The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524

R. Nanni, R. Gilli, C. Vignali, M. Mignoli, A. Comastri, E. Vanzella, G. Zamorani, F. Calura, G. Lanzuisi, M. Brusa, P. Tozzi, K. Iwasawa, M. Cappi, F. Vito, B. Balmaverde, T. Costa, G. Risaliti, M. Paolillo, I. Prandoni, E. LiuzzoP. Rosati, M. Chiaberge, G. B. Caminha, E. Sani, Nico Cappelluti, C. Norman

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We present the results from a ∼ 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. This is the deepest X-ray observation to date of a z ∼ 6 QSO. The QSO is detected with a total of 125 net counts in the full (0.500A0-7 keV) band and its spectrum can be modeled by a single power-law model with photon index of Γ = 1.81 ± 0.18 and full band flux of f = 3.95 × 10-15 erg s-1 cm-2. When compared with the data obtained by XMM-Newton in 2003, our Chandra observation in 2017 shows a harder (ΔΓ ≈-0.6) spectrum and a 2.5 times fainter flux. Such a variation, in a timespan of ∼ 2 yr rest-frame, is unexpected for such a luminous QSO powered by a > 109M· black hole. The observed source hardening and weakening could be related to an intrinsic variation in the accretion rate. However, the limited photon statistics does not allow us to discriminate between an intrinsic luminosity and spectral change, and an absorption event produced by an intervening gas cloud along the line of sight. We also report the discovery of diffuse X-ray emission that extends for 30″ × 20″ southward of the QSO with a signal-to-noise ratio (S/N) of approximately six, hardness ratio of HR = 0.03+0.20 -0.25, and soft band flux of f0.5-keV = 1.1+0.3 -0.3 × 10-15 erg s-1 cm-2, that is not associated to a group or cluster of galaxies. We discuss two possible explanations for the extended emission, which may be either associated with the radio lobe of a nearby, foreground radio galaxy (at z ≈ 1-2), or ascribed to the feedback from the QSO itself acting on its surrounding environment, as proposed by simulations of early black hole formation.

Original languageEnglish (US)
Article numberA121
JournalAstronomy and Astrophysics
Volume614
DOIs
StatePublished - Jun 1 2018
Externally publishedYes

Fingerprint

erg
quasars
radio
hardening
signal-to-noise ratio
hardness
power law
accretion
gas
simulation
radio galaxies
photons
XMM-Newton telescope
lobes
newton
line of sight
signal to noise ratios
x rays
luminosity
statistics

Keywords

  • Galaxies: active
  • Galaxies: high-redshift
  • Quasars: general
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Nanni, R., Gilli, R., Vignali, C., Mignoli, M., Comastri, A., Vanzella, E., ... Norman, C. (2018). The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. Astronomy and Astrophysics, 614, [A121]. https://doi.org/10.1051/0004-6361/201832694

The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. / Nanni, R.; Gilli, R.; Vignali, C.; Mignoli, M.; Comastri, A.; Vanzella, E.; Zamorani, G.; Calura, F.; Lanzuisi, G.; Brusa, M.; Tozzi, P.; Iwasawa, K.; Cappi, M.; Vito, F.; Balmaverde, B.; Costa, T.; Risaliti, G.; Paolillo, M.; Prandoni, I.; Liuzzo, E.; Rosati, P.; Chiaberge, M.; Caminha, G. B.; Sani, E.; Cappelluti, Nico; Norman, C.

In: Astronomy and Astrophysics, Vol. 614, A121, 01.06.2018.

Research output: Contribution to journalArticle

Nanni, R, Gilli, R, Vignali, C, Mignoli, M, Comastri, A, Vanzella, E, Zamorani, G, Calura, F, Lanzuisi, G, Brusa, M, Tozzi, P, Iwasawa, K, Cappi, M, Vito, F, Balmaverde, B, Costa, T, Risaliti, G, Paolillo, M, Prandoni, I, Liuzzo, E, Rosati, P, Chiaberge, M, Caminha, GB, Sani, E, Cappelluti, N & Norman, C 2018, 'The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524', Astronomy and Astrophysics, vol. 614, A121. https://doi.org/10.1051/0004-6361/201832694
Nanni R, Gilli R, Vignali C, Mignoli M, Comastri A, Vanzella E et al. The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. Astronomy and Astrophysics. 2018 Jun 1;614. A121. https://doi.org/10.1051/0004-6361/201832694
Nanni, R. ; Gilli, R. ; Vignali, C. ; Mignoli, M. ; Comastri, A. ; Vanzella, E. ; Zamorani, G. ; Calura, F. ; Lanzuisi, G. ; Brusa, M. ; Tozzi, P. ; Iwasawa, K. ; Cappi, M. ; Vito, F. ; Balmaverde, B. ; Costa, T. ; Risaliti, G. ; Paolillo, M. ; Prandoni, I. ; Liuzzo, E. ; Rosati, P. ; Chiaberge, M. ; Caminha, G. B. ; Sani, E. ; Cappelluti, Nico ; Norman, C. / The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. In: Astronomy and Astrophysics. 2018 ; Vol. 614.
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AU - Nanni, R.

