SIMBAD references

The peculiar emission properties of the z ∼ 6.6 Lyα emitter COSMOS redshift 7 (CR7) have been initially interpreted with the presence of either a direct collapse black hole (DCBH) or a substantial mass of Pop III stars. Instead, updated photometric observations by Bowler et al. seem to suggest that CR7 is a more standard system. Here, we confirm that the original DCBH hypothesis is consistent also with the new data. Using radiation-hydrodynamic simulations, we reproduce the new infrared photometry with two models involving a Compton-thick DCBH of mass ≃7 x 10⁶ M_☉ accreting (a) metal-free (Z = 0) gas with column density N_H = 8 x 10²⁵ cm^–2 or (b) low-metallicity gas (Z = 5 x 10^–3 Z_☉) with N_H = 3 x 10²⁴ cm^–2. The best-fitting model reproduces the photometric data to within 1σ. Such metals can be produced by weak star-forming activity occurring after the formation of the DCBH. The main contribution to the Spitzer/IRAC 3.6 µm photometric band in both models is due to He I/He II λλ4714, 4687 emission lines, while the contribution of [O III] λλ4959, 5007 emission lines, if present, is sub-dominant. Spectroscopic observations with JWST will be required to ultimately clarify the nature of CR7.