Radio observations of Supernova Remnants and the surrounding molecular gas

Supernova Remnants (SNRs) are believed to be the main source of Galactic cosmic rays (CR). The strong SNR shocks provide ideal acceleration sites for particles of at least 10^14 eV/nucleon. Radio continuum studies of SNRs carried out with good sensitivity and high angular resolution convey information about three main aspects of the SNRs: morphology, polarization and spectrum. Based on this information it is possible to localize sites of higher compression and particle acceleration as well as the orientation and degree of order of the magnetic fields, and in some cases even its intensity. All this information, when complemented with the study of the distribution and kinematics of the surrounding interstellar gas, results in a very useful dataset to investigate the role of SNRs as cosmic ray accelerators. In this presentation, I analyze the radio observations of SNRs and surrounding molecular clouds, showing the contribution of these studies to the understanding of the role of SNRs as factories of CRs.Comment: 6 pages, 2 figures. Invited review presented at the conference on Cosmic Rays and the Interstellar Medium (CRISM-2011) held in Montpellier (France), June 26- July 1. To be published in a special issue of Memorie della Societa Astronomica Italian

The molecular clump towards the eastern border of SNR G18.8+0.3

The eastern border of the SNR G18.8+0.3, close to an HII regions complex, is a very interesting region to study the molecular gas that it is probably in contact with the SNR shock front. We observed the aforementioned region using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3, and CS J=7-6 lines with an angular resolution of 22". To complement these observations, we analyzed IR, submillimeter and radio continuum archival data. In this work, we clearly show that the radio continuum "protrusion" that was early thought to belong to the SNR is an HII regions complex deeply embedded in a molecular clump. The new molecular observations reveal that this dense clump, belonging to an extended molecular cloud that surrounds the SNR southeast border, is not physically in contact with SNR G18.8+0.3, suggesting that the SNR shock front have not yet reached it or maybe they are located at different distances. We found some young stellar objects embedded in the molecular clump, suggesting that their formation should be approximately coeval with the SN explosion.Comment: Accepted for publication in A&A (Sept. 7, 2012

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

Radio and X-ray images of SNR G18.8+0.3 interacting with molecular clouds

New HI images from the VLA Galactic Plane Survey (VGPS) show clear absorption features associated with the supernova remnant (SNR) G18.8+0.3. High-resolution $^{13}$CO images reveal that molecular clouds overlap the radio filaments of G18.8+0.3. The $^{13}$CO emission spectrum over the full velocity range in the direction of G18.8+0.3 shows two molecular components with high brightness-temperatureand three molecular components with low brightness-temperature, all with respective HI absorption. This implies that these clouds are in front of G18.8+0.3. In the HI images, the highest velocity absorption feature seen against the continuum image of G18.8+0.3 is at 129 km s$^{-1}$, which corresponds to the tangent point in this direction. This yields a lower distance limit of 6.9 kpc for G18.8+0.3. Absence of absorption at negative velocities gives an upper distance limit of 15 kpc. The broadened profile at 20$\pm$5 km s$^{-1}$ in the $^{13}$CO emission spectra is a strong indicator of a possible SNR/CO cloud interaction. Thus, G18.8+0.3 is likely to be at the distance of about 12 kpc. The upper mass limit and mean density of the giant CO cloud at 20$\pm$5 km s$^{-1}$ are \sim 6 \times 10^{5} M_{\odot} and \sim 2 \times 10^{2} cm^{-3}. We find an atomic hydrogen column density in front of G18.8+0.3 of $N_{HI}$ \sim 2 \times 10^{22} cm^{-2}. The ROSAT PSPC observations show a diffuse X-ray enhancement apparently associated with part of the radio shell of G18.8+0.3. Assuming an association, the unabsorbed flux is 2.2 \times10^{-12} erg cm^{-2} s^{-1}, suggesting an intrinsic luminosity of 3.6 \times 10^{34} erg s^{-1} for G18.8+0.3.Comment: 8 pages, 6 figures, two tables, accepted by A&

Willpower and ego depletion: Useful constructs?

It is widely recognized that the ability to exert will and defy the temptation of short-term rewards in favor of long term goals has many significant implications and is predictive of increased well-being across many domains. The American Psychological Association characterizes willpower as “the psychological science of self-control”, and their recent survey regarding Americans’ perception of their own self-control, cited the lack of will-power as the primary reason they fail to follow through with making healthy life-style changes. The “strength” model of self-control conceptualizes willpower as a limited resource which cannot be sustained indefinitely. According to the model, expending effort to exert self-control results in a reduced ability for individuals to exert self-control in a subsequent task—a psychological state known as ego depletion. Numerous investigations have replicated this effect across multiple domains and have also examined the influence of variables that moderate ego depletion. However, recent regression analyses have strongly suggested that the effect size for ego depletion is substantially smaller than was originally computed. In addition, despite widespread acceptance in both the popular press and the scientific study of psychology, the strength model has come under criticism that it has evolved into an over-reaching and unfalsifiable theory that should be subsumed under a more comprehensive theory of self-control that integrates traditional influences on self-control, including motivation, learning, and self- efficacy

The psychology and science of happiness: What does the research say?

This paper surveys the scientific evidence regarding the nature of human happiness by drawing upon numerous studies in social science domains: namely psychology, but also related fields of business leadership and consulting, economics, and behavioral economics. Beginning with a definition and narrowing of the terminology, the review moves toward a brief sketch of measurement methods in the topic. Subjective well-being and happiness are then explored within the framework of psychological theories of happiness, including tension-reduction and goal attainment theories, activity and process theories, and genetic and biologic dispositional theory. Evolving views regarding hedonic adaptation as a key process underlying happiness is examined, as well as Lyubomirsky and Layous’ (2013) comprehensive model of happiness as a framework that encompasses the entire scope of psychological theories regarding happiness. Finally, the correlational evidence related to the various components of happiness is reviewed, concluding with the observation that although strong correlational evidence is linked to well-being, happiness is a concept that defies unequivocal causal attributions because it contains a complex amalgam of interrelated and bi-reciprocal variables