Gulab C. Dewangan

Relativistic Iron K Emission and absorption in the Seyfert 1.9 galaxy MCG-5-23-16

We present the results of the simultaneous deep XMM-Newton and Chandra observations of the bright Seyfert 1.9 galaxy MCG -5-23-16, which is thought to have one of the best known examples of a relativistically broadened iron Kα line. The time-averaged spectral analysis shows that the iron K-shell complex is best modeled with an unresolved narrow emission component (FWHM < 5000 km s-1, EW ~ 60 eV) plus a broad component. This latter component has FWHM ~ 44,000 km s-1 and EW ~ 50 eV. Its profile is well described by an emission line originating from an accretion disk viewed with an inclination angle ~40°, with the emission arising from within a few tens of gravitational radii of the central black hole. The time-resolved spectral analysis of the XMM-Newton EPIC pn spectrum shows that both the narrow and broad components of the Fe K emission line appear to be constant in time within the errors. We detected a narrow sporadic absorption line at 7.7 keV, which appears to be variable on a timescale of 20 ks. If associated with Fe XXVI Lyα, this absorption is indicative of a possibly variable, high-ionization, high-velocity outflow. The variability of this absorption feature appears to rule out a local (z = 0) origin. The analysis of the XMM-Newton RGS spectrum reveals that the soft X-ray emission of MCG -5-23-16 is likely dominated by several emission lines superimposed on an unabsorbed scattered power-law continuum. The lack of strong Fe L-shell emission, together with the detection of a strong forbidden line in the O VII triplet, is consistent with a scenario in which the soft X-ray emission lines are produced in a plasma photoionized by the nuclear emission.

Black Hole Mass of the Ultraluminous X-Ray Source M82 X-1

We report the first clear evidence for the simultaneous presence of a low-frequency break and a QPO in the fluctuation power spectrum of a well-known ultraluminous X-ray source (ULX) in M82 using long XMM-Newton observations. The break occurs at a frequency of 34.2 mHz. The QPO has a centroid at νQPO = 114.3 ± 1.5 mHz, a coherence Q ≡ νQPO/ΔνFWHM 3.5, and an amplitude (rms) of 19% in the 2-10 keV band. The power spectrum is approximately flat below the break frequency and then falls off above the break frequency as a power law with the QPO superposed. This form of the power spectrum is characteristic of the Galactic X-ray binaries (XRBs) in their high or intermediate states. M82 X-1 was likely in an intermediate state during the observation. The EPIC pn spectrum is well described by a model comprising an absorbed power law (Γ ~ 2) and an iron line at ~6.6 keV with a width σ ~ 0.2 keV and an equivalent width of ~180 eV. Using the well-established correlations between the power and energy spectral parameters for XRBs, we estimate a black hole mass for M82 X-1 in the range of ~25-520 M☉, including systematic errors that arise due to the uncertainty in the calibration of the photon spectral index versus QPO frequency relation.

Early Ultraviolet, Optical, and X-Ray Observations of the Type IIP SN 2005cs in M51 with Swift

We report early photospheric-phase observations of the Type IIP supernova (SN) 2005cs obtained by the Swift ultraviolet-optical and X-ray telescopes. Observations started within 2 days of discovery and continued on a regular basis for 3 weeks. During this time the V-band magnitude remained essentially constant, while the UV was initially bright, but steadily faded until below the brightness of an underlying UV-bright H ii region. This UV decay is similar to SNe II observed bytheInternational Ultraviolet Explorer. UV grism spectra show the P Cygni absorption of Mgii 2798 8, indicating a photospheric origin of the UV flux. Based on non-LTE model atmosphere calculations with the CMFGEN code,weassociate therapidevolutionoftheUVfluxwiththecoolingoftheejecta,thepeakofthespectral energy distribution (SED) shifting from � 700 8 on June 30 to � 1200 8 on July 5. Furthermore, the corresponding recombination of the ejecta, e.g., the transition from Fe iii to Fe ii, induces a considerable strengthening of metal lineYblanketing at and above the photosphere, blocking more and more effectively this fading UV flux. SN 2005cs was not detected in the X-ray band, and the upper limit to the X-ray luminosity yields a limit to the mass-loss rate of theprogenitorof ˙ M P 1 ; 10 � 5 yr � 1 (vw/10kms � 1 ).Overall,Swiftrepresentsauniqueopportunitytocapturetheearly and fast evolution of Type II SNe in the UV, providing additional constraints on the reddening, the SED shortward of 4000 8, and the ionization state and temperature of the photon-decoupling regions. Subject headingg galaxies: individual (M51) — ultraviolet: general — X-rays: general Online material: color figures

An Investigation of the Origin of Soft X-Ray Excess Emission from Ark 564 and Mrk 1044

