I am a post-doctoral researcher in the Astrophysics group at Warwick, starting in January 2014. My research is concerned primarily with observing the transient sky and revealing the culprits of these luminous events. I have particular interest in constraining the progenitors of core-collapse supernovae through observations of their explosions and the environments they inhabit within their hosts. Alongside this I study unusual or peculiar SNe, the progenitors of which are poorly understood, in the hopes of constraining models.
Some money plots
Peculiar transient progenitor age constraints:
SN2002cx-like supernovae progenitors are young: Their explosion sites trace the near-ultraviolet (NUV) light distribution of their hosts. NUV is a tracer of recent (up to ~100Myr) star-formation.
Ca-rich transients are old: Almost half of the sample lie on regions of no NUV emission.
This plot was constructed using pixel statistics of SN locations within their hosts in the ultraviolet (a tracer of star formation) - the abscissa is a measure of the brightness of the SN's location normalised to its host. Further details and analysis can be found in Lyman et al. (2013), including a similar plot for emission that shows SN2002cx-like supernovae have ages similar to supernovae type II, i.e. 50-80 Myr, and that Ca-rich transients are likely to be very old (Gyrs) from host-galaxy type distribution analyses.
The host systems of Ca-rich transients:
Ca-rich transients are not formed in globular clusters or dwarf galaxies: Very deep imaging at the explosion locations of nearby Ca-rich transients reveal nothing down to the images' limits, which are deeper than the globular cluster luminosity function (red histogram)
With large galactocentric offsets, the host systems of Ca-rich transients were though to be dwarf galaxies or perhaps globular clusters. The deep VLT data presented in Lyman et al. (2014) have upper limits fainter than dwarf galaxies, globular clusters and even individual massive stars. Since the stellar density is so low at these extreme offsets, and a large fraction of Ca-rich transients exhibit such offsets, the progenitor systems cannot be formed in situ at these large offsets and must be expelled from their host galaxies in, for example, kicked or dynamically ejected systems. See press release here.
Bolometric corrections for core-collapse supernovae:
The bolometric magnitude of a CCSN can be determined accurately from two-filter observations: Shown here for , the bolometric correction (BC) for CCSNe as a function of colour follows a tight relation.
The fits for BCs to many different optical colours are given in Lyman et al. (2014), with typical rms of data around the fits being mag.
Bolometric lightcurves of core-collapse supernovae:
A large catalogue of CCSN bolometric light curves: Constructed from only two-filter observations with treatment of the UV-optical-NIR and extended to longer wavelengths with a blackbody fit.
With a large sample of bolometric light curves, explosion parameter distributions are being investigated through analytical fits in Lyman et al. (submitted). Such explosion parameters provide tight constraints for explosion models, for example by revealing the amount of synthesised in supernovae. Furthermore, the distribution of ejecta masses has been shown to favour lower mass progenitors, most likely in binary systems, as the progenitors of the majority of stripped-envelope (i.e. type Ib/c) supernovae. This opens questions as to where the supernovae from very massive single (or detatched binary) stars are, and if they even produce a luminous supernova.