99 research outputs found
X-ray and Sunyaev-Zeldovich properties of the WHIM
We use numerical simulations to predict the soft X-ray ([0.4-0.6] keV) and
Sunyaev-Zeldovich signal (at 150 GHz) from the large scale structure in the
Universe and then compute 2-point statistics to study the spatial distribution
and time evolution of the signals. The average X-ray signal predicted for the
WHIM is in good agreement with observational constraints that set it at about
10% of the total Diffuse X-ray Background. The characteristic angle computed
with the Autocorrelation Function is of the order of some arcminutes and
becomes smaller at higher redshift. The power spectrum peak of the SZ due to
the WHIM is at l~10000 and has amplitude of ~0.2 muK^2, about one order of
magnitude below the signal measured with telescopes like Planck, ACT, and SPT.
Even if the high-redshift WHIM signal is too weak to be detected using X-rays
only, the small-scale correlation between X-ray and SZ maps is dominated by the
high-redshift WHIM. This makes the analysis of the SZ signal in support of
X-rays a promising tool to study the early time WHIM.Comment: 13 Pages, 10 Figures, Accepted for Publication on Ap
Study of the Intracluster and Intergalactic Medium in the Sculptor Supercluster with Suzaku
We studied the high temperature plasma in the direction of the Sculptor
supercluster at z=0.108 with Suzaku. Suzaku carried out four observations in
the supercluster: namely, A2811, A2811 offset, A2804, A2801 regions in 2005
Nov.--Dec., including the regions beyond the virial radii of these clusters.
The study needed precise background estimation because the measured intensity
of the redshifted lines, especially those from oxygen, were strongly affected
by the the Galactic emission. The spectra taken in the regions outside of the
virial radii of the member clusters were used as the background which included
both the Galactic and Cosmic X-ray Background (CXB) components. We also used
the background data which were taken near the Sculptor supercluster.
Temperature and metal abundance profiles were determined to the virial radii of
the member clusters, and then we searched for the oxygen line emission in the
region outside of the virial radii of the clusters. As a result, the
temperature of the clusters decreased toward the virial radii, and the spectral
fits for the filament region did not require extra component other than the
Galactic and CXB components. We constrained the intensities of O VII and O VIII
lines to be less than 8.1 and 5.1 photons cm^-2 s^-1 arcmin^-2, respectively,
as 2-sigma upper limits. The intensity of O VII indicates n_H < 1.6e-5 cm^-3
(Z/0.1 Z_solar)^-1/2 (L/25 Mpc)^-1/2, which corresponds to an over density,
delta < 60 (Z/0.1 Z_solar)^-1/2 (L/25 Mpc)^-1/2.Comment: 11 pages, 8 figures, accepted for publication in PAS
Search for X-Ray Emission Associated with the Shapley Supercluster with Suzaku
Suzaku performed observations of 3 regions in and around the Shapley
supercluster: a region located between A3558 and A3556, at ~0.9 times the
virial radii of both clusters, and two other regions at 1{\deg}and 4{\deg}away
from the first pointing. The 4{\deg}-offset observation was used to evaluate
the Galactic foreground emission. We did not detect significant redshifted
Oxygen emission lines (O VII and O VIII) in the spectra of all three pointings,
after subtracting the contribution of foreground and background emission. An
upper limit for the redshifted O VIII Ka line intensity of the warm-hot
intergalactic medium (WHIM) is 1.5 \times 10^-7 photons s^-1 cm^-2 arcmin^-2,
which corresponds to an overdensity of ~380 (Z/0.1 Z_solar)^{-1/2} (L/3
Mpc)^{-1/2}, assuming T=3\times10^6 K. We found excess continuum emission in
the 1{\deg}-offset and on-filament regions, represented by thermal models with
kT ~1 keV and ~2 keV, respectively. The redshifts of both 0 and that of the
supercluster (0.048) are consistent with the observed spectra. The ~1 keV
emission can be also fitted with Ne-rich Galactic (zero redshift) thin thermal
emission. Radial intensity profile of 2 keV component suggests contribution
from A3558 and A3556, but with significant steepening of the intensity slope in
the outer region of A3558. Finally, we summarized the previous Suzaku search
for the WHIM and discussed the feasibility of constraining the WHIM. An
overdensity of < 400 can be detectable using O VII and O VIII emission lines in
a range of 1.4\times10^6 K < T < 5\times10^6 K or a continuum emission in a
relatively high temperature range T > 5\times10^6 K with the Suzaku XIS. The
non detection with Suzaku suggests that typical line-of-sight average
overdensity is < 400
Super-virial temperature or Neon overabundance?: Suzaku observations of the Milky Way circumgalactic Medium
We analyzed Suzaku and Chandra observations of the soft diffuse X-ray
background toward four sightlines with the goal of characterizing the X-ray
emission from the Milky Way circumgalactic medium (CGM). We identified two
thermal components of the CGM, one at a uniform temperature of and the other at temperatures ranging between . The uniform lower temperature component is consistent with the
Galaxy's virial temperature (). The temperatures of the hotter
