XMM-Newton European Photon Imaging Camera Research Articles

Chemical Enrichment Study of Abell 3112 Galaxy Cluster with XMM-Newton

Galaksi kümeleri, evrendeki kütleçekimsel olarak bağlı en büyük yapılardır. Her biri milyonlarca yıldıza sahip olan yüzlerce galaksi içeriyor olsalar da, galaksi kümelerini oluşturan baryonik maddenin büyük kısmı kümeye yayılmış olan sıcak, iyonize gaz halindedir (genel olarak "intracluster medium" veya basitçe "ICM" şeklinde bahsedilir). Sıcaklığı milyonkelvin mertebesine ulaşan ICM gazı X-ışını ışıması yapar. ICM gazının X-ışın tayfı, bize gazın kimyasal özellikleri ve ICM'de dağılımını bulmamızı sağlayan metal emisyon çizgileri de barındırır. Bu çalışmada, XMM-Newton European Photon Imaging Camera (EPIC) verilerini kullanarak zengin bir galaksi kümesi olan A3112 (z=0.07525)'nin kimyasal yapısını inceliyoruz. Modelimiz, çekirdekte yüksek metal bolluğu ve düşük kT değeri göstermekte, bu da A3112'nin rahatlamış ve soğuk çekirdekli bir küme olduğuna işaret etmektedir.

Chemical enrichment of ICM within the Centaurus cluster – I. Radial profiles

ABSTRACT We examine deep XMM–Newton European Photon Imaging Camera pn observations of the Centaurus cluster to study the hot intracluster medium (ICM) and radial metal distributions within such an environment. We found that the best-fitting spectral model corresponds to a lognormal temperature distribution, with discontinuities around ∼10, ∼50, and ∼100 kpc, also observed in the abundance distributions. We measured the radial profiles of O, Si, S, Ar, Ca, and Fe. These profiles reveal prominent negative gradients for distances <90 kpc, which then transition to flatter profiles. We modelled X/Fe ratio profiles with a linear combination of core-collapse supernova and Type Ia supernova (SNIa) models. The best-fitting model suggests a uniform SNIa percentage contribution to the total cluster enrichment, thus supporting an early enrichment of the ICM, with most of the metals present being produced before clustering.

An XMM-Newton EPIC X-Ray View of the Symbiotic Star R Aquarii

Abstract We present the analysis of archival XMM-Newton European Photon Imaging Camera (EPIC) X-ray observations of the symbiotic star R Aquarii. We used the Extended Source Analysis Software package to disclose diffuse soft X-ray emission extending up to 2.′2 (≈0.27 pc) from this binary system. The depth of these XMM-Newton EPIC observations reveals in unprecedented detail the spatial distribution of this diffuse emission, with a bipolar morphology spatially correlated with the optical nebula. The extended X-ray emission shares the same dominant soft X-ray-emitting temperature as the clumps in the jet-like feature resolved by Chandra in the vicinity of the binary system. The harder component in the jet might suggest that the gas cools down; however, the possible presence of nonthermal emission produced by the presence of a magnetic field collimating the mass ejection cannot be discarded. We propose that the ongoing precessing jet creates bipolar cavities filled with X-ray-emitting hot gas that feeds the more extended X-ray bubble as they get disrupted. These EPIC observations demonstrate that the jet feedback mechanism produced by an accreting disk around an evolved, low-mass star can blow hot bubbles, similar to those produced by jets arising from the nuclei of active galaxies.

X-ray observations of the nova shell IPHASX J210204.7+471015

ABSTRACT We present the analysis of XMM–Newton European Photon Imaging Camera (EPIC) observations of the nova shell IPHASX J210204.7+471015. We detect X-ray emission from the progenitor binary star with properties that resemble those of underluminous intermediate polars such as DQ Herculis (DQ Her): an X-ray-emitting plasma with temperature of TX = (6.4 ± 3.1) × 106 K, a non-thermal X-ray component, and an estimated X-ray luminosity of LX = 1030 erg s−1. Time series analyses unveil the presence of two periods, the dominant with a period of 2.9 ± 0.2 h, which might be attributed to the spin of the white dwarf, and a secondary of 4.5 ± 0.6 h that is in line with the orbital period of the binary system derived from optical observations. We do not detect extended X-ray emission as in other nova shells probably due to its relatively old age (130–170 yr) or to its asymmetric disrupted morphology that is suggestive of explosion scenarios different to the symmetric ones assumed in available numerical simulations of nova explosions.

