| 1. |
- Surace, Marco, et al.
(författare)
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On the Detection of Supermassive Primordial Stars
- 2018
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 869:2
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Tidskriftsartikel (refereegranskat)abstract
- The collapse of supermassive primordial stars in hot, atomically cooled halos may have given birth to the first quasars at z similar to 15-20. Recent numerical simulations of these rapidly accreting stars reveal that they are cool, red hypergiants shrouded by dense envelopes of pristine atomically cooled gas at 6000-8000 K, with luminosities L greater than or similar to 10(10) L-circle dot. Could such luminous but cool objects be detected as the first stage of quasar formation in future near-infrared (NIR) surveys? We have now calculated the spectra of supermassive primordial stars in their birth envelopes with the Cloudy code. We find that some of these stars will be visible to the James Webb Space Telescope at z less than or similar to 20 and that with modest gravitational lensing, Euclid and the Wide-Field Infrared Space Telescope could detect them out to z similar to 10-12. Rather than obscuring the star, its accretion envelope enhances its visibility in the NIR today by reprocessing its short-wavelength flux into photons that are just redward of the Lyman limit in the rest frame of the star.
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| 2. |
- Surace, Marco, et al.
(författare)
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On the detection of supermassive primordial stars - II. Blue supergiants
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 488:3, s. 3995-4003
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Tidskriftsartikel (refereegranskat)abstract
- Supermassive primordial stars in hot, atomically cooling haloes at z similar to 15-20 may have given birth to the first quasars in the Universe. Most simulations of these rapidly accreting stars suggest that they are red, cool hypergiants, but more recent models indicate that some may have been bluer and hotter, with surface temperatures of 20 000-40 000 K. These stars have spectral features that are quite distinct from those of cooler stars and may have different detection limits in the near-infrared today. Here, we present spectra and AB magnitudes for hot, blue supermassive primordial stars calculated with the MUSTY and CLOUDY codes. We find that photometric detections of these stars by the James Webb Space Telescope will be limited to z less than or similar to 10-12, lower redshifts than those at which red stars can be found, because of quenching by their accretion envelopes. With moderate gravitational lensing, Euclid and the Wide-Field Infrared Space Telescope could detect blue supermassive stars out to similar redshifts in wide-field surveys.
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| 3. |
- Whalen, Daniel J., et al.
(författare)
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Finding Direct-collapse Black Holes at Birth
- 2020
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 897:1
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Tidskriftsartikel (refereegranskat)abstract
- Direct-collapse black holes (DCBHs) are currently one of the leading contenders for the origins of the first quasars in the universe, over 300 of which have now been found at z > 6. But the birth of a DCBH in an atomically cooling halo does not by itself guarantee it will become a quasar by z similar to 7, the halo must also be located in cold accretion flows or later merge with a series of other gas-rich halos capable of fueling the BH's rapid growth. Here, we present near-infrared luminosities for DCBHs born in cold accretion flows in which they are destined to grow to 10(9) M-circle dot by z similar to 7. Our observables, which are derived from cosmological simulations with radiation hydrodynamics with Enzo, reveal that DCBHs could be found by the James Webb Space Telescope at z less than or similar to 20 and strongly lensed DCBHs might be found in future wide-field surveys by Euclid and the Wide-Field Infrared Space Telescope at z less than or similar to 15.
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