scholarly journals The ionic composition of the local absorber towards 3C 273

2020 ◽  
Vol 492 (4) ◽  
pp. 5634-5640
Author(s):  
Itay Gissis ◽  
Uria Peretz ◽  
Ehud Behar
Keyword(s):  
Column Density ◽  
Ionic Composition ◽  
Elemental Abundance ◽  
Ionized Gas ◽  
X Ray ◽  
Line Region ◽  
Collisional Ionization ◽  
X Ray Absorption ◽  
Absorption Features ◽  
Measure Distribution

ABSTRACT Hot ionized gas is observed in the local vicinity of our galaxy through spectral absorption features. The most common hypothesis is that this gas forms a halo surrounding our Milky Way, in collisional ionization equilibrium. In this paper, we investigate the elemental abundance of this hot and ionized local gas. We use a 2.4 Ms stacked X-ray spectrum of the bright blazar 3C 273 and probe the local absorption features. Using ion-by-ion fitting of the X-ray absorption lines, we derive the column density of each ionization species. Based on the column densities, we reconstruct the absorption measure distribution, namely the hydrogenic column density as a function of temperature. We report the elemental abundances of C, N, Ne, and Fe relative to solar O. Previous measurements of local X-ray emission lines in conjunction with the present column densities indicate a scale height of 1–80 kpc and hydrogen number density of 10−4–10−3 cm−3 for the hot ionized gas. Additionally, we detect He-like O lines from the quasar broad line region with velocities of 6400 ± 1500 km s−1.

scholarly journals X-ray Absorption by Ionized Gas in EXOSAT Spectra from the Binary System 4U1700-37/HD153919

1990 ◽  
Vol 115 ◽  
pp. 201-204
Author(s):  
F. Haberl ◽  
T.R. Kallman ◽  
N.E. White
Keyword(s):  
Binary System ◽  
Column Density ◽  
Asymmetric Distribution ◽  
Photoelectric Absorption ◽  
Ionized Gas ◽  
X Ray ◽  
Neutral Gas ◽  
Orbital Phase ◽  
Energy Excess ◽  
X Ray Absorption

AbstractWe observed the 3.41 day eclipsing, massive binary system 4U1700-37/HD153919 with EXOSAT for more than one complete binary period to investigate the spectral variations during the orbital cycle of the neutron star. The spectra show a low energy excess below ~ 3 keV when modelled by a powerlaw spectrum attenuated by photoelectric absorption by neutral gas, suggesting partial ionization of the absorbing gas. The column density derived from spectra above 3 keV shows an asymmetric distribution around orbital phase 0.5 with higher absorption before eclipse ingress. We approximated the with distance to the X-ray source gradually decreasing ionization of the wind by two zones. One of higher ionized wind around the X-ray source for which X-ray opacities of a gas in photoionization equilibrium were used and a zone of neutral gas further away from the X-ray source. We find that our spectra below 3 keV can be well fitted by a powerlaw which is attenuated first by photoelectric absorption of ionized gas and then by neutral gas. Since around phase 0.5 the major contribution of the wind column density along the line of sight arises from the ionized part we found that the total column density can be higher up to a factor of about 4 taking ionization into account.

scholarly journals Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton

2002 ◽  
Vol 386 (3) ◽  
pp. 910-915 ◽  
Author(s):  
A. N. Parmar ◽  
T. Oosterbroek ◽  
L. Boirin ◽  
D. Lumb
Keyword(s):  
X Ray ◽  
Low Mass ◽  
X Ray Absorption ◽  
Absorption Features

scholarly journals Discovery of complex narrow X–ray absorption features from the low-mass X–ray binary GX 13+1 with XMM-Newton

2002 ◽  
Vol 385 (3) ◽  
pp. 940-946 ◽  
Author(s):  
L. Sidoli ◽  
A. N. Parmar ◽  
T. Oosterbroek ◽  
D. Lumb
Keyword(s):  
X Ray ◽  
Low Mass ◽  
X Ray Absorption ◽  
Absorption Features

scholarly journals Synthesis and characterisation of HIP Ca0.80Ce0.20ZrTi1.60Cr0.40O7 zirconolite and observations of the ceramic–canister interface

MRS Advances ◽  
2021 ◽  
Author(s):  
Lewis R. Blackburn ◽  
Max R. Cole ◽  
Laura J. Gardner ◽  
Daniel J. Bailey ◽  
Merve Kuman ◽  
...  
Keyword(s):  
Oxidation State ◽  
Hot Isostatic Pressing ◽  
Nominal Composition ◽  
Phase Assemblage ◽  
X Ray ◽  
Bulk Ceramic ◽  
Average Oxidation State ◽  
Temperature And Pressure ◽  
X Ray Absorption ◽  
Absorption Features