X-Ray Reprocessing: Through the Eclipse Spectra of High-mass X-Ray Binaries with XMM-Newton

Abstract The study of X-ray reprocessing is one of the key diagnostic tools to probe the environment in X-ray binary systems. One difficult aspect of studying X-ray reprocessing is the presence of much brighter primary radiation from the compact star together with the reprocessed radiation. In contrast, for eclipsing systems, the X-rays we receive during eclipse are only those produced by the reprocessing of the emission from the compact star by the surrounding medium. We report results from a spectral study of the X-ray emission during eclipse and outside eclipse in nine high-mass X-ray binaries (HMXBs) with the XMM-Newton European Photon Imaging Camera (EPIC) pn to investigate different aspects of the stellar wind in these HMXBs. During eclipse the continuum component of the spectrum is reduced by a factor of ∼8–237, but the count rate for the 6.4 keV iron emission line or the complex of iron emission lines in HMXBs is reduced by a smaller factor, leading to large equivalent widths of the iron emission lines. This indicates a large size for the line emission region, comparable to or larger than the companion star in these HMXB systems. However, there are significant system to system differences. 4U 1538−522, despite having a large absorption column density, shows a soft emission component with comparable flux during the eclipse and out-of-eclipse phases. Emission from hydrogen-like iron has been observed in LMC X-4 for the first time, in the out-of-eclipse phase in one of the observations.. Overall, we find significant differences in the eclipse spectrum of different HMXBs and also in their eclipse spectra against out-of-eclipse spectra.

X-ray photometry

Abstract I describe a method for synthesizing photometric passbands for use with current and future X-ray instruments. The method permits the standardization of X-ray passbands and thus X-ray photometry between different instruments and missions. The method is illustrated by synthesizing a passband in the XMM–Newton European Photon Imaging Camera pn which is similar to the ROSAT Position Sensitive Proportional Counter 0.5–2 keV band.

A NEW METHOD TO CONSTRAIN SUPERNOVA FRACTIONS USING X-RAY OBSERVATIONS OF CLUSTERS OF GALAXIES

Supernova (SN) explosions enrich the intra-cluster medium (ICM) both by creating and dispersing metals. We introduce a method to measure the number of SNe and relative contribution of Type Ia supernovae (SNe Ia) and core-collapse supernovae (SNe cc) by directly fitting X-ray spectral observations. The method has been implemented as an XSPEC model called snapec. snapec utilizes a single temperature thermal plasma code (apec) to model the spectral emission based on metal abundances calculated using the latest SN yields from SN Ia and SN cc explosion models. This approach provides a self-consistent single set of uncertainties on the total number of SN explosions and relative fraction of SN types in the ICM over the cluster lifetime by directly allowing these parameters to be determined by SN yields provided by simulations. We apply our approach to the XMM-Newton European Photon Imaging Camera (EPIC), Reflection Grating Spectrometer (RGS), and 200 ks simulated Astro-H observations of a cooling flow cluster, A3112. We find that various sets of SN yields present in the literature produce an acceptable fit to the EPIC and RGS spectra of A3112. We infer that 30.3% +/- 5.4% of the total SN explosions are SNe Ia, and the total number of SN explosions required to create the observed metals is in the order of (1.06 +/- 0.34)*10^{9}, from snapec fits to RGS spectra. These values may be compared to the enrichment expected based on well-established empirically-measured SN rates per star formed. The proportions of SNe Ia and SNe cc inferred to have enriched the ICM in the inner 52 kpc of A3112 is consistent with these specific rates, if one applies a correction for the metals locked up in stars. At the same time, the inferred level of SN enrichment corresponds to a star-to-gas mass ratio that is several times greater than the 10% estimated globally for clusters in the A3112 mass range.

