodically corrugated polymer surfaces resulted in the coupling of the surface plasmons already when the structure period was very close ...
Fiber Bragg gratings in polarization maintaining specialty fiber for Raman fiber lasers
2010-01-01
The fabrication of fiber Bragg gratings (FBG) in highly nonlinear specialty fibers for Raman fiber lasers (RFL) is described. Besides the special properties of FBGs in polarization maintaining (PM) fibers that have to be considered with regard to an optimized laser performance, a method for the post-fabrication tuning of the grating reflectivity by exploiting the nonlinear photosensitivity characteristic of the fiber is presented. Experimental results for a RFL setup with a cavity length of 3 m and FBGs directly inscribed into the active Raman fiber are discussed.
Evaluation of a moire imaging system
1979-01-01
Moire fringe techniques can be used to measure surface topography. The factors that affect the formation of the fringes have been assessed theoretically by developing models of gratings and light sources of finite dimensions. In this way the effect of parameters such as the intensity distribution of the light source, the viewing aperture function, the lateral displacement of the source relative to the viewing axis, the viewing distance, the grating spacing and grating ratio have been evaluated. Other factors, related to the physical properties and geometry of the reflecting surface, have also been investigated. Suggestions are made for the design of an optimum moire imaging system. (author)
Design of a mid-IR immersion echelle grating spectrograph for remote sensing
1995-05-09
We describe the design of a silicon immersion grating spectrograph for the remote detection of chemicals in the atmosphere. The instrument is designed to operate in the two atmospheric windows from 2.3 to 2.5 and 2.8 and 4.2 microns at a resolution of 0.1 cm{sup {minus}1}. This is achieved by cross dispersing a high order silicon immersion echelle (13.5 grooves/mm) and a first order concave grating operating in a reflective configuration to generate a two-dimensional spectrum in the image plane with diffraction limited performance.
2009-01-01
Reflective diffraction gratings enable novel optical configurations that simplify and improve laser interferometers. We have proposed an all-reflective grating interferometer that can be used in LISA type interferometers for space gravitational wave detection [1]. One configuration requires a highly polarization sensitive grating. We report on characterizations of a grating made atop high reflective dielectric layers. Using a direct measurement method, the diffraction efficiency at the Littrow angle for s-polarization is measured as 97.3% and for p-polarization 4.2%, leading to a s/p polarization diffraction ratio of 23.2. The depolarization from s- to p-polarization is measured to be approx1.7x10-4, and from p- to s-polarization 1.8x10-4. We derived a transfer matrix based on these measurements. Furthermore, we have developed a more ...
Quantum reflection of helium atom beams from a microstructured grating
2008-07-01
We observe high-resolution diffraction patterns of a thermal-energy helium-atom beam reflected from a microstructured surface grating at grazing incidence. The grating consists of 10-$\\mu$m-wide Cr strips patterned on a quartz substrate and has a periodicity of 20 $\\mu$m. Fully-resolved diffraction peaks up to the $7^{\\rm th}$ order are observed at grazing angles up to 20 mrad. With changes in de Broglie wavelength or grazing angle the relative diffraction intensities show significant variations which shed light on the nature of the atom-surface interaction potential. The observations are explained in terms of quantum reflection at the long-range attractive Casimir-van der Waals potential.
This paper describes the use of a fiber optic system to measure strain at thousands of locations along optical fibers where weakly reflecting Bragg gratings have been photoetched. The optical fibers were ...