Abstract A sample of zirconolite with nominal composition Ca0.80Ce0.20ZrTi1.60Cr0.40O7 was processed via Hot Isostatic Pressing (HIP), with a dwell temperature and pressure of 1320 °C/100 MPa maintained for 4 h. The produced wasteform was characterised by powder XRD, SEM–EDS, Ce L3 and Cr K-edge XANES. A significant portion of the Ce inventory did not fully partition within the zirconolite phase, instead remaining as CeO2 within the microstructure. Inspection of the stainless steel–ceramic interface detailed the presence of an interaction region dominated by a Cr-rich oxide layer. No significant Cr or Fe migration was observed, although a greater concentration of perovskite was observed at the periphery, relative to the bulk ceramic matrix. The X-ray absorption features of Cr remained analogous with Cr3+ accommodation within TiO6 octahedra in the zirconolite matrix. The absorption edge of Ce was comprised of contributions from zirconolite-2M and unincorporated CeO2, with an average oxidation state of Ce3.9+. As zirconolite-2M accounted for > 92 wt% of the overall phase assemblage, it is clear that the dominant oxidation state of Ce in this phase was Ce4+. Graphic abstract

scholarly journals X-ray spectral and eclipsing model of the clumpy obscurer in active galactic nuclei

2019 ◽  
Vol 629 ◽  
pp. A16 ◽  
Author(s):  
Johannes Buchner ◽  
Murray Brightman ◽  
Kirpal Nandra ◽  
Robert Nikutta ◽  
Franz E. Bauer
Keyword(s):  
Active Galactic Nuclei ◽  
Column Density ◽  
Galactic Nuclei ◽  
Line Of Sight ◽  
Broad Line ◽  
X Ray ◽  
Line Region ◽  
Self Consistent ◽  
Multi Wavelength ◽  
Table Model

We present a unification model for a clumpy obscurer in active galactic nuclei (AGN) and investigate the properties of the resulting X-ray spectrum. Our model is constructed to reproduce the column density distribution of the AGN population and cloud eclipse events in terms of their angular sizes and frequency. We developed and released a generalised Monte Carlo X-ray radiative transfer code, XARS, to compute X-ray spectra of obscurer models. The geometry results in strong Compton scattering, causing soft photons to escape also along Compton-thick sight lines. This makes our model spectra very similar to our TORUS previous model. However, only if we introduce an additional Compton-thick reflector near the corona, we achieve good fits to NuSTAR spectra. This additional component in our model can be interpreted as part of the dust-free broad-line region, an inner wall or rim, or a warped disk. It cannot be attributed to a simple disk because the reflector must simultaneously block the line of sight to the corona and reflect its radiation. We release our model as an Xspec table model and present corresponding CLUMPY infrared spectra, paving the way for self-consistent multi-wavelength analyses.

scholarly journals Electron-Ion Recombination Measurements Motivated by AGN X-Ray Absorption Features: Fe xiv Forming Fe xiii

2006 ◽  
Vol 641 (2) ◽  
pp. L157-L160 ◽  
Author(s):  
E. W. Schmidt ◽  
S. Schippers ◽  
A. Müller ◽  
M. Lestinsky ◽  
F. Sprenger ◽  
...  
Keyword(s):  
X Ray ◽  
Ion Recombination ◽  
X Ray Absorption ◽  
Absorption Features

scholarly journals Neutral Clouds Within the Local X-ray Plasma

1997 ◽  
Vol 166 ◽  
pp. 165-168
Author(s):  
Jürgen Kerp ◽  
Jochen Pietz
Keyword(s):  
Optical Absorption ◽  
Energy Band ◽  
Atomic Hydrogen ◽  
Low Velocity ◽  
X Ray ◽  
Neutral Clouds ◽  
X Ray Absorption ◽  
Local Cloud ◽  
Absorption Features ◽  
Distance Limit

AbstractWe present new results based on the analysis of ROSAT PSPC observations towards nearby neutral clouds. These clouds are detectable as deep soft X-ray absorption features within the ¼ keV energy band. Towards one of these clouds, optical absorption line measurements determine an upper distance limit of D ≤ 60 pc. The presented data suggest that this filament is only a part of a much more extended local–cloud structure. Here we demonstrate that we most probably detected a local neutral atomic hydrogen “wall” in the direction of a low–velocity arc (Pietz 1994).

