Modified Einstein's gravity to probe the sub- and super-Chandrasekhar limiting mass white dwarfs: a new perspective to unify under- and over-luminous type Ia supernovae

Abstract

Type Ia supernovae (SNeIa), used as one of the standard candles in astrophysics, are believed to form when the mass of the white dwarf approaches Chandrasekhar mass limit. However, observations in last few decades detected some peculiar SNeIa, which are predicted to be originating from white dwarfs of mass much less than the Chandrasekhar mass limit or much higher than it. Although the unification of these two sub-classes of SNeIa was attempted earlier by our group, in this work, we, for the first time, explain this phenomenon in terms of just one property of the white dwarf which is its central density. Thereby we do not vary the fundamental parameters of the underlying gravity model in the contrary to the earlier attempt. We effectively consider higher order corrections to the Starobinsky-f (R) gravity model to reveal the unification. We show that the limiting mass of a white dwarf is ∼ M ⊙ for central density ρ c ∼ 1.4 × 10 8 g/cc, while it is ∼ 2.8M ⊙ for ρ c ∼ 1.6 × 10 10 g/cc under the same model parameters. We further confirm that these models are viable with respect to the solar system test. This perhaps enlightens very strongly the long standing puzzle lying with the predicted variation of progenitor mass in SNeIa.

Asymptotically flat vacuum solution in modified theory of Einstein’s gravity

“…In other words, the metric is not asymptotically flat. In this paper, we have explicitly shown that we can still obtain asymp- in cosmology to explain acceleration expansion of the universe, ourselves earlier (e.g., O(R >1 ) = αR 2 (1 − γR) and αR 2 e −γR ) [26] in astrophysics to explain peculiar over-and under-luminous SNeIa, and others (e.g., O(R >1 ) = γR 2 + β R 3 ) [21] in various astrophysical and cosmological contexts. There are many properties associated with black hole sources, e.g.…”

Continuous gravitational waves from magnetized white dwarfs

“…Many researchers proposed different models to explain these exceedingly massive WDs (e.g. Das & Mukhopadhyay 2013;Kalita & Mukhopadhyay 2018;Ong 2018). In this article, we show that in the presence of magnetic fields and rotation, the mass of WDs can increase significantly and eventually they can efficiently emit continuous gravitational radiation.…”

“…Some of the massive black hole binaries may create confusion noise too, which can easily be removed with proper source modeling, but this is beyond the scope of this work. A similar exploration has also been carried out in the case of neutron stars (Kalita & Mukhopadhyay 2018). Table 1. LGW and LEM for WDs consideringṖ = 10 -15 Hz s -1 and χ = 3 • .…”

Gravitational Wave in f(R) Gravity: Possible Signature of Sub- and Super-Chandrasekhar Limiting-mass White Dwarfs

“…Eventually, researchers have proposed a large number of modifications to GR, e.g., various f (R) gravity models, to elaborate the physics of the different astronomical systems, such as the massive neutron stars (Astashenok et al 2013(Astashenok et al , 2014, accretion disk around the compact object (Multamäki and Vilja 2006;Pun et al 2008;Pérez et al 2013;Kalita & Mukhopadhyay 2019a), and many more. Our group has also shown that using the suitable forms of f (R) gravity, we can unify the physics of all WDs, including those possessing sub-and super-Chandrasekhar limiting masses (Das & Mukhopadhyay 2015;Kalita & Mukhopadhyay 2018). We showed that by fixing the parameters in a viable f (R) gravity model such that it satisfies the solar system test (Guo 2014), one can obtain the sub-Chandrasekhar limiting-mass WDs at a relatively low density and super-Chandrasekhar WDs at high density (Kalita & Mukhopadhyay 2018).…”