I summarize some astrophysical phenomenon like gamma ray bursters, astrophysical proof of the existence of blackholes, Active galactic nuclei — as high energy neutrino sources, and some unsolved issues in supernova. I touch on the aspects where novel particle properties (like neutrino mass and magnetic moment) are invoked to understand the astronomical observations.

The astroparticle physics working group witnessed intense discussion and activity covering a broad range of topics ranging from supergravity and baryogenesis to compact stars and the large scale structure of the Universe. A summary of some of the subject areas in which collaborations were initiated during WHEPP-5 is presented below.

I discuss basic theory of effect of the properties of the cosmological relict neutrinos on the observations of the cosmic microwave background anisotropy.

The working group on astroparticle and neutrino physics at WHEPP-9 covered a wide range of topics. The main topics were neutrino physics at INO, neutrino astronomy and recent constraints on dark energy coming from cosmological observations of large scale structure and CMB anisotropy.

The BICEP2/Keck+PLANCK joint analysis of the 𝐵-model polarization and polarization by foreground dust sets an upper bound on the tensor-to-scalar ratio of 𝑟_0.05 < 0.12 at 95% CL. The popular Starorbinsky model Higgs-inflation or the conformally equivalent Higgs-inflation model allow low 𝑟 values (∼10⁻³). We survey the generalizations of the Starobinsky–Higgs models which would allow larger values (𝑟 ∼ 0.1). The Starobinsky–Higgs inflation models require an exponential potential which can be naturally derived from SUGRA models. We show that a variation of the no-scale SUGRA model can give rise to the generalized Starobinsky models which give large 𝑟. We also examine non-standard boundary conditions which would allow a large deviation of the tensor spectral index from the slow roll values and propose that the presence of a thermal component in the tensor spectrum arises from Gibbons–Hawking temperature of the de-Sitter space.