scholarly journals The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

2020 ◽  
Vol 498 (1) ◽  
pp. 574-598 ◽  
Author(s):  
Nastasha A Wijers ◽  
Joop Schaye ◽  
Benjamin D Oppenheimer
Keyword(s):  
Column Density ◽  
Extreme Ultraviolet ◽  
Gas Well ◽  
X Ray ◽  
Filling Phase ◽  
Circumgalactic Medium ◽  
Halo Masses ◽  
Collisional Ionization ◽  
Far Ultraviolet ◽  
Halo Gas

ABSTRACT We use the EAGLE (Evolution and Assembly of GaLaxies and their Environments) cosmological simulation to study the distribution of baryons, and far-ultraviolet (O vi), extreme-ultraviolet (Ne viii), and X-ray (O vii, O viii, Ne ix, and Fe xvii) line absorbers, around galaxies and haloes of mass $\,{M}_{\rm {200c}}= 10^{11}$–$10^{14.5} \, \rm {M}_{\odot}$ at redshift 0.1. EAGLE predicts that the circumgalactic medium (CGM) contains more metals than the interstellar medium across halo masses. The ions we study here trace the warm-hot, volume-filling phase of the CGM, but are biased towards temperatures corresponding to the collisional ionization peak for each ion, and towards high metallicities. Gas well within the virial radius is mostly collisionally ionized, but around and beyond this radius, and for O vi, photoionization becomes significant. When presenting observables, we work with column densities, but quantify their relation with equivalent widths by analysing virtual spectra. Virial-temperature collisional ionization equilibrium ion fractions are good predictors of column density trends with halo mass, but underestimate the diversity of ions in haloes. Halo gas dominates the highest column density absorption for X-ray lines, but lower density gas contributes to strong UV absorption lines from O vi and Ne viii. Of the O vii (O viii) absorbers detectable in an Athena X-IFU blind survey, we find that 41 (56) per cent arise from haloes with $\,{M}_{\rm {200c}}= 10^{12.0}{-}10^{13.5} \, \rm {M}_{\odot}$. We predict that the X-IFU will detect O vii (O viii) in 77 (46) per cent of the sightlines passing $\,{M}_{\star }= 10^{10.5}{-}10^{11.0} \, \rm {M}_{\odot}$ galaxies within $100 \, \rm {pkpc}$ (59 (82) per cent for $\,{M}_{\star }\gt 10^{11.0} \, \rm {M}_{\odot}$). Hence, the X-IFU will probe covering fractions comparable to those detected with the Cosmic Origins Spectrograph for O vi.

scholarly journals Incoherent fast variability of X-ray obscurers

2020 ◽  
Vol 634 ◽  
pp. A65 ◽  
Author(s):  
B. De Marco ◽  
T. P. Adhikari ◽  
G. Ponti ◽  
S. Bianchi ◽  
G. A. Kriss ◽  
...  
Keyword(s):  
Column Density ◽  
Timing Analysis ◽  
Seyfert Galaxies ◽  
Fast Response ◽  
Broad Line ◽  
X Ray ◽  
Line Region ◽  
Timing Properties ◽  
The Impact ◽  
High Column

Context. Obscuration events caused by outflowing clumps or streams of high column density and low ionised gas, shown to absorb the X-ray continuum heavily, have been witnessed across a number of Seyfert galaxies. Aims. We report on the X-ray spectral-timing analysis of the December 2016 obscuration event in NGC 3783, which was aimed at probing variability of the X-ray obscurer on the shortest possible timescales. The main goals of this study are to obtain independent constraints on the density and, ultimately on the distance of the obscuring gas, as well as to characterise the impact of variable obscuration on the observed X-ray spectral-timing characteristics of Seyfert galaxies. Methods. We carried out a comparative analysis of NGC 3783 during unobscured (using archival 2000–2001 XMM-Newton data) and obscured states (using XMM-Newton and NuSTAR data from the 2016 observational campaign). The analysed timescales range between ten hours and about one hour. This study was then generalised to discuss the signatures of variable obscuration in the X-ray spectral-timing characteristics of Seyfert galaxies as a function of the physical properties of the obscuring gas. Results. The X-ray obscurer in NGC 3783 is found to vary on timescales between about one hour to ten hours. This variability is incoherent with respect to the variations of the X-ray continuum. A fast response (on timescales shorter than about 1.5 ks) of the ionisation state of the obscuring gas to the short timescale variability of the primary X-ray continuum provides a satisfactory interpretation of all the observed X-ray spectral-timing properties. This study enabled us to put independent constraints on the density and location of the obscuring gas. We found the gas to have a density of ne >  7.1 × 107 cm−3, which is consistent with a location in the broad line region.

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