Research

The 2.56-m Nordic Optical Telescope. Image: E. Kankare.

NUTS2

The yearly supernova (SN) candidate discovery rate is increasing exponentially thanks to the revolution in time domain astronomy by large-scale all-sky transient surveys. The full scans of the entire night sky ensure the discovery of young, bright transients within an increasingly large volume of the local Universe in an unbiased way. NOT Unbiased Transient Survey 2 (NUTS2) is a Large observing programme at the 2.56-m Nordic Optical Telescope (NOT) to classify and follow up SNe, SN impostors, and tidal disruption events. NOT observations will play a fundamental role in addressing a whole host of science work packages, e.g.: (i) SN Ia progenitors and their explosion physics, (ii) the progenitors and rates of core-collapse SNe, (iii) nuclear transients, and (iv) extreme SNe. NUTS2 is led by PIs from Finland (E. Kankare) and Denmark. My research interests within NUTS2 are focussed on transients interacting with their circumstellar medium (e.g. Kankare et al. 2012, MNRAS, 424, 8552015, A&A, 581, L4) and recently highly energetic nuclear transients (Kankare et al. 2017, Nature Astronomy, 1, 865).

SUNBIRD

An IR image of LIRG IRAS 17138-1017 hosting SN 2008cs with a total line-of-sight extinction of A_V ~ 18 mag.  Image credit: Kankare et al; Travis Rector (University of Alaska); Gemini Observatory; NASA.

Luminous infrared galaxies (LIRGs; 10¹¹ L_Sun < L_IR < 10¹² L_Sun) have a factor of ~100 higher star formation (SF) and core-collapse supernova (CCSN) rates compared to those of normal spiral galaxies. Dust extinction already affects SNe in normal galaxies (e.g. Kankare et al. 2014, A&A, 572, A75). However, the number of CCSNe discovered in LIRGs has remained extremely modest due to the high host galaxy extinction and background contrast effects. Our international Supernovae UNmasked By Infra-Red Detection (SUNBIRD) collaboration has carried out high spatial resolution near-IR full adaptive optics (AO) programmes at 8-m class telescopes (VLT, Gemini, Keck) to search for highly obscured CCSNe in samples of LIRGs (e.g. Kankare et al. 2008, ApJ, 689, L9; 2012, ApJ, 744, L19; 2014, MNRAS, 440, 1052; 2021, A&A, 649, A134). The long-term goal of the project is to obtain a statistically significant sample to study the CCSN population in these galaxies and to derive robust extinction and missing fraction corrections for optical CCSN rates from the local to the high-redshift Universe.

Multi-messenger astronomy

The Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo collaboration has detected gravitational waves from compact (neutron star and stellar mass black hole) binary coalescence events. The merger of two inspiralling neutron stars (GW170817) was followed by the exciting discovery of the first electromagnetic kilonova counterpart. This confirmed several predictions and hypotheses, including neutron star mergers as the primary source of the light r-process elements (e.g. Smartt (incl. Kankare) et al. 2017, Nature, 551, 75). I am a part of the ENGRAVE (Electromagnetic Counterparts of Gravitational Wave sources at the Very Large Telescope) project, which is a ~200 member collaboration running a European Southern Observatory (ESO) VLT Large programme for the optical to mid-IR follow-up of electromagnetic counterparts of gravitational wave sources detected by LIGO/Virgo. I am the HAWK-I near-IR imager instrument scientist for ENGRAVE.