14 research outputs found
Cross-calibration of Suzaku XIS and XMM-Newton EPIC using clusters of galaxies
We extend a previous cross-calibration study by the International
Astronomical Consortium for High Energy Calibration (IACHEC) on
XMM-Newton/EPIC, Chandra/ACIS and BeppoSAX/MECS X-ray instruments with clusters
of galaxies to Suzaku/XIS instruments. Our aim is to study the accuracy of the
energy-dependent effective area calibration of the XIS instruments by
comparison of spectroscopic temperatures, fluxes and fit residuals obtained
with Suzaku/XIS and XMM-Newton/EPIC-pn for the same cluster. The temperatures
measured in the hard 2.0-7.0 keV energy band with all instruments are
consistent within 5 %. However, temperatures obtained with the XIS instruments
in the soft 0.5-2.0 keV band disagree by 9-29 %. We investigated residuals in
the XIS soft band, which showed that if XIS0 effective area shape is accurately
calibrated, the effective areas of XIS1 and XIS3 are overestimated below 1.0
keV (or vice versa). Adjustments to the modelling of the column density of the
XIS contaminant in the 3-6 arcmin extraction region while forcing consistent
emission models in each instrument for a given cluster significantly improved
the fits. The oxygen column density in XIS1 and XIS3 contaminant must be
increased by 1-2E17 cm^-2 in comparison to the values implemented in the
current calibration, while the column density of the XIS0 contaminant given by
the analysis is consistent with the public calibration. XIS soft band
temperatures obtained with the modification to the column density of the
contaminant agree better with temperatures obtained with the EPIC-pn instrument
of XMM-Newton, than with those derived using the Chandra-ACIS instrument.
However, comparison of hard band fluxes obtained using Suzaku-XIS to fluxes
obtained using the Chandra-ACIS and EPIC-pn instruments proved inconclusive.Comment: 24 pages, 27 figures, accepted for publication in Astronomy &
Astrophysic
CFHTLenS: weak lensing calibrated scaling relations for low-mass clusters of galaxies
We present weak lensing and X-ray analysis of 12 low-mass clusters from the Canada–France–Hawaii Telescope Lensing Survey and XMM-CFHTLS surveys. We combine these systems with high-mass systems from Canadian Cluster Comparison Project and low-mass systems from Cosmic Evolution Survey to obtain a sample of 70 systems, spanning over two orders of magnitude in mass. We measure core-excised L_X–T_X, M–L_X and M–T_X scaling relations and include corrections for observational biases. By providing fully bias-corrected relations, we give the current limitations for L_X and T_X as cluster mass proxies. We demonstrate that T_X benefits from a significantly lower intrinsic scatter at fixed mass than L_X. By studying the residuals of the bias-corrected relations, we show for the first time using weak lensing masses that galaxy groups seem more luminous and warmer for their mass than clusters. This implies a steepening of the M–L_X and M–T_X relations at low masses. We verify the inferred steepening using a different high-mass sample from the literature and show that variance between samples is the dominant effect leading to discrepant scaling relations. We divide our sample into subsamples of merging and relaxed systems, and find that mergers may have enhanced scatter in lensing measurements, most likely due to stronger triaxiality and more substructure. For the L_X–T_X relation, which is unaffected by lensing measurements, we find the opposite trend in scatter. We also explore the effects of X-ray cross-calibration and find that Chandra calibration leads to flatter L_X–T_X and M–T_X relations than XMM–Newton
XMM-Newton and INTEGRAL analysis of the Ophiuchus cluster of galaxies
We investigated the non-thermal hard X-ray emission in the Ophiuchus cluster
of galaxies. Our aim was to characterise the physical properties of the
non-thermal component and its interaction with the cosmic microwave background.
