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Dark Matter · Early Universe

Supermassive Dark Stars (SMDSs)

Supermassive dark stars (SMDSs) are luminous stellar objects formed in the early Universe at redshift z~10–20, made primarily of hydrogen and helium, yet powered by dark matter annihilation. Differentiating SMDSs from early galaxies containing zero metallicity stars at similar redshifts requires spectral, photometric, and morphological comparisons.

With only the Roman Space Telescope (RST), differentiation of SMDSs — particularly those formed via adiabatic contraction with M > 105 M☉ and lensed by >100× — is possible due to their distinct photometric signatures from the first galaxies. Those formed via dark matter capture can be differentiated only by image morphology: point object (SMDSs) vs. extended object (sufficiently magnified galaxies).

By additionally employing James Webb Space Telescope (JWST) spectroscopy, we can identify the HeII 1640 absorption line, a “smoking gun” for SMDS detection. Although RST doesn't cover the required wavelength band (for z>10 objects), JWST does, hence the two can be used in tandem to identify SMDSs.

The detection of SMDSs would confirm a new type of star powered by dark matter and may shed light on the origins of the supermassive black holes powering bright quasars observed at z>6.

Research Highlights

Click to enlargeFlux density spectra of Supermassive Dark Stars at various masses from 4.1 times 10 to the 4th to 10 to the 6th solar masses for DM capture and Extended Adiabatic Contraction formation channels showing HeII 1640 absorption line features in RST and JWST wavelength bands
Flux density spectra of Supermassive Dark Stars at various masses (4.1×104 – 106 M☉) for two formation channels: DM capture (left) and Extended Adiabatic Contraction (right). Top panels show full spectrum with HeII and H Lyman Break features; bottom panels zoom into RST/JWST wavelength bands highlighting the HeII 1640Å absorption line. (Zhang, Ilie & Freese 2024)

Related Papers

Detectability of Supermassive Dark Stars with the Roman Space Telescope

Zhang, S., Ilie, C., & Freese, K. (2024). ApJ, 965(2), 121. arXiv:2306.11606★ First Author