Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userXMM-Newton and NuSTAR joint observations of Mrk 915: a deep look into the X-ray properties
93
0
0.0
(
0
)
Authors
L. Ballo
Ask ChatGPT about the research
No Arabic abstract
We report on the X-ray monitoring programme (covering slightly more than 11 days) carried out jointly by XMM-Newton and NuSTAR on the intermediate Seyfert galaxy Mrk 915. The light curves extracted in different energy ranges show a variation in intensity but not a significant change in spectral shape. The X-ray spectra reveal the presence of a two-phase warm absorber: a fully covering mildly ionized structure [log xi/(erg cm/s)~2.3, NH~1.3x10^21 cm-2] and a partial covering (~90 per cent) lower ionized one [log xi/(erg cm/s)~0.6, NH~2x10^22 cm-2]. A reflection component from distant matter is also present. Finally, a high-column density (NH~1.5x10^23 cm-2) distribution of neutral matter covering a small fraction of the central region is observed, almost constant, in all observations. Main driver of the variations observed between the datasets is a decrease in the intrinsic emission by a factor of ~1.5. Slight variations in the partial covering ionized absorber are detected, while the data are consistent with no variation of the total covering absorber. The most likely interpretation of the present data locates this complex absorber closer to the central source than the narrow line region, possibly in the broad line region, in the innermost part of the torus, or in between. The neutral obscurer may either be part of this same stratified structure or associated with the walls of the torus, grazed by (and partially intercepting) the line of sight.
rate research
Read More
We present simultaneous XMM-Newton and NuSTAR observations spanning 3-78 keV of the nearest radio galaxy, Centaurus A (Cen A). The accretion geometry around the central engine in Cen A is still debated, and we investigate possible configurations using detailed X-ray spectral modeling. NuSTAR imaged the central region of Cen A with sub-arcminute resolution at X-ray energies above 10 keV for the first time, but finds no evidence for an extended source or other off-nuclear point-sources. The XMM-Newton and NuSTAR spectra agree well and can be described with an absorbed power-law with a photon index {Gamma} = 1.815 +/- 0.005 and a fluorescent Fe K{alpha} line in good agreement with literature values. The spectrum does not require a high-energy exponential rollover, with a constraint of E_fold > 1 MeV. A thermal Comptonization continuum describes the data well, with parameters that agree with values measured by INTEGRAL, in particular an electron temperature kTe between ~100-300 keV, seed photon input temperatures between 5-50 eV. We do not find evidence for reflection or a broad iron line and put stringent upper limits of R < 0.01 on the reflection fraction and accretion disk illumination. We use archival Chandra data to estimate the contribution from diffuse emission, extra-nuclear point-sources, and the outer X-ray jet to the observed NuSTAR and XMM-Newton X-ray spectra and find the contribution to be negligible. We discuss different scenarios for the physical origin of the observed hard X-ray spectrum, and conclude that the inner disk is replaced by an advection-dominated accretion flow or that the X-rays are dominated by synchrotron self-Compton emission from the inner regions of the radio jet or a combination thereof.
We report the results of an XMM-Newton and NuSTAR coordinated observation of the Supergiant Fast X-ray Transient (SFXT) IGRJ11215-5952, performed on February 14, 2016, during the expected peak of its brief outburst, which repeats every about 165 days. Timing and spectral analysis were performed simultaneously in the energy band 0.4-78 keV. A spin period of 187.0 +/- 0.4 s was measured, consistent with previous observations performed in 2007. The X-ray intensity shows a large variability (more than one order of magnitude) on timescales longer than the spin period, with several luminous X-ray flares which repeat every 2-2.5 ks, some of which simultaneously observed by both satellites. The broad-band (0.4-78 keV) time-averaged spectrum was well deconvolved with a double-component model (a blackbody plus a power-law with a high energy cutoff) together with a weak iron line in emission at 6.4 keV (equivalent width, EW, of 40+/-10 eV). Alternatively, a partial covering model also resulted in an adequate description of the data. The source time-averaged X-ray luminosity was 1E36 erg/s (0.1-100 keV; assuming 7 kpc). We discuss the results of these observations in the framework of the different models proposed to explain SFXTs, supporting a quasi-spherical settling accretion regime, although alternative possibilities (e.g. centrifugal barrier) cannot be ruled out.