HIGH-RESOLUTIONXMM-NEWTONSPECTROSCOPY OF THE COOLING FLOW CLUSTER A3112

We examine high signal to noise XMM-Newton European Photon Imaging Camera (EPIC) and Reflection Grating Spectrometer (RGS) observations to determine the physical characteristics of the gas in the cool core and outskirts of the nearby rich cluster A3112. The XMM-Newton Extended Source Analysis Software data reduction and background modeling methods were used to analyze the XMM- Newton EPIC data. From the EPIC data we find that the iron and silicon abundance gradients show significant increase towards the center of the cluster while the oxygen abundance profile is centrally peaked but has a shallower distribution than that of iron. The X-ray mass modeling is based on the temperature and deprojected density distributions of the intra-cluster medium determined from EPIC observations. The total mass of A3112 obeys the M-T scaling relations found using XMM-Newton and Chandra observations of massive clusters at R500. The gas mass fraction f_gas= 0.149^{+0.036}_{-0.032} at R500, is consistent with the seven-year WMAP results. The comparisons of line fluxes and flux limits on the Fe XVII and Fe XVIII lines obtained from high resolution RGS spectra indicate that there is no spectral evidence for cooler gas associated with the cluster with temperature below 1.0 keV in the central <38" (\sim 52 kpc) region of A3112. High resolution RGS spectra also yield an upper limit to the turbulent motions in compact core of A3112 (206 km/s). We find that the energy contribution of turbulence to total energy is less than 6 per cent. This upper limit is consistent with the amount of energy contribution measured in recent high resolution simulations of relaxed galaxy clusters.

Very fast photometric and X-ray observations of the intermediate polar V2069 Cygni (RX J2123.7+4217)

We present fast timing photometric observations of the intermediate polar V2069 Cygni (RX J2123.7+4217) using the Optical Timing Analyzer (OPTIMA) at the 1.3 m telescope of Skinakas Observatory. The optical (450-950 nm) light curve of V2069 Cygni was measured with sub-second resolution for the first time during July 2009 and revealed a double-peaked pulsation with a period of 743.38 +0.25. A similar double-peaked modulation was found in the simultaneous Swift satellite observations. We suggest that this period represents the spin of the white dwarf accretor. Moreover, we present the results from a detailed analysis of the XMM-Newton observation that also shows a double-peaked modulation, however shifted in phase, with 742.35 +0.23 s period. The X-ray spectra obtained from the XMM-Newton EPIC (European Photon Imaging Camera) instruments were modelled by a plasma emission and a soft black body component with a partial covering photo-electric absorption model with covering fraction of 0.65. An additional Gaussian emission line at 6.385 keV with an equivalent width of 243 eV is required to account for fluorescent emission from neutral iron. The iron fluorescence (~6.4 keV) and FeXXVI lines (~6.95 keV) are clearly resolved in the EPIC spectra. In the Porb-Pspin diagram of IPs, V2069 Cyg shows a low spin to orbit ratio of ~0.0276 in comparison with ~0.1 for other intermediate polars.

XMM-Newton observation of the eclipsing binary Algol

We present an XMM-Newton observation of the eclipsing binary Algol which contains an X-ray dark B8V primary and an X-ray bright K2IV secondary. The observation covered the optical secondary eclipse and captured an X-ray flare that was eclipsed by the B star. The XMM-Newton European Photon Imaging Camera and Reflection Grating Spectrometer spectra of Algol in its quiescent state are described by a two-temperature plasma model. The cool component has a temperature around 6.4 × 106K while that of the hot component ranges from 2 to 4.0 × 107K. Coronal abundances of C, N, O, Ne, Mg, Si and Fe were obtained for each component for both the quiescent and the flare phases, generally with upper limits for S and Ar, and upper limits for C, N, and O from the hot component. F-tests show that the abundances do not need to be different between the cool and the hot component and between the quiescent and the flare phase with the exception of Fe. Although the Fe abundance of the cool component remains constant at ∼0.14, the hot component shows an Fe abundance of ∼0.28, which increases to ∼0.44 during the flare. This increase is expected from the chromospheric evaporation model. The absorbing column density NH of the quiescent emission is 2.5 × 1020cm−2, while that of the flare-only emission is significantly lower and consistent with the column density of the interstellar medium. This observation substantiates earlier suggestions of the presence of X-ray absorbing material in the Algol system.