Some considerations on uv optics for synchrotron radiation
Special problems of radiation shorter than about 2000A are discussed. Basic optics principles are reviewed, including the critical angle, total reflection, ''order sorting,'' and mirror configuration. The power present in the beam of synchrotron radiation is considered. Ray tracing mirrors and gratings is addressed in some detail. Finally, ray tracing is applied to a hypothetical toroidal grating monochromator. 6 figures. (RWR)
Some considerations on uv optics for synchrotron radiation
1978-08-01
Special problems of radiation shorter than about 2000A are discussed. Basic optics principles are reviewed, including the critical angle, total reflection, ''order sorting,'' and mirror configuration. The power present in the beam of synchrotron radiation is considered. Ray tracing mirrors and gratings is addressed in some detail. Finally, ray tracing is applied to a hypothetical toroidal grating monochromator. 6 figures. (RWR)
On metallic gratings coated conformally with isotropic negative-phase-velocity materials
2007-11-01
Application of the differential method (also called the C method) to plane-wave diffraction by a perfectly conducting, sinusoidally corrugated metallic grating coated with a linear, homogeneous, isotropic, lossless dielectric-magnetic material shows that coating materials with negative index of refraction may deliver enhanced maximum nonspecular reflection efficiencies in comparison to coating materials with positive index of refraction.
2006-01-01
It is shown from both a phenomenological study and exact modeling that the reason for the experimentally observed substantial (a few angstroms or nanometers) separation in wavelength between the maxima of the inside (negative numbered) and outside (positive numbered) diffraction orders of a multilayer-coated grating, operating at near normal incidence and close to the Bragg condition in the soft-x-ray and extreme-ultraviolet (EUV) regions, is related to the different angles of deviation of the orders. This wavelength separation is also a feature of uncoated diffraction gratings, although not clearly noticeable. The widely used approximate approach for calculating the absolute efficiency, the product of the relative grating efficiency and the reflectance of its multilayer coating, has until recently been considered accurate enough for the analysis of soft-x-ray ...
2010-01-01
We present a method to explore the full sensitivity of grating coupled surface plasmon resonance (GCSPR) sensors on an azimuthally rotatable grating by optimizing the polarization angle of the incident light. This is the condition where double surface plasmons polaritons (SPPs) can be excited by a single wavelength [1]. This configuration provides a sensitivity up to 950^o/RIU compared to a system without azimuthal control [2]. We show here that the sensitivity of this configuration is only achievable when the polarization angle of the incident light is optimized. This is due to the excitation of a fully coupled SPP (as can be observed as a deeper dip in the reflectivity spectra) which is only possible using the optimized polarization angle in an azimuthally rotated grating. This result in...
2010-01-01
Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous wave source. In both cases, the spin-echo polarization, studied as a function of the spin-echo length, peaks at integer multiples of the grati...
Aplanatic grazing incidence diffraction grating: a new optical element
We present the theory of a grazing incidence reflection grating capable of imaging at submicron resolution. The optic is mechanically ruled on a spherical or cylindrical surface with varied groove spacings, delivering diffraction-limited response and a wide field of view at a selected wavelength. Geometrical aberrations are calculated on the basis of Fermat's principle, revealing significant improvements over a grazing incidence mirror. Aplanatic and quasi-aplanatic versions of the grating have applications in both imaging and scanning microscopes, microprobes, collimators, and telescopes. A 2-D crossed system of such gratings, similar to the grazing incidence mirror geometry of Kirkpatrick and Baez, could potentially provide spatial resolutions of --200 A.
Aplanatic grazing incidence diffraction grating: a new optical element
1986-09-15
We present the theory of a grazing incidence reflection grating capable of imaging at submicron resolution. The optic is mechanically ruled on a spherical or cylindrical surface with varied groove spacings, delivering diffraction-limited response and a wide field of view at a selected wavelength. Geometrical aberrations are calculated on the basis of Fermat's principle, revealing significant improvements over a grazing incidence mirror. Aplanatic and quasi-aplanatic versions of the grating have applications in both imaging and scanning microscopes, microprobes, collimators, and telescopes. A 2-D crossed system of such gratings, similar to the grazing incidence mirror geometry of Kirkpatrick and Baez, could potentially provide spatial resolutions of --200 A.
Website Policies and Important Links Comments
 |
 |
 |
WorldWideScience.org is maintained by the
U.S. Department of Energy's
Office of Scientific and Technical Information as the Operating Agent
for the WorldWideScience Alliance.