A Multi-Wavelength Study of the Western Lobe of W50 Powered by the Galactic Microquasar SS 433

W50 remains the only supernova remnant (SNR) confirmed to harbor a microquasar: the powerful enigmatic source SS 433. Our past study of this fascinating SNR revealed two X-ray lobes distorting the radio shell as well as non-thermal X-rays at the site of interaction between the SS 433 eastern jet and the eastern lobe of W50. In this paper we present the results of a 75 ksec CHANDRA ACIS-I observation of the peak of W50-west targeted to 1) determine the nature of the X-ray emission and 2) correlate the X-ray emission with that in the radio and infrared domains. We have confirmed that at the site of interaction between the western jet of SS 433 and dense interstellar gas the X-ray emission is non-thermal in nature. The helical pattern observed in radio is also seen with CHANDRA. No correlation was found between the infrared and X-ray emission.Comment: A refereed publication, submitted Sept. 30, 2004, accepted Jan. 12, 2005, to appear in Advances in Space Research. 7 pages, including 4 figures (3 color) & 1 table (the resolution of most figures has been reduced for astro-ph submission only). A gzipped postscript or pdf version of the paper with high-resolution images can be downloaded from: http://aurora.physics.umanitoba.ca/~moldowan/Astro-Ph

Spatial Distribution of Metal Emissions in SNR 3C 397 Viewed with Chandra and XMM

We present X-ray equivalent width imaging of the supernova remnant (SNR) 3C 397 for Mg He\alpha, Si He\alpha, S He\alpha, and Fe K\alpha complex lines with the Chandra and XMM-Newton observations. The images reveal that the heavier the element is, the smaller the extent of the element distribution is. The Mg emission is evidently enhanced in the southeastern blow-out region, well along the radio boundary there, and appears to partially envelope the eastern Fe knot. Two bilateral hat-like Si line-emitting structures are along the northern and southern borders, roughly symmetric with respect to the southeast-northwest elongation axis. An S line-emitting shell is located just inner to the northern radio and IR shell, indicating of a layer of reversely shocked sulphur in the ejecta. A few enhanced Fe features are basically aligned along the diagonal of the rectangular shape of the SNR, which implicates an early asymmetric SN explosion.Comment: 4 pages, 4 figures, appears in Science China Physics, Mechanics & Astronomy, 2010, 53 (Suppl.1), 267-27

XMM-Newton observation of the supernova remnant Kes 78 (G32.8-0.1):Evidence of shock-cloud interaction

The Galactic supernova remnant Kes 78 is surrounded by dense molecular clouds, whose projected position overlaps with the extended HESS gamma-ray source HESS J1852-000. The X-ray emission from the remnant has been recently revealed by Suzaku observations, which have shown indications for a hard X-ray component in the spectra, possibly associated with synchrotron radiation. We aim at describing the spatial distribution of the physical properties of the X-ray emitting plasma and at revealing the effects of the interaction of the remnant with the inhomogeneous ambient medium. We also aim at investigating the origin of the gamma-ray emission, which may be Inverse Compton radiation associated with X-ray synchrotron emitting electrons or hadronic emission originating from the impact of high energy protons on the nearby clouds. We analyzed an XMM-Newton EPIC observation of Kes 78 by performing image analysis and spatially resolved spectral analysis on a set of three regions. We tested our findings against the observations of the 12CO and 13CO emission in the environment of the remnant. We revealed the complex X-ray morphology of Kes 78 and found variations of the spectral properties of the plasma, with significantly denser and cooler material at the eastern edge of the remnant, which we interpret as a signature of interaction with a molecular cloud. We also exclude the presence of narrow filaments emitting X-ray synchrotron radiation. Assuming that the very high energy gamma-ray emission is associated with Kes 78, the lack of synchrotron emission rules out a leptonic origin. A hadronic origin is further supported by evidence for interaction of the remnant with a dense molecular cloud in its eastern limb.Comment: Accepted for publication in A&

