Does the Mass-Gap Hint at the Existence of New Types Compact Objects?

Abstract

The discovery of gravitational waves (GW) from the coalescence binary system reduces the mass-gap to (2.6 – 5) M⊙ . Hypothetical stars such as the super-Chandrasekhar mass white dwarf, quark star, boson star, electro weak star, grav-star, dark matter star , supermassive neutron star, etc may exist between neutron star (NS) and black hole (BH) within this range. Comparing the observed results with numerical calculations this author suggests the detected unseen companion compact object with mass 3.3 M⊙ in the binary J05215658 + 4359220 is a triaxially deformed quark star (or triaxial star). If this is correct, then the mass gap will again reduce from (2.6–5) M⊙ to (3.3 – 5) M⊙. Application of the solutions of the Vaidya-Tikekar Ansatz in modeling Einstein’s general relativity hints that the maximum mass of a compact object ~ 4.178 M⊙ (i.e., four times the solar mass) in realistic case. This author proposes that compact objects with higher masses are possible in a triaxially deformed compact state. As the lighter dark matter is five times more massive than the baryonic matter it is also suggested that further higher mass is possible when the compact object is triaxially deformed, consisting of lighter dark matter or unknown matter whose nature or form is not yet known to us. As the detection of gravitational waves can be a convenient method to collect evidence of quark stars (e.g. strange quark stars) or dark matter admixed with normal matter neutron stars we encourage the GW community to search for their electromagnetic counterparts during their observation of compact objects through LIGO or VIRGO.