We performed spatially resolved spectroscopy and imaging using XMM-Newton data
to model the thermal emission. Combining this with INTEGRAL ISGRI data, we
modeled the 0.6-140 keV band total emission in the central 7 arcmin region. The
models that best describe both PN and ISGRI data contain a power-law component
with a photon index in a range 2.2-2.5. This component produces ~10% of the
total flux in the 1-10 keV band. The pressure of the non-thermal electrons is
~1% of that of the thermal electrons. Our results support the scenario whereby
a relativistic electron population, which produces the recently detected radio
mini-halo in Ophiuchus, also produces the hard X-rays via inverse compton
scattering of the CMB photons. The best-fit models imply a differential
momentum spectrum of the relativistic electrons with a slope of 3.4-4.0 and a
magnetic field strength B=0.05-0.15 microG. The lack of evidence for a recent
major merger in the Ophiuchus center allows the possibility that the
relativistic electrons are produced by turbulence or hadronic collisions.Comment: Accepted for publication in Astronomy and Astrophysics, v2 includes
some text improvement
BRIGHTEST X-RAY CLUSTERS OF GALAXIES IN THE CFHTLS WIDE FIELDS : CATALOG AND OPTICAL MASS ESTIMATOR
Peer reviewe
CFHTLenS: weak lensing calibrated scaling relations for low-mass clusters of galaxies
We present weak lensing and X-ray analysis of 12 low-mass clusters from the Canada-France-Hawaii Telescope Lensing Survey and XMM-CFHTLS surveys. We combine these systems with high-mass systems from Canadian Cluster Comparison Project and low-mass systems from Cosmic Evolution Survey to obtain a sample of 70 systems, spanning over two orders of magnitude in mass. We measure core-excised LX-TX, M-LX and M-TX scaling relations and include corrections for observational biases. By providing fully bias-corrected relations, we give the current limitations for LX and TX as cluster mass proxies. We demonstrate that TX benefits from a significantly lower intrinsic scatter at fixed mass than LX. By studying the residuals of the bias-corrected relations, we show for the first time using weak lensing masses that galaxy groups seem more luminous and warmer for their mass than clusters. This implies a steepening of the M-LX and M-TX relations at low masses. We verify the inferred steepening using a different high-mass sample from the literature and show that variance between samples is the dominant effect leading to discrepant scaling relations. We divide our sample into subsamples of merging and relaxed systems, and find that mergers may have enhanced scatter in lensing measurements, most likely due to stronger triaxiality and more substructure. For the LX-TX relation, which is unaffected by lensing measurements, we find the opposite trend in scatter. We also explore the effects of X-ray cross-calibration and find that Chandra calibration leads to flatter LX-TX and M-TX relations than XMM-Newto
CFHTLenS: Weak lensing calibrated scaling relations for low mass clusters of galaxies
We present weak lensing and X-ray analysis of 12 low mass clusters from the
CFHTLenS and XMM-CFHTLS surveys. We combine these systems with high-mass
systems from CCCP and low-mass systems from COSMOS to obtain a sample of 70
systems, spanning over two orders of magnitude in mass. We measure core-excised
Lx-Tx, M-Lx and M-Tx scaling relations and include corrections for
observational biases. By providing fully bias corrected relations, we give the
current limitations for Lx and Tx as cluster mass proxies. We demonstrate that
Tx benefits from a significantly lower intrinsic scatter at fixed mass than Lx.
By studying the residuals of the bias corrected relations, we show for the
first time using weak lensing masses that galaxy groups seem more luminous and
warmer for their mass than clusters. This implies a steepening of the M-Lx and
M-Tx relations at low masses. We verify the inferred steepening using a
different high mass sample from the literature and show that variance between
samples is the dominant effect leading to discrepant scaling relations. We
divide our sample into subsamples of merging and relaxed systems, and find that
mergers may have enhanced scatter in lensing measurements, most likely due to
stronger triaxiality and more substructure. For the Lx-Tx relation, which is
unaffected by lensing measurements, we find the opposite trend in scatter. We
also explore the effects of X-ray cross-calibration and find that Chandra
calibration leads to flatter Lx-Tx and M-Tx relations than XMM-Newton.Comment: Analysis modified to include bias correction. Updated CCCP
measurements. Comments are welcome, submitted to MNRAS, 26 pages, 20 figure
Weak lensing calibrated M-T scaling relation of galaxy groups in the COSMOS field
The scaling between X-ray observables and mass for galaxy clusters and groups is instrumental for cluster-based cosmology and an important probe for the thermodynamics of the intracluster gas. We calibrate a scaling relation between the weak lensing mass and X-ray spectroscopic temperature for 10 galaxy groups in the COSMOS field, combined with 55 higher-mass clusters from the literature. The COSMOS data includes Hubble Space Telescope imaging and redshift measurements of 46 source galaxies per arcminute2, enabling us to perform unique weak lensing measurements of low-mass systems. Our sample extends the mass range of the lensing calibrated M-T relation an order of magnitude lower than any previous study, resulting in a power-law slope of . The slope is consistent with the self-similar model, predictions from simulations, and observations of clusters. However, X-ray observations relying on mass measurements derived under the assumption of hydrostatic equilibrium have indicated that masses at group scales are lower than expected. Both simulations and observations suggest that hydrostatic mass measurements can be biased low. Our external weak lensing masses provide the first observational support for hydrostatic mass bias at group level, showing an increasing bias with decreasing temperature and reaching a level of 30%-50% at 1 keV