Dr Jasmina Lazendic-Galloway

Margaret Clayton Research Fellow PhD, Astrophysics, University of Sydney, 2003 BSc (Hons), University of Western Sydney Nepean, 1998 Phone +61 (3) 9905 1725 FAX +61 (3) 9905 3637 Email:Jasmina Lazendic-Galloway

RESEARCH INTERESTS

My primary research areas of interest are supernova remnants and neutron stars. A supernova explosion marks the endpoint of a massive star evolution, resulting in an expanding shell, the supernova remnant (SNR), consisting of a blast wave accompanied by slower moving stellar ejecta. Thus, SNRs are often observed as whole or partial shells of optical, X-ray and radio emission. The input of energy and nuclear fusion products into the interstellar medium make SNRs, dynamically and chemically, one of the most important objects in galaxies. In particular, I am interested in:

Image credit: Life cycles of stars from NASA's Imagine the Universe . The bottom diagram shows evolution of a normal mass star, like our Sun: the star is burning its fuel slowly, and towards the end of the life goes through a red giant phase, ending its life as a white dwarf, and then brown dwarf. The upper diagram shows the evolution of a massive star: the star is burning its fuel more rapidly, goes through a supernova stage and explodes, creating a supernova remnant shell that dissipates back into interstellar medium. The supernova explosion can also leave behind a compact stellar core, a neutron star or a black hole.

• the general physical properties of SNRs, using mainly X-ray and radio observations - as telescopes at different wavelengths continue to improve in sensitivity and spatial resolution, we are able to study SNRs in more detail, rather than their spatially averaged properties;
• a special class of "mixed-morphology" remnants - an intriguing class of SNRs that show different morphology in X-ray and radio band, and, more importantly, different X-ray properties than expected from standard SNR theory;
• using high-resolution X-ray imaging and spectroscopy for SNR studies - instruments in X-ray band are approaching optical, IR, and UV bands in their ability to measure precise kinematics and add a third dimension to the data;
• studying particle acceleration in SNRs using non-thermal X-ray emission and TeV Gamma-ray emission in attempt to solve the question about the origin of low-energy cosmic rays;
• studying the interaction of SNRs with dense molecular clouds using X-ray, millimetre and infrared observations - the shocks driven by SNRs into dense molecular clouds compress, accelerate and heat the gas, exciting higher molecular transitions and activating chemical reactions forbidden in cold molecular clouds;

Radio and X-ray images of supernova remnant MSH 61-11A.
Overlay of radio data (contours) from the MOST telescope and X-ray data (colour image) from the ASCA satellite.	Overlay of the same radio data (contours) and X-ray data (colour image) from the Chandra satellite.

This remnant belongs to a class of mixed-morphology remnants: while radio morphology shows a clear shell, X-ray emission is concentrated mostly in the centre. The instrumental advances allow for more detailed studies of this object: diffuse emission seen in the ASCA image is resolved into diffuse and clumpy structures by Chandra.

Neutron stars are another by-product of supernova explosions - the collapsed stella core forms a fast-rotating compact stellar object called a pulsar or, in the extreme case, a black hole. While there are plenty of isolated neutron stars for which their supernova remnant shell has been dissipated into the surrounding medium, detecting and studying neutron stars still associated with supernova remnants is very important due to the present dearth of neutron star-SNR associations. The Chandra X-ray Observatory has made significant advances in studying all types of neutron stars, primarily because of its superior sub-arcsecond spatial resolution. As well as helping to shed light on many known objects, it has also revealed some unusual neutron stars that do not seem to exhibit the expected properties, mainly fast rotation and high magnetic field. One class of such objects is called Compact Central Objects (CCOs). There is only a handful of these objects so identification of new CCOs and more detailed studies of known CCOs provide valuable information to unravel the nature of these sources.

Recent publications:

Lazendic J. S., Dewey D., Schulz N. S., and Canizares C. R., (2006), The Kinematic and Plasma Properties of X-ray Knots in Casssiopea~A from the Chandra HETGS, ApJ, vol. 651, p. 250; ADS link

Lazendic J. S., Slane P. O., (2006), Enhanced abundances in three large-diameter mixed-morphology supernova remnants, ApJ, vol. 647, p. 350; ADS link

Lazendic J. S., Slane P. O., Chen Y., Hughes J. P., Dame T.M. (2005), Chandra detection of ejecta in the small-diameter supernova remnant G349.7+0.2, ApJ, vol. 618, p. 733; ADS link

Lazendic, J. S., Burton, M., Wardle, M., Yusef-Zadeh, F., Green, A., (2004), Shocked molecular hydrogen towards the Tornado nebula, MNRAS, vol. 354, p. 393; ADS link

Lazendic J. S., Slane P., Gaensler B., Reynolds, S., Plucinsky P., Hughes J. P. (2004), A high-resolution study of nonthermal radio and X-ray emission from SNR G347.3-0.5, ApJ, vol. 602, p. 271; ADS link

Lazendic J. S., Dickel J. R., Jones P. A. (2003), SNR candidates in the 30 Doradus nebula, ApJ, vol. 596, p. 287; ADS link

Lazendic J. S., Slane P., Gaensler B., Plucinsky P., Hughes J. P., Galloway D. K., Crawford F. (2003), X-ray observations of the compact central object in the supernova remnant G347.3-0.5, ApJ, vol. 593, p. 27L; ADS link

ApJ = The Astrophysical Journal
MNRAS = Monthly Notices Royal Astronomical Society