Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/35375
Title: | HYPerluminous quasars at the Epoch of ReionizatION (HYPERION). A new regime for the X-ray nuclear properties of the first quasars | Authors: | ZAPPACOSTA, Luca PICONCELLI, Enrico FIORE, Fabrizio Saccheo, I. VALIANTE, Rosa Vignali, C. Vito, F. Volonteri, M. BISCHETTI, Manuela COMASTRI, Andrea Done, C. Elvis, M. GIALLONGO, Emanuele La Franca, F. LANZUISI, Giorgio Laurenti, M. Miniutti, G. BONGIORNO, Angela Brusa, M. Civano, F. Carniani, S. D'ODORICO, Valentina FERUGLIO, Chiara Gallerani, S. GILLI, Roberto GRAZIAN, Andrea Guainazzi, M. Marinucci, A. MENCI, Nicola Middei, R. NICASTRO, Fabrizio Puccetti, S. TOMBESI, Francesco TORTOSA, Alessia TESTA, Vincenzo VIETRI, Giustina CRISTIANI, Stefano Haardt, F. Maiolino, R. Schneider, R. Tripodi, R. Vallini, L. VANZELLA, Eros |
Issue Date: | 2023 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 678 | First Page: | A201 | Abstract: | The existence of luminous quasars (QSO) at the Epoch of Reionization (EoR; i.e. z>6) powered by supermassive black holes (SMBH) with masses $\gtrsim10^9~M_\odot$ challenges models of early SMBH formation. To shed light on the nature of these sources we started a multiwavelength programme based on a sample of 18 HYPerluminous quasars at the Epoch of ReionizatION (HYPERION). These are the luminous QSOs whose SMBH must have had the fastest mass growth during the Universe first Gyr. In this paper we present the HYPERION sample and report on the first of the 3 years planned observations of the 2.4 Ms XMM-Newton Multi-Year Heritage program on which HYPERION is based. The goal of this program is to accurately characterize the X-ray nuclear properties of QSOs at the EoR. Through a joint X-ray spectral analysis of 10 sources, in the rest-frame $\sim2-50$ keV range, we report a steep average photon index ($\Gamma\sim2.4\pm0.1$). Absorption is not required. The average $\Gamma$ is inconsistent at $\geq4\sigma$ level with the canonical 1.8-2 value measured in QSO at z<6. This spectral slope is also much steeper than that reported in lower-z QSOs with similar luminosity or accretion rate, thus suggesting a genuine redshift evolution. Alternatively, we can interpret this result as the presence of an unusually low-energy cutoff $E_{cut}\sim20$ keV on a standard $\Gamma=1.9$ power-law. We also report on mild indications that HYPERION QSOs show higher soft X-ray emission at 2 keV compared to the UV one at 2500A than expected by lower-z luminous AGN. We speculate that a redshift-dependent coupling between the corona and accretion disc or intrinsically different coronal properties may account for the steep spectral slopes, especially in the presence of powerful winds. The reported slopes, if confirmed at lower luminosities, may have an important impact on future X-ray AGN studies in the early Universe. | URI: | http://hdl.handle.net/20.500.12386/35375 | URL: | https://www.aanda.org/articles/aa/full_html/2023/10/aa46795-23/aa46795-23.html http://arxiv.org/abs/2305.02347v2 |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/202346795 | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
zappacosta2023.pdf | Pdf editoriale | 2.36 MB | Adobe PDF | View/Open |
Page view(s)
25
checked on Dec 5, 2024
Download(s)
10
checked on Dec 5, 2024
Google ScholarTM
Check
Altmetric
Altmetric
Items in DSpace are published in Open Access, unless otherwise indicated.