DEEPXMM-NEWTONSPECTROSCOPIC AND TIMING OBSERVATIONS OF THE ISOLATED RADIO MILLISECOND PULSAR PSR J0030+0451

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 ∼2 keV. The pulsed emission in the 0.3–2 keV band is characterized by two broad pulses with pulsed fraction ∼60%–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 > 10.7 (95% confidence) and R > 10.4 km (at 99.9% confidence) for M = 1.4 M☉.

RELATIVISTIC BROADENING OF IRON EMISSION LINES IN A SAMPLE OF ACTIVE GALACTIC NUCLEI

We present a uniform X-ray spectral analysis of eight type-1 active galactic nuclei (AGN) that have been previously observed with relativistically broadened iron emission lines. Utilizing data from the XMM-Newton European Photon Imaging Camera (EPIC-pn) we carefully model the spectral continuum, taking complex intrinsic absorption and emission into account. We then proceed to model the broad Fe K feature in each source with two different accretion disk emission line codes, as well as a self-consistent, ionized accretion disk spectrum convolved with relativistic smearing from the inner disk. Comparing the results, we show that relativistic blurring of the disk emission is required to explain the spectrum in most sources, even when one models the full reflection spectrum from the photoionized disk.

Simultaneous X-ray/optical/UV snapshots of active galactic nuclei fromXMM-Newton: spectral energy distributions for the reverberation mapped sample

We employ contemporaneous optical, ultraviolet (UV) and X-ray observations from the XMM–Newton European Photon Imaging Camera (EPIC-pn) and Optical Monitor (OM) archives to present, for the first time, simultaneous spectral energy distributions (SEDs) for the majority of the Peterson et al. reverberation mapped sample of active galactic nuclei (AGN). The raw data were reduced using the latest pipelines and are all analysed consistently. The virial mass estimates from Peterson et al. allow us to calculate Eddington ratios λEdd for the sample using the bolometric accretion luminosities determined directly from the SEDs. We calculate hard X-ray bolometric corrections κ2–10 keV for the sample and confirm a trend for increasing bolometric correction with Eddington ratio proposed in previous studies. Our comparison with previous work on these objects suggests that the OM bandpass may be less susceptible to intrinsic reddening than the far-UV peak of the thermal disc spectrum in AGN, yielding larger bolometric corrections than previous work: κ2–10 keV≈ 15–30 for λEdd≲ 0.1, κ2–10 keV≈ 20–70 for 0.1 ≲λEdd≲ 0.2 and κ2–10 keV≈ 70–150 for λEdd≳ 0.2, but part of this increase could be attributed to spectral complexity preventing accurate recovery of the intrinsic luminosity in some sources. Long-term optical–UV variability contributes a second order, but significant change to the total bolometric luminosity when comparing multiple observations for individual objects. We also consider the effect of a recently proposed correction for radiation pressure when determining black hole masses with reverberation mapping, and find that the revised mass estimates do not significantly alter the range of bolometric corrections seen but may yield a narrower distribution of Eddington ratios.

X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068

We use the full broad-band XMM-Newton European Photon Imaging Camera (EPIC) data to examine the X-ray spectrum of the nearby Seyfert 2 galaxy NGC 1068, previously shown to be complex with the X-ray continuum being a sum of components reflected/scattered from cold (neutral) and warm (ionized) matter, together with associated emission-line spectra. We quantify the neutral and ionized reflectors in terms of the luminosity of the hidden nucleus. Both are relatively weak, a result we interpret on the unified Seyfert model by a near side-on view to the putative torus, reducing the visibility of the illuminated inner surface of the torus (the cold reflector), and part of the ionized outflow. A high inclination in NGC 1068 also provides a natural explanation for the large (Compton-thick) absorbing column in the line-of-sight to the nucleus. The emission line fluxes are consistent with the strength of the neutral and ionized continuum components, supporting the robustness of the spectral model.