components are similar to that recently discovered (; Das
et al.) in the sightline to blazar 1ES1553+113, passing close to the Fermi
bubble. Alternatively, the spectra can be described by just one
lower-temperature component with super-solar Neon abundance, once again similar
to that found in the 1ES1553+113 sightline. The additional hot component or the
overabundance of Ne is required at a significance of , but we cannot
distinguish between the two possibilities. These results show that the
super-virial temperature gas or an enhanced Ne abundance in the warm-hot gas in
the CGM is widespread, and these are not necessarily related to the Fermi
bubble.Comment: Accepted for Publication in Ap
Invited Article: First flight in space of a wide-field-of-view soft x-ray imager using lobster-eye optics: Instrument description and initial flight results
We describe the development, launch into space, and initial results from a prototype wide field-of-view soft X-ray imager that employs lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The sheath transport observer for the redistribution of mass is the first instrument using this type of optics launched into space and provides proof-of-concept for future flight instruments capable of imaging structures such as the terrestrial cusp, the entire dayside magnetosheath from outside the magnetosphere, comets, the Moon, and the solar wind interaction with planetary bodies like Venus and Mars [Kuntz et al., Astrophys. J. (in press)]
A High Spectral Resolution Study of the Soft X-ray Background with the X-ray Quantum Calorimeter
We present here a combined analysis of four high spectral resolution
observations of the Diffuse X-ray Background (DXRB), made using the University
of Wisconsin-Madison/Goddard Space Flight Center X-ray Quantum Calorimeter
(XQC) sounding rocket payload. The observed spectra support the existence of a
keV Local Hot Bubble and a keV Hot Halo, with discrepancies
between repeated observations compatible with expected contributions of
time-variable emission from Solar Wind Charge Exchange (SWCX). An additional
component of keV emission observed only at low galactic latitudes can
be consistently explained by unresolved dM stars.Comment: 21 pages, 6 figures, accepted for publication in Ap
Invited Article: First Flight in Space of a Wide-Field-of-View Soft X-Ray Imager Using Lobster-Eye Optics: Instrument Description and Initial Flight Results
We describe the development, launch into space, and initial results from a prototype wide eld-of-view (FOV) soft X-ray imager that employs Lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The Sheath Transport Observer for the Redistribution of Mass (STORM) is the rst instrument using this type of optics launched into space and provides proof-of-concept for future ight instruments capable of imaging structures such as the terrestrial cusp, the entire dayside magnetosheath from outside the magnetosphere, comets, the moon, and the solar wind interaction with planetary bodies like Venus and Mars
LEM All-Sky Survey: Soft X-ray Sky at Microcalorimeter Resolution
The Line Emission Mapper (LEM) is an X-ray Probe with with spectral
resolution ~2 eV FWHM from 0.2 to 2.5 keV and effective area >2,500 cm at 1
keV, covering a 33 arcmin diameter Field of View with 15 arcsec angular
resolution, capable of performing efficient scanning observations of very large
sky areas and enabling the first high spectral resolution survey of the full
sky. The LEM-All-Sky Survey (LASS) is expected to follow the success of
previous all sky surveys such as ROSAT and eROSITA, adding a third dimension
provided by the high resolution microcalorimeter spectrometer, with each 15
arcsec pixel of the survey including a full 1-2 eV resolution energy spectrum
that can be integrated over any area of the sky to provide statistical
accuracy. Like its predecessors, LASS will provide both a long-lasting legacy
and open the door to the unknown, enabling new discoveries and delivering the
baseline for unique GO studies. No other current or planned mission has the
combination of microcalorimeter energy resolution and large grasp to cover the
whole sky while maintaining good angular resolution and imaging capabilities.
LASS will be able to probe the physical conditions of the hot phases of the
Milky Way at multiple scales, from emission in the Solar system due to Solar
Wind Charge eXchange, to the interstellar and circumgalactic media, including
the North Polar Spur and the Fermi/eROSITA bubbles. It will measure velocities
of gas in the inner part of the Galaxy and extract the emissivity of the Local
Hot Bubble. By maintaining the original angular resolution, LASS will also be
able to study classes of point sources through stacking. For classes with
~ objects, it will provide the equivalent of 1 Ms of high spectral
resolution data. We describe the technical specifications of LASS and highlight
the main scientific objectives that will be addressed. (Abridged)Comment: White Paper in support of a mission concept to be submitted for the
2023 NASA Astrophysics Probes opportunity. This White Paper will be updated
when required. 30 pages, 25 figure
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