Detection of hidden structures on all scales in amorphous materials and complex physical systems: basic notions and applications to networks, lattice systems, and glasses

Recent decades have seen the discovery of numerous complex materials. At the root of the complexity underlying many of these materials lies a large number of possible contending atomic- and larger-scale configurations and the intricate correlations between their constituents. For a detailed understanding, there is a need for tools that enable the detection of pertinent structures on all spatial and temporal scales. Towards this end, we suggest a new method by invoking ideas from network analysis and information theory. Our method efficiently identifies basic unit cells and topological defects in systems with low disorder and may analyze general amorphous structures to identify candidate natural structures where a clear definition of order is lacking. This general unbiased detection of physical structure does not require a guess as to which of the system properties should be deemed as important and may constitute a natural point of departure for further analysis. The method applies to both static and dynamic systems.Comment: (23 pages, 9 figures

One year of monitoring of the Type IIb supernova SN 2011dh

Optical $UBVRI$ photometry and low resolution spectroscopy of the type IIb supernova SN 2011dh in M51 are presented, covering the first year after the explosion. The light curve and spectral evolution are discussed. The early phase light curve evolution of SN 2011dh is very similar to SN 1993J and SN 2008ax. In the late phase, however, SN 2011dh declines faster than SN 1993J. The late phase decline in the $B$-band is steeper than in the $R$ and $I$ bands, indicating the possibility of dust formation. With a peak $V$-band absolute magnitude of $M_V = -17.123\pm0.18$ mag, SN 2011dh is a marginally faint type IIb event. The reddening corrected colour curves of SN 2011dh are found to be redder than other well studied type IIb supernovae. The bolometric light curve indicates $\sim$ 0.09 M$_\odot$ of $^{56}$Ni is synthesized during the explosion. The HeI lines were detected in the spectra during the rise to maximum. The nebular spectra of SN 2011dh show a box shaped emission in the red wing of the [OI] 6300-6363 \AA\ feature, that is attributed to H$\alpha$ emission from a shock excited circumstellar material. The analysis of nebular spectra indicates that $\sim 0.2$ M$_\odot$ of oxygen was ejected during the explosion. Further, the [CaII]/[OI] line ratio in the nebular phase is $\sim$ 0.7, indicating a progenitor with a main sequence mass of 10-15 M$_\odot$.Comment: Accepted for publication in MNRA

Supernova SN 2012dn: A spectroscopic clone of SN 2006gz

We present optical and UV analysis of the luminous type Ia supernova SN 2012dn covering the period $\sim -$11 to +109 days with respect to the $B$ band maximum, that occurred on JD 2456132.89 $\pm$ 0.19, with an apparent magnitude of $m_{B}^\text{max}$ = 14.38 $\pm$ 0.02. The absolute magnitudes at maximum in $B$ and $V$ bands are $M_{B}^\text{max} = -19.52 \pm 0.15$ and $M_{V}^\text{max} = -19.42 \pm 0.15$, respectively. SN 2012dn is marginally luminous compared to normal type Ia supernovae. The peak bolometric luminosity of $\log L_\text{bol}^\text{max} = 43.27 \pm 0.06$ erg s$^{-1}$ suggests that $0.82 \pm 0.12$ M$_\odot$ of $^{56}$Ni was synthesized in the explosion. The decline rate $\Delta m_{15}(B)_\text{true}= 0.92 \pm 0.04$ mag is lower than that of normal type Ia supernovae, and similar to the luminous SN 1991T. However, the photometric and spectroscopic behaviour of SN 2012dn is different from that of SN 1991T. Early phase light curves in $R$ and $I$ bands are very broad. The $I$ band peak has a plateau-like appearance similar to the super-Chandra SN 2009dc. Pre-maximum spectra show clear evidence of C\,{\sc ii} 6580 \AA\, line, indicating the presence of unburned materials. The velocity evolution of C\,{\ sc ii} line is peculiar. Except for the very early phase ($\sim-$13 d), the C\,{\sc ii} line velocity is lower than the velocity estimated using the Si\,{\sc ii} line. During the pre-maximum and close to maximum phase, to reproduce observed shape of the spectra, the synthetic spectrum code {\sc syn++} needs significantly higher blackbody temperature than those required for normal type Ia events. The photospheric velocity evolution and other spectral properties are similar to those of the carbon-rich SN 2006gz.Comment: Accepted for publication in MNRAS, 19 pages, 20 figure

Eprints@NML: Digital Repository of National Metallurgical Laboratory (CSIR),India

The National Metallurgical Laboratory (NML) of India established its EPrints repository in September 2009, providing its researchers with an easy solution for Open Access. This has allowed their researchers to promote their research and to draw an attention among their counterparts over the globe. By the end of this first year of operation, interest in their work has increased phenomenally and their repository has achieved a ten-fold increase in traffic, with over 80,000 document downloads per month and a cumulative total of 5 million hits