(Abridged) Soft and hard X-ray excesses, compared to the continuum power-law shape between ~2-10 keV, are common features observed in the spectra of active galactic nuclei (AGN) and are associated with the accretion disc-corona system around the supermassive black hole. However, the dominant process at work is still highly debated and has been proposed to be either relativistic reflection or Comptonisation. We aim to characterise the main X-ray spectral physical components from the bright bare Broad Line Seyfert 1 AGN Mrk 110, and the physical process(es) at work in its disc-corona system viewed almost face-on. We perform the X-ray broad-band spectral analysis thanks to two simultaneous XMM-Newton and NuSTAR observations performed on November 16-17 2019 and April 5-6 2020, we also use for the spectral analysis above 3 keV the deep NuSTAR observation obtained in January 2017. The broad-band X-ray spectra of Mrk 110 are characterised by the presence of a prominent and absorption-free smooth soft X-ray excess, moderately broad OVII and FeKalpha emission lines and a lack of a strong Compton hump. The continuum above ~3keV is very similar at both epochs, while some variability (stronger when brighter) is present for the soft X-ray excess. A combination of soft and hard Comptonisation by a warm and hot corona, respectively, plus mildly relativistic disc reflection reproduce the broadband X-ray continuum very well. The inferred warm corona temperature, kT_warm~0.3 keV, is similar to the values found in other sub-Eddington AGN, whereas the hot corona temperature, kT_hot~21-31 keV (depending mainly on the assumed hot corona geometry), is found to be in the lower range of the values measured in AGN.
We present a high-quality hard X-ray spectrum of the ultraluminous X-ray source (ULX) NGC 5643 X-1 measured with NuSTAR in May-June 2014. We have obtained this spectrum by carefully separating the signals from the ULX and from the active nucleus of its host galaxy NGC 5643 located 0.8 arcmin away. Together with long XMM-Newton observations performed in July 2009 and August 2014, the NuSTAR data confidently reveal a high-energy cutoff in the spectrum of NGC 5643 X-1 above ~10 keV, which is a characteristic signature of ULXs. The NuSTAR and XMM-Newton data are consistent with the source having a constant luminosity ~1.5E40 erg/s (0.2-12 keV) in all but the latest observation (August 2014) when it brightened to ~3E40 erg/s. This increase is associated with the dominant, hard spectral component (presumably collimated emission from the inner regions of a supercritical accretion disc), while an additional, soft component (with a temperature ~0.3 keV if described by multicolor disk emission), possibly associated with a massive wind outflowing from the disk, is also evident in the spectrum but does not exhibit significant variability.
We present the first broadband 0.3-25.0 kev X-ray observations of the bright ultraluminous X-ray source (ULX) Holmberg II X-1, performed by NuSTAR, XMM-Newton and Suzaku in September 2013. The NuSTAR data provide the first observations of Holmberg II X-1 above 10 keV, and reveal a very steep high-energy spectrum, similar to other ULXs observed by NuSTAR to date. These observations further demonstrate that ULXs exhibit spectral states that are not typically seen in Galactic black hole binaries. Comparison with other sources implies that Holmberg II X-1 accretes at a high fraction of its Eddington accretion rate, and possibly exceeds it. The soft X-ray spectrum (E<10 keV) appears to be dominated by two blackbody-like emission components, the hotter of which may be associated with an accretion disk. However, all simple disk models under-predict the NuSTAR data above ~10 keV and require an additional emission component at the highest energies probed, implying the NuSTAR data does not fall away with a Wien spectrum. We investigate physical origins for such an additional high-energy emission component, and favor a scenario in which the excess arises from Compton scattering in a hot corona of electrons with some properties similar to the very-high state seen in Galactic binaries. The observed broadband 0.3-25.0 keV luminosity inferred from these epochs is Lx = (8.1+/-0.1)e39 erg/s, typical for Holmberg II X-1, with the majority of the flux (~90%) emitted below 10 keV.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
