%0 Generic %1 pacucci2017nature %A Pacucci, Fabio %A Pallottini, Andrea %A Ferrara, Andrea %A Gallerani, Simona %D 2017 %K abundance black emission hole lya primordial %T The nature of the Lyman Alpha Emitter CR7: a persisting puzzle %U http://arxiv.org/abs/1702.04351 %X The peculiar emission properties of the $z 6.6$ Ly$\alpha$ emitter 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. (2016) 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 IR photometry with two models involving a Compton-thick DCBH of mass $7 10^6 \, M_ødot$ accreting (a) metal-free ($Z=0$) gas with column density $N_H = 8 10^25 \, cm^-2$, or (b) low-metallicity gas ($Z = 5 10^-3 \, Z_ødot$) with $N_H = 3 10^24 \, cm^-2$. The best fit model reproduces the photometric data to within $1 \sigma$. Such metals can be produced by weak star-forming activity occurring after the formation of the DCBH. The main contribution to the Spitzer/IRAC $3.6 \, m$ photometric band in both models is due to HeI/HeII $4714, 4687$ emission lines, while the contribution of OIII $4959, 5007$ emission lines, if present, is sub-dominant. Spectroscopic observations with JWST will be required to ultimately clarify the nature of CR7.

@misc{pacucci2017nature, abstract = {The peculiar emission properties of the $z \sim 6.6$ Ly$\alpha$ emitter 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. (2016) 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 IR photometry with two models involving a Compton-thick DCBH of mass $\approx 7 \times 10^6 \, \mathrm{M_{\odot}}$ accreting (a) metal-free ($Z=0$) gas with column density $N_H = 8 \times 10^{25} \, \mathrm{cm^{-2}}$, or (b) low-metallicity gas ($Z = 5 \times 10^{-3} \, \mathrm{Z_{\odot}}$) with $N_H = 3 \times 10^{24} \, \mathrm{cm^{-2}}$. The best fit model reproduces the photometric data to within $1 \sigma$. Such metals can be produced by weak star-forming activity occurring after the formation of the DCBH. The main contribution to the Spitzer/IRAC $3.6 \, \mathrm{\mu m}$ photometric band in both models is due to HeI/HeII $\lambda 4714, 4687$ emission lines, while the contribution of [OIII] $\lambda 4959, 5007$ emission lines, if present, is sub-dominant. Spectroscopic observations with JWST will be required to ultimately clarify the nature of CR7.}, added-at = {2017-02-16T10:08:25.000+0100}, author = {Pacucci, Fabio and Pallottini, Andrea and Ferrara, Andrea and Gallerani, Simona}, biburl = {https://www.bibsonomy.org/bibtex/2a7a71278416eb12b8d7f1cdbfe3cf41a/miki}, description = {[1702.04351] The nature of the Lyman Alpha Emitter CR7: a persisting puzzle}, interhash = {32096038c6b5a42b274a262faef200c9}, intrahash = {a7a71278416eb12b8d7f1cdbfe3cf41a}, keywords = {abundance black emission hole lya primordial}, note = {cite arxiv:1702.04351Comment: Accepted for publication in MNRAS Letters}, timestamp = {2017-02-16T10:08:25.000+0100}, title = {The nature of the Lyman Alpha Emitter CR7: a persisting puzzle}, url = {http://arxiv.org/abs/1702.04351}, year = 2017 }