XMM-Newtonobservations of warm absorbers in PG quasars

We present XMM-Newton European Photon Imaging Camera observations of warm absorbers in the quasars PG 1114 + 445 and PG 1309 + 355, both of which exhibit evidence for absorption by warm material in the line of sight. We find the absorption in PG 1114 + 445 to be in two phases, a 'hot' phase with a log ionization parameter, xi, of 2.57, and a 'cooler' phase with log xi = 0.83; an unresolved transition array (UTA) of M-shell iron is observed in the cooler phase. The absorption in this quasar is similar to that observed in the Seyfert 1 NGC 3783. The absorption in PG 1309 + 355 consists of a single phase, with log xi = 1.87. The absorbing gas lies at distances of 10(18) -10(22) cm from the continuum radiation sources in these active galactic nuclei (AGN), which suggests that it could originate in a wind emanating from a molecular torus. We derive distances assuming that these X-ray warm absorbers have the same velocity as the ultraviolet warm absorbers observed in these quasars. The distances to the warm absorbers from the central continuum source scale approximately with the square root of the AGN ionizing luminosity, a result consistent with the warm absorber originating as a torus wind. The kinetic luminosities of these outflowing absorbers represent insignificant fractions (<10(-3)) of the energy budgets of the AGN.

XMM-Newtonobservations of high-luminosity radio-quiet quasi-stellar objects

XMM-Newton observations of five high-luminosity radio-quiet quasi-stellar objects (QSOs; Q 0144-3938, UM 269, PG 1634+706, SBS 0909+532 and PG 1247+267) are presented. Spectral energy distributions were calculated from the XMM-Newton European Photon Imaging Camera (EPIC) and Optical Monitor (OM) data, with bolometric luminosities estimated in the range from 7 x 10 45 to 2 × 10 48 erg s -1 for the sample, peaking in the ultraviolet. At least four of the QSOs show a similar soft excess, which can be well modelled by either one or two blackbody components, in addition to the hard X-ray power law. The temperatures of these blackbodies (∼100-500 eV) are too high to be direct thermal emission from the accretion disc, so Comptonization is suggested. Two populations of Comptonizing electrons, with different temperatures, are needed to model the broad-band spectrum. The hotter of these produces what is seen as the hard X-ray power law, while the cooler (∼0.25-0.5 keV) population models the spectral curvature at low energies. Only one of the QSOs shows evidence for an absorption component, while three of the five show neutral iron emission. Of these, PG 1247+267 seems to have a broad line (with an equivalent width of ∼250eV), with a strong, associated reflection component (R ∼ 2), measured out to 30 keV in the rest frame of the QSO. Finally, it is concluded that the X-ray continuum shape of active galactic nuclei remains essentially constant over a wide range of black hole mass and luminosity.

XMM-NewtonEPIC and Optical Monitor observations of Her X-1 over the 35-d beat period

We present the results of a series of XMM-Newton European Photon Imaging Camera (EPIC) and Optical Monitor observations of Her X-1, spread over a wide range of the 35-d precession period. We confirm that the spin modulation of the neutron star is weak or absent in the low state - in marked contrast to the main or short-on states. During the states of higher intensity, we observe a substructure in the broad soft X-ray modulation below ∼ 1 ke V, revealing the presence of separate peaks which reflect the structure seen at higher energies. The strong fluorescence emission line at ∼6.4 keV is detected in all observations (apart from one taken in the middle of eclipse), with higher line energy, width and normalization during the main-on state. In addition, we report the detection of a second line near 7 keV in 10 of the 15 observations taken during the low-intensity states of the system. This feature is rather weak and not significantly detected during the main-on state, when the strong continuum emission dominates the X-ray spectrum. Spin-resolved spectroscopy just after the rise to the main-on state shows that the variation of the Fe Kα at 6.4 keV is correlated with the soft X-ray emission. This confirms our past finding based on the XMM-Newton observations made further into the main-on state, and indicates the common origin for the thermal component and the Fe Kα line detected at these phases. We also find that the normalization of the 6.4-keV line during the low state is correlated with the binary orbital phase, having a broad maximum centred near φ oribit ∼ 0.5. We discuss these observations in the context of previous observations, investigate the origin of the soft and hard X-rays and consider the emission site of the 6.4-keV and 7-keV emission lines.

