شبه النجوم: شرانق بداخلها ثقب أسود سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2603.21714

The recently discovered Little Red Dots identified by the James Webb Space Telescope are compact high-redshift sources whose properties have motivated models involving black holes embedded within optically thick gaseous envelopes. We investigate their rest-frame optical emission by modeling quasi-stars, i.e. stellar envelopes powered by accretion onto a central black hole, formed from rapidly accreting proto-stars that reach the supermassive star regime ($$>10^4$$~\Msun) before undergoing general relativistic instability. We compute stellar evolution models with mass gain rates of 0.01, 0.1, and 1~\Msun/yr and metallicities $$Z=0$$-$$0.01$$. For accretion rates $$\ge0.1$$~\Msun/yr, stars remain nearly fully convective with $$T_\mathrm{eff}\sim4000$$-$$9000$$~K. General relativistic instability occurs at $$M_\star\sim3.5\times10^4$$~\Msun\ ($$6.8\times10^4$$~\Msun) for $$\dot{m}=0.1$$~\Msun/yr (1~\Msun/yr), at $$L\sim10^9$$~\Lsun. Assuming the black hole supports the envelope until complete accretion ($$M_{\rm BH,max}/M_{\rm QS}=1$$), quasi-stars reach maximum lifetimes of $$10^7$$-$$10^8$$~yr, $$\sim100$$-$$1000$$ times longer than their progenitors. Their formation and evolution are nearly independent of metallicity. Matching our models to Little Red Dots at $$z<4.5$$ ($$L_\mathrm{bol}\sim10^{9.5}$$-$$10^{11.5}$$~\Lsun) implies quasi-star masses of $$10^{4.5}$$-$$10^{6.5}$$~\Msun, while the minimum observed luminosity requires progenitor accretion rates $$\gtrsim0.1$$~\Msun/yr. Our models support quasi-stars as the origin of Little Red Dot optical emission and constrain their masses, lifetimes, progenitor environments, and luminosities. Our models offer a framework supporting quasi-stars as the source of Little Red Dot optical emission, and provide insights into their lifetimes, composition, progenitor's environment as well on their minimum and maximum observed luminosities.