3D Radiation-hydrodynamic Simulations Resolving Interior of Rapidly Accreting Primordial Protostar

Kimura, Kazutaka,   Hosokawa, Takashi,   Sugimura, Kazuyuki,   & Fukushima, Hajime

要旨

Direct collapse of supermassive stars is a possible pathway to form supermassive black hole seeds at high redshifts. Whereas previous three-dimensional (3D) simulations demonstrate that supermassive stars form via rapid mass accretion, those resolving the stellar interior have been limited. Here, we report 3D radiation-hydrodynamic (RHD) simulations following the evolution of rapidly accreting protostars resolving the stellar interior. We use an adaptive mesh refinement code with our newly developed RHD solver employing an explicit M1 closure method. We follow the early evolution until the stellar mass reaches ~ 10 M_⊙fromtwodifferentinitialconfigurationsofsphericalandturbulentclouds.Wedemonstratethat,inbothcases,aswollenprotostarwhoseradiusis100- 1000R_⊙appears,aspredictedbythestellarevolutioncalculations.ItseffectivetemperatureremainsafewthousandKelvin,andtheradiativefeedbackbyionizingphotonsistooweaktodisturbtheaccretionflowuptotheepochexaminedinthiswork.Intheturbulentcase,theprotostarrotatesrapidlyatmorethan0.4timestheKeplerianvelocityowingtotheangularmomentumprovidedbytheinitialturbulence.Theprotostarapproximatesanoblatespheroid,anditsequatorialradiusismorethantwicethepolarradius.Ourresultssuggestthatweneedtoconsidertherapidstellarrotationtoelucidatetherealistic3Dprotostellarevolutioninthesupermassivestarformation.