The complex FeK line of the Narrow-Line Seyfert 1 galaxy IRAS 13349+2438

The observation of the Narrow-Line Seyfert 1 galaxy IRAS 13349+2438 performed by XMM-Newton European Photon Imaging Camera between 0.3−10 keV, is presented here. The broadband spectrum of the source is dominated at low energies (E ≤ 2 keV) by a strong excess of emission and by complex emission/absorption features between ∼5.5−8.0 keV. The soft X-ray spectrum is consistent with ionized absorption found by the Reflection Grating Spectrometer (Sako et al. 2001a). We focus on the 2−10 keV spectrum which shows clear evidence for a broad, complex FeKα line, previously unseen by ASCA, and for an Fe K-shell edge detected at ∼7.3−7.4 keV (rest-frame). The presence of this edge could be explained by either partial covering or ionized/relativistic reflection models, with the latter being preferred and with a resulting power law slope of Γ ∼ 2.2. The line profile is complex, with a broad bump between ∼5.5−6.5 keV and a narrow emission line at ∼7 keV, separated by a sharp drop at ∼6.8 keV. This profile is compatible with two possible scenarios: i) a broad, ionized and gravitationally redshifted Laor diskline plus a narrow and ionized emission line; ii) a broad, ionized and single Schwarzschild (double-peaked) diskline with a superimposed narrow absorption line.

Iron K-features in the hard X-ray XMM-Newton spectrum of NGC 4151

Recent XMM–Newton observations have measured the hard (2.5–12 keV) X-ray spectrum of the well-known Seyfert galaxy NGC 4151 with a signal-to-noise unprecedented for this source. We find that a spectral model, developed to fit previous BeppoSAX and ASCA observations of NGC 4151, provides an excellent description of the XMM–Newton European Photon Imaging Camera (EPIC) data. The results support the view that it is the level of the continuum that is the main driver of the complex spectral variability exhibited by NGC 4151. We focus on the iron K-features in the NGC 4151 spectrum. There is no requirement for a relativistically broadened iron Kα line, in contrast to several earlier studies. The iron Kα-line profile is well modelled by a narrow Gaussian, the intensity of which varies by ∼25 per cent on time-scales of about a year. There is also a strong suggestion that the cold media present in the active nucleus of NGC 4151 have an iron abundance that is at least twice the solar value.

Fe K emission and absorption features in XMM-Newton spectra of Markarian 766: evidence for reprocessing in flare ejecta

We report on the analysis of a long XMM–Newton European Photon Imaging Camera (EPIC) observation in 2001 May of the narrow-line Seyfert 1 galaxy Markarian 766 (Mrk 766). The 3–11 keV spectrum exhibits a moderately steep power-law continuum, with a broad emission line at ∼6.7 keV, probably blended with a narrow line at ∼6.4 keV, and a broad absorption trough above ∼8.7 keV. We identify both broad spectral features with reprocessing in He-like Fe. An earlier XMM–Newton observation of Mrk 766 in 2000 May, when the source was a factor ∼2 fainter, shows a similar broad emission line, but with a slightly flatter power law and absorption at a lower energy. In neither observation do we find a requirement for the previously reported broad ‘red wing’ to the line and hence of reflection from the innermost accretion disc. More detailed examination of the longer XMM–Newton observation reveals evidence for rapid spectral variability in the Fe K band, apparently linked with the occurrence of X-ray ‘flares’. A reduction in the emission line strength and increased high-energy absorption during the X-ray flaring suggests that these transient effects are due to highly ionized ejecta associated with the flares. Simple scaling from the flare avalanche model proposed for the luminous quasi-stellar object PDS 456 confirms the feasibility of coherent flaring being the cause of the strong peaks seen in the X-ray light curve of Mrk 766.