An insight into the world of interacting supernovae

Shivalik HEPCATS Meeting Speaker : Anjasha Gangopadhyay Aryabhatta Research Institute of observational sciencES (ARIES), Nainital In collaboration with: Dr. Kuntal Misra 30-07-2020 Outline of the talk : ❏ Introduction to supernovae and their classification ❏ What are interacting supernovae and why study them ??? ❏ Optical studies of interacting supernovae : SNe 2012ab (type IIn) and 2019uo (type Ibn) ❏ A brief summary of the results Tycho Brahe observed supernova SN 1572 Supernovae are the giant stellar explosions that or Cassiopeia B in the constellation Cassiopeia! briefly outshines the whole galaxy radiating a huge amount of energy! In 185 AD, Chinese astronomers first recorded the appearance of a bright star in sky.

Telescope observations started from Mount Wilson Kasliwal et al. Observatory in 1935. 2011, LSST team 2017 Bersten et al. 2013 Why study these SNe ? Li et al. 2011 Less in number, unique.

Type IIn and Ibn SNe in particular very

less in number. Studying each event is

unique and interesting. Very few

statistical studies done so far.

Also, very less direct evidence of Along with this, only 31 type Ibn SNe have been detected so far. progenitors so far. Interaction is also significant in other wavelengths. Interacting SNe: SN 2012ab (A type IIn SNe) : Smith et al. 2017

Gangopadhyay et al. 2020c Spectroscopic features of a type Ibn supernova :

Gangopadhyay et al. 2020a

Narrow emission lines of Helium are seen!

Typical of a interaction with a Wolf-Rayet atmosphere! What are flash ionization signatures ? ● SNe embedded in dense CSM may show emission lines owing to recombination of shock flash (t < 10 days) with CSM. ● Prominent lines of He II, CIII Ȧ features are seen. ● SN 2019uo is the second type Ibn SN after 2010al to show such signatures. ● Again evident of a Wolf-Rayet scenario!

Gangopadhyay et al. 2020a Asymmetric line profiles of the interacting supernovae (SN 2012ab) :

Removed host galaxy contribution.

Tried fitting Gaussian profiles to explain the asymmetry.

Existence of a narrow, intermediate width and a broad component.

Gangopadhyay et al. 2020c Typical photometric features (SNe 2012ab and 2019uo) :

Gangopadhyay et al. 2020c,a Three recent cases : Type Ib turned to type IIn---> 13 years post explosion

Detected with KECK.

Similar case for SN 2014C

Mauerhan et al. 2018 Some take away points :

● Interacting supernovae are not a class but any kind of supernovae can become interacting if they have a dense CSM to interact with. ● Light curve features are overall similar, however, spectral features show distinct narrow emission lines of H/He depending on the type of SNe. ● Spectroscopic features show a highly asymmetric configuration. ● Long term and persistent optical observations of many SNe of other types can help in detecting interaction signatures. We are all stars. Something happens to burst us open and think we are dying ; we are actually turning into supernova . And then when we look at ourselves again, we see that we’re suddenly more beautiful than we ever were before !!! -C. Joybell