46 research outputs found
Searching for the warm-hot intergalactic medium using XMM-Newton high-resolution X-ray spectra
The problem of missing baryons in the local universe remains an open
question. One propose alternative is that at low redshift missing baryons are
in the form of the Warm Hot Intergalactic Medium (WHIM). In order to test this
idea, we present a detailed analysis of X-ray high-resolution spectra of six
extragalactic sources, Mrk 421, 1ES 1028+511, 1ES 1553+113, H2356-309, PKS
0558-504 and PG 1116+215, obtained with the XMM-Newton Reflection Grating
Spectrometer to search for signals of WHIM and/or circumgalactic medium (CGM)
X-ray absorbing gas. We fit the X-ray absorption with the IONeq model, allowing
us to take into account the presence of X-ray spectral features due to the
multiphase component of the local ISM. An additional IONeq component is
included to model the WHIM absorption, instead of the traditional Gaussian
absorption line modeling. We found no statistical improvement in the fits when
including such component in any of the sources, concluding that we can safely
reject a successful detection of WHIM absorbers towards these lines of sights.
Our simulation shows that the presence of the multiphase ISM absorption
features prevents detection of low-redshift WHIM absorption features in the 17
A spectral region for moderate exposures using high-resolution spectra.Comment: 12 pages, 7 figure
Chandra high-resolution spectra of 4U 1630-47: the disappearance of the wind
We present the analysis of six Chandra X-ray high-resolution observations of the black hole low-mass X-ray binary 4U 1630-47 taken during its 2012–2013 outburst. Fe XXVI K α, K β, Fe XXV K α, K β, and Ca XX K α blueshifted absorption lines were identified in the first four observations, which correspond to soft accretion states. The remaining observations, associated to intermediate and possibly hard accretion states, do not show significant absorption features down to equivalent width of 1 eV for both Fe XXVI and Fe XXV. We inferred wind launching radii between 1.2 − 2.0 (1012 cm/n) × 1011 cm and column densities N(H) > 1023 cm−2. In the first four observations, we found that thermal pressure is likely to be the dominant launching mechanism for the wind, although such conclusions depend on the assumed density. We used the spectral energy distributions obtained from our continuum modelling to compute thermal stability curves for all observations using the XSTAR photoionization code. We found that the absence of lines in the transitional state cannot be attributed to an evolution of the plasma caused by thermal instabilities derived from the change in the continuum spectrum. In contrast, the disappearance of the wind could indicate an acceleration of the flow or that the plasma has been exhausted during the soft state
Simultaneous detection of an intrinsic absorber and a compact jet emission in the X-ray binary IGR J17091-3624 during a hard accretion state
We present a detailed analysis of three XMM-Newton observations of the black
hole low-mass X-ray binary IGR~J17091-3624 taken during its 2016 outburst.
Radio observations obtained with the Australia Telescope Compact Array (ATCA)
indicate the presence of a compact jet during all observations. From the best
X-ray data fit results we concluded that the observations were taken during a
transition from a hard accretion state to a hard-intermediate accretion state.
For Observations 1 and 2 a local absorber can be identified in the EPIC-pn
spectra but not in the RGS spectra, preventing us from distinguishing between
absorption local to the source and that from the hot ISM component. For
Observation 3, on the other hand, we have identified an intrinsic ionized
static absorber in both EPIC-pn and RGS spectra. The absorber, observed
simultaneously with a compact jet emission, is characterized by an ionization
parameter of 1.96< log({\xi}) <2.05 and traced mainly by Ne X, Mg XII, Si XIII
and Fe XVIII.Comment: 13 pages, 10 figure
A Comprehensive X-ray Absorption Model for Atomic Oxygen
An analytical formula is developed to represent accurately the
photoabsorption cross section of O I for all energies of interest in X-ray
spectral modeling. In the vicinity of the Kedge, a Rydberg series expression is
used to fit R-matrix results, including important orbital relaxation effects,
that accurately predict the absorption oscillator strengths below threshold and
merge consistently and continuously to the above-threshold cross section.
Further minor adjustments are made to the threshold energies in order to
reliably align the atomic Rydberg resonances after consideration of both
experimental and observed line positions. At energies far below or above the
K-edge region, the formulation is based on both outer- and inner-shell direct
photoionization, including significant shake-up and shake-off processes that
result in photoionization-excitation and double photoionization contributions
to the total cross section. The ultimate purpose for developing a definitive
model for oxygen absorption is to resolve standing discrepancies between the
astronomically observed and laboratory measured line positions, and between the
inferred atomic and molecular oxygen abundances in the interstellar medium from
XSTAR and SPEX spectral models
Erratum: "Photoionization Modeling of Oxygen K Absorption in the Interstellar Medium, the Chandra Grating Spectra of XTE J1817-330" (2013, Apj, 768, 60)
In the published version of this paper, there are some minor inaccuracies in the absorption-line wavelengths listed in Table 4 as a result of a faulty reduction procedure of the Obs6615 spectrum. The shifts have been detected in a comparison with the wavelengths listed for this spectrum in the Chandra Transmission Grating Catalog and Archive (TGCat8). They are due to incorrect centroid positions of the zero-order image in both reductions as determined by the tgdetect utility which, when disentangled, yield the improved line positions of the amended Table 4 given below. It must also be pointed out that other quantitative findings of the original paper: 1. Table 5, p. 9: the column density (NH), ionization parameter, oxygen abundance of the warmabs model and the normalization and photon index of the power-law model; 2. Table 6, p. 9: the hydrogen column density of the warmabs fit; 3. Table 7, p. 9: the present oxygen equivalent widths of XTE J1817-330; and 4. Table 8, p. 10: the present oxygen column densities of XTE J1817-330 derived from both the curve of growth and warmabs model fit have been revised in the new light and are, within the estimated uncertainty ranges, in good accord with the new rendering
X-ray analysis of JWST's first galaxy cluster lens SMACS J0723.3-7327
SMACS~J0723.3-7327 is the first galaxy cluster lens observed by JWST. Based
on the ERO data from JWST, several groups have reported the results on strong
lensing analysis and mass distribution of this cluster. However, limited by the
angular coverage of the JWST data, the strong lensing models only cover the
central region. X-ray analysis on the hot ICM is necessary to obtain a more
complete constraint on the mass distribution in this very massive cluster. In
this work, we aim to perform a comprehensive X-ray analysis of J0723 to obtain
accurate ICM hydrostatic mass measurements, using the X-ray data from
SRG/eROSITA and Chandra X-ray observatories. By comparing the hydrostatic mass
profile with the strong lensing model, we aim to provide the most reliable
constraint on the distribution of mass up to R500. Thanks to the eROSITA
all-sky survey and Chandra data, which provide high S/N and high angular
resolution respectively, we are able to constrain the ICM gas density profile
and temperature profile with good accuracy both in the core and to the
outskirts. With the density and temperature profiles, we compute the
hydrostatic mass profile, which is then projected along the line of sight to
compare with the mass distribution obtained from the recent strong lensing
analysis based on JWST data. We also deproject the strong lensing mass
distribution using the hydrostatic mass profile we obtained in this work. The
X-ray results obtained from eROSITA and Chandra agree very well with each
other. The hydrostatic mass profiles we measured in this work, both projected
and deprojected, are in good agreement with recent strong lensing results based
on JWST data, at all radii. We also find that the radial acceleration relation
in J0723 is inconsistent with the RAR for spiral galaxies, implying that the
latter is not a universal property of gravity across all mass scales.Comment: Accepted for publication in A&