1. Chandra and Magellan /FIRE follow-up observations of PSO167???13: An X-ray weak QSO at z = 6.515
- Author
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Franz E. Bauer, Chiara Mazzucchelli, Roberto Decarli, Bin Luo, Gianni Zamorani, Ohad Shemmer, Enrico Congiu, Nico Cappelluti, Thomas Connor, Eduardo Bañados, Riccardo Nanni, Andrea Comastri, M. Mignoli, Simona Gallerani, Federica Ricci, Francesco Calura, Marcella Brusa, Francesca Civano, Fabio Vito, Roberto Gilli, W. N. Brandt, Cristian Vignali, Vito, F., Brandt, W. N., Ricci, F., Congiu, E., Connor, T., Ba??ados, E., Bauer, F. E., Gilli, R., Luo, B., Mazzucchelli, C., Mignoli, M., Shemmer, O., Vignali, C., Calura, F., Comastri, A., Decarli, R., Gallerani, S., Nanni, R., Brusa, M., Cappelluti, N., Civano, F., Zamorani, G., Banados, E., Brandt, W.N., Bañados, E., and Bauer, F.E.
- Subjects
QSOS ,media_common.quotation_subject ,astro-ph.GA ,observational [methods] ,FOS: Physical sciences ,Individual: J167.6415-134960 [Galaxies] ,Astrophysics ,01 natural sciences ,Luminosity ,6415-134960 ,Settore FIS/05 - Astronomia e Astrofisica ,individual: J167 [galaxies] ,0103 physical sciences ,Emission spectrum ,010303 astronomy & astrophysics ,media_common ,Physics ,010308 nuclear & particles physics ,early Universe / galaxies: active / galaxies: high-redshift / methods: observational / galaxies: individual: J167.6415-134960 / X-rays: individuals: J167.6415-134960 ,Astronomy and Astrophysics ,Individuals: J167.6415-134960 [X-rays] ,early Universe ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Universe ,Redshift ,Blueshift ,Space and Planetary Science ,Sky ,Astrophysics of Galaxies (astro-ph.GA) ,active [galaxies] ,individuals: J167 [X-rays] ,high-redshift [galaxies] - Abstract
The discovery of hundreds of QSOs in the first Gyr of the Universe powered by already grown SMBHs challenges our knowledge of SMBH formation. In particular, investigations of $z>6$ QSOs presenting notable properties can provide unique information on the physics of fast SMBH growth in the early universe. We present the results of follow-up observations of the $z=6.515$ radio-quiet QSO PSO167-13, which is interacting with a close companion galaxy. The PSO167-13 system has been recently proposed to host the first heavily obscured X-ray source at high redshift. We observed PSO167-13 with Chandra/ACIS-S (177 ks), and obtained new spectroscopic observations (7.2 h) with Magellan/FIRE. No significant X-ray emission is detected from the PSO167-13 system, suggesting that the obscured X-ray source previously tentatively detected was either due to a strong background fluctuation or is highly variable. The upper limit (90% confidence level) on the X-ray emission of PSO167-13 ($L_{2-10\,\mathrm{keV}}6$ QSO. The ratio between the X-ray and UV luminosity of $\alpha_{ox}6$ times weaker than the expectation based on its UV luminosity. The new Magellan/FIRE spectrum of PSO167-13 is strongly affected by the unfavorable sky conditions, but the tentatively detected C IV and Mg II emission lines appear strongly blueshifted. The most plausible explanations for the X-ray weakness of PSO167-13 are intrinsic weakness or small-scale absorption by Compton-thick material. The possible strong blueshift of its emission lines hints at the presence of nuclear winds, which could be related to its X-ray weakness., Comment: Accepted for publication on A&A
- Published
- 2021