We investigate the origin of the soft X-ray excess emission from Ark 564 and Mrk 1044. Based on a long XMM-Newton observation of Ark 564, we find clear evidence for time delays such that the variations in the 4-10 kev band lag behind that in the 0.2-0.5 kev band by -->1768 ± 122 s. The full-band power density spectrum (PDS) of Ark 564 has a break at ~ -->1.2 × 1−3 Hz with power-law indices of ~1 and ~3 below and above the break. The hard (3-10 kev) band PDS is stronger and flatter than that in the soft (0.2-0.5) band. Based on a short XMM-Newton observation of Mrk 1044, we find no correlation between the 0.2-0.3 and 5-10 kev bands at zero lag. These observations imply that the soft excess is not the reprocessed hard X-ray emission. The EPIC-pn spectrum of Ark 564 is best described by a complex model consisting of optically thick Comptonization in a cool plasma for the soft excess and a steep power law, modified by two warm absorber media as inferred from the RGS data. The smeared wind and optically thick Comptonization models both describe the spectrum of Mrk 1044 satisfactorily, but the ionized reflection model requires extreme parameters. The data suggest two component coronas—a cool, optically thick corona for the soft excess and a hot corona for the power-law component. The existence of a break in the soft band PDS suggests a compact cool corona that can either be an ionized surface of the inner disk or an inner optically thick region coupled to a truncated disk.

XMM-Newton Observations of Broad Iron Kα Emission from Seyfert 1.9 Galaxy MCG –5-23-16

XMM-Newton observations of the bright Seyfert 1.9 galaxy MCG -5-23-16 have revealed a broad Fe Kα emission line that is nearly symmetric in contrast to the broad and redshifted asymmetric Fe Kα line sometimes observed from Seyfert 1 galaxies. The Fe Kα line has two distinct components—a narrow unresolved component with an equivalent width of ~40 eV and a broad component with a FWHM of ~40,000 km s-1 and an equivalent width of ~120 eV. An absorption feature at ~7.1 keV has also been observed. The energies of the emission and absorption features are consistent with those arising from neutral iron. The broad component is consistent with a Fe Kα emission line expected from a relativistic accretion disk around a Schwarzschild or Kerr black hole. Alternatively, most of the flux in the broad component could also be modeled as reflection emission, which mimics emission line-like features because of the presence of iron K-shell edge at ~7.1 keV; however, the reflection fraction, R ~ 3, is much higher than that inferred from the BeppoSAX observations (R ~ 0.5). The disk inclination angle of ~47°, inferred from the disk-line fits, and the absorption column (NH ~ 1022 cm-2), inferred from the low-energy spectral curvature due to photoelectric absorption, suggest that our line of sight passes through the outer edge of a putative torus and are consistent with those expected for a Seyfert 1.9 galaxy falling within the unification scheme. The strength of the narrow iron Kα emission and the optical depth of the iron K absorption edge suggest their origin in the putative torus with NH ~ 1024 cm-2 in the inner regions and NH ~ 1022 cm-2 in the outer edges. The strength of the broad component of Fe Kα varied by a factor of ~2 between the two XMM-Newton observations taken ~6 months apart, while the narrow component of Fe Kα and the continuum flux did not appear to vary appreciably. There is evidence for a weakening in the strength of the broad iron Kα emission with the flattening of the observed continuum. This can perhaps be explained if the shape of the continuum is coupled with the ionization stage of the reflector.

Quasi-periodic Oscillations and Strongly Comptonized X-Ray Emission from Holmberg IX X-1

We report the discovery of a 200 mHz quasi-periodic oscillation (QPO) in the X-ray emission from a bright ultraluminous X-ray source (ULX), Holmberg IX X-1, using a long XMM-Newton observation. The QPO has a centroid at νQPO = 202.5 mHz, a coherence Q ≡ νQPO/ΔνFWHM ≈ 9.3, and an amplitude (rms) of 6% in the 0.2-10 keV band. This is only the second detection of a QPO from a ULX, after M82 X-1, and provides strong evidence against beaming. The power spectrum is well fitted by a power law with an index of ≈0.7. The total integrated power (rms) is ≈9.4% in the 0.001-1 Hz range. The X-ray spectrum shows clear evidence of a soft X-ray excess component that is well described by a multicolor disk blackbody (kTin ~ 0.3 keV) and a high-energy curvature that can be modeled either by a cutoff power law (Γ ~ 1; Ecutoff = 9 keV) or as a strongly Comptonized continuum in an optically thick (τ ≈ 7.3) and cool (kTe ≈ 3 keV) plasma. Both the presence of the QPO and the shape of the X-ray spectrum strongly suggest that the ULX is not in the high/soft or thermally dominated state. A truncated disk and inner optically thick corona may explain the observed X-ray spectrum and the presence of the QPO.

Revealing the High Energy Emission from the Obscured Seyfert Galaxy MCG -5-23-16 with Suzaku

We report on a 100 ks Suzaku observation of the bright, nearby (z=0.008486) Seyfert 1.9 galaxy MCG -5-23-16. The broad-band (0.4-100 keV) X-ray spectrum allows us to determine the nature of the high energy emission with little ambiguity. The X-ray continuum consists of a cutoff power-law of photon index

XMM-Newton view of the ultraluminous X-ray sources in M51

\Gamma=1.9

Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert galaxies – I. A global view and frequency of occurrence of warm absorbers.

, absorbed through Compton-thin matter of column density

X-Ray Emission from Active Galactic Nuclei with Intermediate-Mass Black Holes

N_{\rm H}=1.6\times10^{22}