Novel compositions and methods for trehalose phospholipids

Provided herein are compositions of trehalose phospholipids and uses thereof, e.g., compounds and compositions comprising 6,6'-diphosphatidyltrehalose (diPT) and analogs thereof with modifications of the diPT chemical scaffold, that bind and agonize Mincle, and the use thereof as adjuvants

SNLS Spectroscopy: Testing for Evolution in Type Ia Supernovae

Aims: We present a quantitative study of a new data set of high redshift Type Ia supernovae spectra, observed at the Gemini telescopes during the first 34 months of the Supernova Legacy Survey. During this time 123 supernovae candidates were observed, of which 87 have been identified as SNe Ia at a median redshift of z=0.720. Spectra from the entire second year of the survey and part of the third year (59 total SNe candidates with 46 confirmed SNe Ia) are published here for the first time. The spectroscopic measurements made on this data set are used determine if these distant SNe comprise a population similar to those observed locally. Methods: Rest-frame equivalent width and ejection velocity measurements are made on four spectroscopic features. Corresponding measurements are presented for a set of 167 spectra from 24 low-z SNe Ia from the literature. Results: We show that there exists a sample at high redshift with properties similar to nearby SNe. No significant difference was found between the distributions of measurements at low and high redsift for three of the features. The fourth feature displays a possible difference that should be investigated further. Correlations between Type Ia SNe properties and host galaxy morphology were also found to be similar at low and high z, and within each host galaxy class we see no evidence for redshift-evolution in SN properties. A new correlation between SNe Ia peak magnitude and the equivalent width of SiII absorption is presented. We demonstrate that this correlation reduces the scatter in SNe Ia luminosity distances in a manner consistent with the lightcurve shape-luminosity corrections that are used for Type Ia SNe cosmology. Conclusions: We show that this new sample of SNLS SNe Ia has spectroscopic properties similar to nearby objects. (Abridged)Comment: Accepted for publication in Astronomy and Astrophysic

Berkeley Supernova Ia Program II: Initial Analysis of Spectra Obtained Near Maximum Brightness

In this second paper in a series we present measurements of spectral features of 432 low-redshift (z < 0.1) optical spectra of 261 Type Ia supernovae (SNe Ia) within 20 d of maximum brightness. The data were obtained from 1989 through the end of 2008 as part of the Berkeley SN Ia Program (BSNIP) and are presented in BSNIP I (Silverman et al. 2012). We describe in detail our method of automated, robust spectral feature definition and measurement which expands upon similar previous studies. Using this procedure, we attempt to measure expansion velocities, pseudo-equivalent widths (pEW), spectral feature depths, and fluxes at the centre and endpoints of each of nine major spectral feature complexes. We investigate how velocity and pEW evolve with time and how they correlate with each other. Various spectral classification schemes are employed and quantitative spectral differences among the subclasses are investigated. Several ratios of pEW values are calculated and studied. The so-called Si II ratio, often used as a luminosity indicator (Nugent et al. 1995), is found to be well correlated with the so-called "SiFe" ratio and anticorrelated with the analogous "SSi ratio," confirming the results of previous studies. Furthermore, SNe Ia that show strong evidence for interaction with circumstellar material or an aspherical explosion are found to have the largest near-maximum expansion velocities and pEWs, possibly linking extreme values of spectral observables with specific progenitor or explosion scenarios. [Abridged]Comment: 73 pages, 18 figures, 15 tables, revised version re-submitted to MNRAS. Measured values of the spectral features (i.e., Appendix B) will be publicly available when the paper is accepte

Carbon Detection in Early-Time Optical Spectra of Type Ia Supernovae

While O is often seen in spectra of Type Ia supernovae (SNe Ia) as both unburned fuel and a product of C burning, C is only occasionally seen at the earliest times, and it represents the most direct way of investigating primordial white dwarf material and its relation to SN Ia explosion scenarios and mechanisms. In this paper, we search for C absorption features in 188 optical spectra of 144 low-redshift (z < 0.1) SNe Ia with ages <3.6 d after maximum brightness. These data were obtained as part of the Berkeley SN Ia Program (BSNIP; Silverman et al. 2012) and represent the largest set of SNe Ia in which C has ever been searched. We find that ~11 per cent of the SNe studied show definite C absorption features while ~25 per cent show some evidence for C II in their spectra. Also, if one obtains a spectrum at t < -5 d, then there is a better than 30 per cent chance of detecting a distinct absorption feature from C II. SNe Ia that show C are found to resemble those without C in many respects, but objects with C tend to have bluer optical colours than those without C. The typical expansion velocity of the C II {\lambda}6580 feature is measured to be 12,000-13,000 km/s, and the ratio of the C II {\lambda}6580 to Si II {\lambda}6355 velocities is remarkably constant with time and among different objects with a median value of ~1.05. While the pseudo-equivalent widths (pEWs) of the C II {\lambda}6580 and C II {\lambda}7234 features are found mostly to decrease with time, we see evidence of a significant increase in pEW between ~12 and 11 d before maximum brightness, which is actually predicted by some theoretical models. The range of pEWs measured from the BSNIP data implies a range of C mass in SN Ia ejecta of about (2-30) * 10^-3 M_Sun.Comment: 20 pages, 11 figures, 4 tables, revised version re-submitted to MNRA

Optical and ultraviolet spectroscopic analysis of SN 2011fe at late times

We present optical spectra of the nearby Type Ia supernova SN 2011fe at 100, 205, 311, 349, and 578 days post-maximum light, as well as an ultraviolet spectrum obtained with Hubble Space Telescope at 360 days post-maximum light. We compare these observations with synthetic spectra produced with the radiative transfer code PHOENIX. The day +100 spectrum can be well fit with models which neglect collisional and radiative data for forbidden lines. Curiously, including this data and recomputing the fit yields a quite similar spectrum, but with different combinations of lines forming some of the stronger features. At day +205 and later epochs, forbidden lines dominate much of the optical spectrum formation; however, our results indicate that recombination, not collisional excitation, is the most influential physical process driving spectrum formation at these late times. Consequently, our synthetic optical and UV spectra at all epochs presented here are formed almost exclusively through recombination-driven fluorescence. Furthermore, our models suggest that the ultraviolet spectrum even as late as day +360 is optically thick and consists of permitted lines from several iron-peak species. These results indicate that the transition to the "nebular" phase in Type Ia supernovae is complex and highly wavelength-dependent.Comment: 22 pages, 21 figuress, 1 table, submitted to MNRA