41 research outputs found
SRG/eROSITA X-ray shadowing study of giant molecular clouds
SRG/eROSITA is situated in a halo orbit around L2 where the highly variable
solar wind charge exchange (SWCX) emission from Earth's magnetosheath is
expected to be negligible. The soft X-ray foreground emissions from the local
hot bubble (LHB) and the remaining heliospheric SWCX emissions could be studied
in unprecedented detail with eROSITA All-Sky Survey (eRASS) data in a 6-month
cadence and better spectral resolution than ROSAT. We aim to use eRASS data of
the sight lines towards three giant molecular clouds away from the Galactic
plane to isolate and study the soft X-ray diffuse foreground emission. These
X-ray shadows will serve as calibration baselines for the future
three-dimensional structural study of the LHB. We conducted spectral analysis
on the diffuse X-ray spectra of these clouds from the first four eRASSs to
estimate and separate the heliospheric SWCX contribution from the LHB emission.
We find the density of the LHB to be independent of the sight line with cm, but not the temperature. We report a lower
temperature of keV towards ChamaeleonII &
III (ChaII & III) than Ophiuchus (Oph) and Corona Australis (CrA), in which
we measured and keV, respectively. We measured
the emission measure of the LHB to be cmpc at
medium Galactic latitudes (). A monotonic increase in the
SWCX contribution has been observed since the start of 2020, coincidental with
the beginning of solar cycle 25. For Oph, SWCX has dominated the LHB in the
-keV band intensity since eRASS2. We observed lower SWCX
contributions in ChaII & III and CrA, consistent with the expected
decreasing solar wind ion density at high heliographic latitudes.Comment: 22 pages, 15 figures. Accepted for publication in A&
SRG/eROSITA and XMM-Newton observations of Vela Jr
The Vela supernova remnant complex is a region containing at least three
supernova remnants: Vela, Puppis A, and Vela Jr. With the launch of the
spectro-imaging X-ray telescope eROSITA on board the Spectrum Roentgen Gamma
(SRG) mission, it became possible to observe the one degree wide Vela Jr in its
entirety. Although several previous pointed Chandra and XMM-Newton observations
are available, it is only the second time after the ROSAT all-sky survey that
the whole remnant was observed in X-rays with homogeneous sensitivity. Vela Jr
is one of the few remnants emitting in the TeV band, making it an important
object in shock acceleration studies. However, the age and distance
determination using X-ray emission is largely hampered by the presence of the
Vela SNR along the same line. With the eROSITA data set our aim is to
characterize the emission of Vela Jr and distinguish it from Vela emission, and
also to characterize the spectral emission of the inner remnant. We processed
the eROSITA data dividing the whole remnant into seven different regions. In
addition, images of the whole remnant were employed to pinpoint the position of
the geometric center and constrain the proper motion of the CCO. We also
employed archival XMM-Newton pointed observations of the NW rim to determine
the cutoff energy of the electrons and the expansion velocity. We find the
magnetic field can vary between 2 G and 16 G in the NW rim. We also
find that the remnant spectrum is uniformly featureless in most regions, except
for two inner regions where an extra thermal model component improves the fit.
We obtain new coordinates for the geometric remnant center, resulting in a
separation of only 35.2 15.8" from the position of the CCO. As a result,
we reinforce the association between the CCO and a proposed faint optical/IR
counterpart.Comment: Accepted for publication in A&
Spectroscopic Signatures of the Superorbital Period in the Neutron Star Binary LMC X-4
We present the first high-resolution X-ray study of emission line variability
with superorbital phase in the neutron star binary LMC X-4. Our analysis
provides new evidence from X-ray spectroscopy confirming accretion disk
precession as the origin of the superorbital period. The spectra, obtained with
the Chandra High-Energy Transmission Grating Spectrometer (HETGS) and the
XMM-Newton Reflection Grating Spectrometer (RGS), contain a number of emission
features, including lines from hydrogen-like and helium-like species of N, O,
Ne, and Fe, a narrow O VII RRC, and fluorescent emission from cold Fe. We use
the narrow RRC and the He-alpha triplets to constrain the temperature and
density of the (photoionized) gas. By comparing spectra from different
superorbital phases, we attempt to isolate the contributions to line emission
from the accretion disk and the stellar wind. There is also evidence for highly
ionized iron redshifted and blueshifted by ~25,000 km/s. We argue that this
emission originates in the inner accretion disk, and show that the emission
line properties in LMC X-4 are natural consequences of accretion disk
precession.Comment: 12 pages, 8 figures, uses emulateap
X-rays Studies of the Solar System
X-ray observatories contribute fundamental advances in Solar System studies
by probing Sun-object interactions, developing planet and satellite surface
composition maps, probing global magnetospheric dynamics, and tracking
astrochemical reactions. Despite these crucial results, the technological
limitations of current X-ray instruments hinder the overall scope and impact
for broader scientific application of X-ray observations both now and in the
coming decade. Implementation of modern advances in X-ray optics will provide
improvements in effective area, spatial resolution, and spectral resolution for
future instruments. These improvements will usher in a truly transformative era
of Solar System science through the study of X-ray emission.Comment: White paper submitted to Astro2020, the Astronomy and Astrophysics
Decadal Surve
Improving XMM-Newton EPIC pn data at low energies: method and application to the Vela SNR
High quantum efficiency over a broad spectral range is one of the main
properties of the EPIC pn camera on-board XMM-Newton. The quantum efficiency
rises from ~75% at 0.2 keV to ~100% at 1 keV, stays close to 100% until 8 keV,
and is still ~90% at 10 keV. The EPIC pn camera is attached to an X-ray
telescope which has the highest collecting area currently available, in
particular at low energies (more than 1400 cm2 between 0.1 and 2.0 keV). Thus,
this instrument is very sensitive to the low-energy X-ray emission. However,
X-ray data at energies below ~0.2 keV are considerably affected by detector
effects, which become more and more important towards the lowest transmitted
energies. In addition to that, pixels which have received incorrect offsets
during the calculation of the offset map at the beginning of each observation,
show up as bright patches in low-energy images. Here we describe a method which
is not only capable of suppressing the contaminations found at low energies,
but which also improves the data quality throughout the whole EPIC pn spectral
range. This method is then applied to data from the Vela supernova remnant.Comment: Proc. SPIE Vol. 5488: Astronomical Telescopes and Instrumentation, UV
- Gamma-Ray Space Telescope Systems, Eds. Guenther Hasinger and Martin J.
Turner, 22-24 June 2004, Glasgow, Scotland United Kingdo