AU - Gilli, R.

AU - Vignali, C.

AU - Mignoli, M.

AU - Comastri, A.

AU - Vanzella, E.

AU - Zamorani, G.

AU - Calura, F.

AU - Lanzuisi, G.

AU - Brusa, M.

AU - Tozzi, P.

AU - Iwasawa, K.

AU - Cappi, M.

AU - Vito, F.

AU - Balmaverde, B.

AU - Costa, T.

AU - Risaliti, G.

AU - Paolillo, M.

AU - Prandoni, I.

AU - Liuzzo, E.

AU - Rosati, P.

AU - Chiaberge, M.

AU - Caminha, G. B.

AU - Sani, E.

AU - Cappelluti, Nico

AU - Norman, C.

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N2 - We present the results from a ∼ 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. This is the deepest X-ray observation to date of a z ∼ 6 QSO. The QSO is detected with a total of 125 net counts in the full (0.500A0-7 keV) band and its spectrum can be modeled by a single power-law model with photon index of Γ = 1.81 ± 0.18 and full band flux of f = 3.95 × 10-15 erg s-1 cm-2. When compared with the data obtained by XMM-Newton in 2003, our Chandra observation in 2017 shows a harder (ΔΓ ≈-0.6) spectrum and a 2.5 times fainter flux. Such a variation, in a timespan of ∼ 2 yr rest-frame, is unexpected for such a luminous QSO powered by a > 109M· black hole. The observed source hardening and weakening could be related to an intrinsic variation in the accretion rate. However, the limited photon statistics does not allow us to discriminate between an intrinsic luminosity and spectral change, and an absorption event produced by an intervening gas cloud along the line of sight. We also report the discovery of diffuse X-ray emission that extends for 30″ × 20″ southward of the QSO with a signal-to-noise ratio (S/N) of approximately six, hardness ratio of HR = 0.03+0.20 -0.25, and soft band flux of f0.5-keV = 1.1+0.3 -0.3 × 10-15 erg s-1 cm-2, that is not associated to a group or cluster of galaxies. We discuss two possible explanations for the extended emission, which may be either associated with the radio lobe of a nearby, foreground radio galaxy (at z ≈ 1-2), or ascribed to the feedback from the QSO itself acting on its surrounding environment, as proposed by simulations of early black hole formation.

AB - We present the results from a ∼ 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030 + 0524. This is the deepest X-ray observation to date of a z ∼ 6 QSO. The QSO is detected with a total of 125 net counts in the full (0.500A0-7 keV) band and its spectrum can be modeled by a single power-law model with photon index of Γ = 1.81 ± 0.18 and full band flux of f = 3.95 × 10-15 erg s-1 cm-2. When compared with the data obtained by XMM-Newton in 2003, our Chandra observation in 2017 shows a harder (ΔΓ ≈-0.6) spectrum and a 2.5 times fainter flux. Such a variation, in a timespan of ∼ 2 yr rest-frame, is unexpected for such a luminous QSO powered by a > 109M· black hole. The observed source hardening and weakening could be related to an intrinsic variation in the accretion rate. However, the limited photon statistics does not allow us to discriminate between an intrinsic luminosity and spectral change, and an absorption event produced by an intervening gas cloud along the line of sight. We also report the discovery of diffuse X-ray emission that extends for 30″ × 20″ southward of the QSO with a signal-to-noise ratio (S/N) of approximately six, hardness ratio of HR = 0.03+0.20 -0.25, and soft band flux of f0.5-keV = 1.1+0.3 -0.3 × 10-15 erg s-1 cm-2, that is not associated to a group or cluster of galaxies. We discuss two possible explanations for the extended emission, which may be either associated with the radio lobe of a nearby, foreground radio galaxy (at z ≈ 1-2), or ascribed to the feedback from the QSO itself acting on its surrounding environment, as proposed by simulations of early black hole formation.

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