Prediction of vascular aging based on smartphone acquired PPG signals

Photoplethysmography (PPG) measured by smartphone has the potential for a large scale, non-invasive, and easy-to-use screening tool. Vascular aging is linked to increased arterial stiffness, which can be measured by PPG. We investigate the feasibility of using PPG to predict healthy vascular aging (HVA) based on two approaches: machine learning (ML) and deep learning (DL). We performed data preprocessing, including detrending, demodulating, and denoising on the raw PPG signals. For ML, ridge penalized regression has been applied to 38 features extracted from PPG, whereas for DL several convolutional neural networks (CNNs) have been applied to the whole PPG signals as input. The analysis has been conducted using the crowd-sourced Heart for Heart data. The prediction performance of ML using two features (AUC of 94.7%) – the a wave of the second derivative PPG and tpr, including four covariates, sex, height, weight, and smoking – was similar to that of the best performing CNN, 12-layer ResNet (AUC of 95.3%). Without having the heavy computational cost of DL, ML might be advantageous in finding potential biomarkers for HVA prediction. The whole workflow of the procedure is clearly described, and open software has been made available to facilitate replication of the results

Prediction of vascular aging based on smartphone acquired PPG signals

Photoplethysmography (PPG) measured by smartphone has the potential for a large scale, non-invasive, and easy-to-use screening tool. Vascular aging is linked to increased arterial stiffness, which can be measured by PPG. We investigate the feasibility of using PPG to predict healthy vascular aging (HVA) based on two approaches: machine learning (ML) and deep learning (DL). We performed data preprocessing, including detrending, demodulating, and denoising on the raw PPG signals. For ML, ridge penalized regression has been applied to 38 features extracted from PPG, whereas for DL several convolutional neural networks (CNNs) have been applied to the whole PPG signals as input. The analysis has been conducted using the crowd-sourced Heart for Heart data. The prediction performance of ML using two features (AUC of 94.7%) \u2013 the a wave of the second derivative PPG and tpr, including four covariates, sex, height, weight, and smoking \u2013 was similar to that of the best performing CNN, 12-layer ResNet (AUC of 95.3%). Without having the heavy computational cost of DL, ML might be advantageous in finding potential biomarkers for HVA prediction. The whole workflow of the procedure is clearly described, and open software has been made available to facilitate replication of the results

A Broadband X-Ray Study of the Supernova Remnant 3C 397

We present an X-ray study of the radio bright supernova remnant (SNR) 3C 397 with ROSAT, ASCA, and RXTE. A central X-ray spot seen with the ROSAT High-Resolution Imager hints at the presence of a pulsar-powered component, and gives this SNR a composite X-ray morphology. Combined ROSAT and ASCA imaging show that the remnant is highly asymmetric, with its hard X-ray emission peaking at the western lobe. The spectrum of 3C 397 is heavily absorbed, and dominated by thermal emission with emission lines evident from Mg, Si, S, Ar and Fe. Single-component models fail to describe the spectrum, and at least two components are required. We use a set of non-equilibrium ionization (NEI) models (Borkowski et al. in preparation). The temperatures from the soft and hard components are 0.2 keV and 1.6 keV respectively. The corresponding ionization time-scales $n_0 t$ ($n_0$ being the pre-shock hydrogen density) are 6 $\times 10^{12}$ cm$^{-3}$ s and 6 $\times$ 10$^{10}$ cm$^{-3}$ s, respectively. The spectrum obtained with the Proportional Counter Array (PCA) of RXTE is contaminated by emission from the Galactic ridge, with only $\sim$ 15% of the count rate originating from 3C 397 in the 5-15 keV range. The PCA spectrum allowed us to confirm the thermal nature of the hard X-ray emission. A third component originating from a pulsar-driven component is possible, but the contamination of the source signal by the Galactic ridge did not allow us to find pulsations from any hidden pulsar. We discuss the X-ray spectrum in the light of two scenarios: a young ejecta-dominated remnant of a core-collapse SN, and a middle-aged SNR expanding in a dense ISM. Spatially resolved spectroscopy (with CHANDRA and XMM) is needed to differentiate between the two scenarios, and address the nature of the mysterious radio-quiet X-ray hot spot.Comment: 21 pages including 8 figures and 5 tables. Accepted for publication in the Astrophysical journa