Supermassive Dark Stars: Detectable in JWST (1002.2233v1)

Abstract: The first phase of stellar evolution in the history of the Universe may be Dark Stars, powered by dark matter heating rather than by nuclear fusion. Weakly Interacting Massive Particles, which may be their own antipartners, collect inside the first stars and annihilate to produce a heat source that can power the stars for millions to billions of years. In this paper we show that these objects can grow to be supermassive dark stars (SMDS) with masses $\gtrsim (10^5-10^7) \msun$. The growth continues as long as dark matter heating persists, since dark stars are large and cool (surface temperature $\lesssim 5\times 10^4$K) and do not emit enough ionizing photons to prevent further accretion of baryons onto the star. The dark matter may be provided by two mechanisms: (1) gravitational attraction of dark matter particles on a variety of orbits not previously considered, and (2) capture of WIMPs due to elastic scattering. Once the dark matter fuel is exhausted, the SMDS becomes a heavy main sequence star; these stars eventually collapse to form massive black holes that may provide seeds for supermassive black holes in the Universe. SMDS are very bright, with luminosities exceeding $(10^9-10^{11}) L_\odot$. We demonstrate that for several reasonable parameters, these objects will be detectable with JWST. Such an observational discovery would confirm the existence of a new phase of stellar evolution powered by dark matter.

• The paper demonstrates that dark matter heating via WIMP annihilation can sustain supermassive stars with masses from 10^5 to 10^7 solar masses.
• It introduces two mechanisms—extended adiabatic contraction and dark matter capture—to model sustained baryonic accretion in early stellar evolution.
• Observational predictions indicate that these stars, with luminosities up to 10^11 L⊙ and extended lifetimes, are detectable by JWST, offering new insights into cosmic structure.

Overview of the Supermassive Dark Stars Research

The paper "Supermassive Dark Stars: Detectable in JWST" by Katherine Freese et al. explores a novel phase of stellar evolution driven by dark matter, proposing the existence of Supermassive Dark Stars (SMDS) whose formations could be observed by the James Webb Space Telescope (JWST). These hypothetical stars are argued to be powered not by nuclear fusion but by the heating mechanisms provided by the annihilation of Weakly Interacting Massive Particles (WIMPs), a candidate for dark matter which could be its own antiparticle. Such stars could grow to substantial masses, between $10^5$ and $10^7$ solar masses, during their evolutionary periods by consistently accreting baryons while maintained by dark matter heating.

Theoretical Background and Model Construction

The paper expands on earlier work by Spolyar et al., presenting two mechanisms through which dark matter could sustain SMDS. The first mechanism, extended adiabatic contraction, posits that dark matter is accumulated through gravitational attraction of baryonic material within the star. The second mechanism involves extended capture, where WIMPs from the surrounding halo are captured by the stars due to scattering events. These processes are modeled alongside detailed calculations of stellar evolution from initial formation through the accretion of baryonic clouds to massive SMDS variants.

Numerical Findings and Implications

The authors establish that SMDS can sustain lifetimes significantly exceeding those of traditional fusion stars, not exhausting their dark matter sources for millions to potentially billions of years. With effective surface temperatures around $5 \times 10^4$ K, these stars remain cool, which permits continuous baryon accretion without the feedback restrictions seen in standard Population III stars. Importantly, the SMDS could evolve into objects with profound luminosities ranging from $(10^9-10^{11}) L_\odot$, rendering them detectable by JWST.

Observational Potential and Cosmic Role

A key conclusion of the paper is the potential observational detectability of these SMDS by JWST, which opens promising avenues for empirical validation of this theoretical framework. Observing these entities would not only confirm a new evolutionary stage in stellar life cycles but could also elucidate the role of dark matter during cosmic structure formation epochs.

Furthermore, the SMDS might address unresolved phenomena such as providing seed black holes for subsequent supermassive black holes observed in high-redshift quasars or contributing to the growth of black holes observed today. This alignment with observational cosmology could substantially reshape our understanding of early universe structures and the role WIMP dark matter plays.

Future Prospects and Speculations

The outlined mechanisms and potential for JWST observation present future research directions that could explore the precise conditions under which SMDS might form and evolve. High-resolution simulations and detailed cosmological models will be essential to further understand the dynamic interactions between dark matter and baryonic substances in early halo environments. Should observational evidence support these hypotheses, it would necessitate a revision of the mass and luminosity functions of stars in early cosmic timelines, profoundly impacting theories concerning dark matter distributions and densities.

In conclusion, this research presents a compelling narrative for dark matter's role in stellar evolution, proposing a phenomenological framework that integrates that new phase within the cosmic development landscape. It invites further theoretical and observational scrutiny to validate and potentially redefine star formation paradigms.