X-Ray Observations of a [C ii]-bright, z = 6.59 Quasar/Companion System

Connor, Thomas; Bañados, Eduardo; Mazzucchelli, Chiara; Stern, Daniel; Decarli, Roberto; Fan, Xiaohui; Farina, Emanuele Paolo; Lusso, Elisabeta; Neeleman, Marcel; Walter, Fabian

doi:10.3847/1538-4357/abaab9

Cited by 31 publications

(30 citation statements)

References 79 publications

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“…Assuming that this emission is not driven by a source with an extreme power-law spectral index (Γ  5), PJ352−15 is not host to the most X-ray luminous jets in the z > 2 universe. In contrast, for a steeper spectral slope, the high predicted luminosity is caused by extrapolating a poorly constrained spectrum into unobserved energy ranges (e.g., Connor et al 2020) and is not indicative of an expected relation between Γ and L 2-10 . As can be seen in Figure 3, PJ352−15 is not an outlier in radio-loudness among the broad population of quasars; the only reason we would expect this emission to be large is due to the (1 + z) 4 scaling of the CMB energy density.…”

Section: Properties Of the Extended Emissionmentioning

confidence: 95%

“…Data reduction was performed using the Chandra Interactive Analysis of Observations software package (CIAO; Fruscione et al 2006) v4.11 with CALDB version 4.8.4.1. Reduction followed standard procedures (e.g., Connor et al 2020), beginning with reprocessing using the chandra_repro script with standard grade, status, and good time filters and with VFAINT background cleaning. As part of the standard reprocessing, events were processed with the Energy Dependent Subpixel Event Repositioning (EDSER) routine (Li et al 2004); because of this reprocessing of the on-axis observations, and to enable more detailed physical modeling, all X-ray images in this work are presented at half-pixel (0 246) resolution (and all images presented are of the combined seven observations).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Connor

Bañados

Stern

et al. 2021

ApJ

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We present deep (265 ks) Chandra X-ray observations of PSO J352.4034−15.3373, a quasar at z = 5.831 that, with a radio-to-optical flux ratio of R > 1000, is one of the radio-loudest quasars in the early universe and is the only quasar with observed extended radio jets of kiloparsec scale at z ≳ 6. Modeling the X-ray spectrum of the quasar with a power law, we find a best fit of Γ = 1.99 − 0.28 + 0.29 , leading to an X-ray luminosity of L 2 – 10 = 1.26 − 0.33 + 0.45 × 10 45 erg s − 1 and an X-ray to UV brightness ratio of α OX = −1.45 ± −0.11. We identify a diffuse structure 50 kpc (∼8″) to the NW of the quasar along the jet axis that corresponds to a 3σ enhancement in the angular density of emission and can be ruled out as a background fluctuation with a probability of P = 0.9985. While with few detected photons the spectral fit of the structure is uncertain, we find that it has a luminosity of L 2–10 ∼ 1044 erg s−1. These observations therefore potentially represent the most distant quasar jet yet seen in X-rays. We find no evidence for excess X-ray emission where the previously reported radio jets are seen (which have an overall linear extent of 0.″28), and a bright X-ray point source located along the jet axis to the SE is revealed by optical and NIR imaging to not be associated with the quasar.

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Section: Properties Of the Extended Emissionmentioning

confidence: 95%

Section: Observations and Data Reductionmentioning

confidence: 99%

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Connor

Bañados

Stern

et al. 2021

ApJ

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“…Recent deep X-ray observations of some of the above sources did not reveal potentially obscured quasars. To date, there is no strong evidence that these obscured companions of z ∼ 6 quasars are obscured AGN (Connor et al 2020;Vito et al 2021).…”

Section: Number Of Qso Pairs As a Constraint On Massive Bh Origins And Assemblymentioning

confidence: 99%

Quasar clustering at redshift 6

Greiner

Bolmer

Yates

et al. 2021

A&A

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Context. Large-scale surveys over the last years have revealed about 300 quasi-stellar objects (QSOs) at redshifts above 6. Follow-up observations have identified surprising properties, such as the very high black hole (BH) masses, spatial correlations with surrounding cold gas of the host galaxy, and high CIV-MgII Velocity shifts. In particular, the discovery of luminous high-redshift quasars suggests that at least some BHs likely have high masses at birth and grow efficiently. Aims. Our aim is to quantify quasar pairs at high redshift for a large sample of objects. This provides a new key constraint on a combination of parameters related to the origin and assembly for the most massive BHs: formation efficiency and clustering, growth efficiency, and the relative contribution of BH mergers. Methods. We observed 116 spectroscopically confirmed QSOs around redshift 6 with the simultaneous seven-channel imager Gamma-ray Burst Optical/Near-infrared Detector in order to search for companions. Applying colour-colour cuts identical to those which led to the spectroscopically confirmed QSOs, we performed Le PHARE fits to the 26 best QSO pair candidates, and obtained spectroscopic observations for 11 of them. Results. We do not find any QSO pair with a companion brighter than M1450(AB) < −26 mag within our 0.1–3.3 h−1 cMpc search radius, in contrast to the serendipitous findings in the redshift range 4–5. However, a small fraction of such pairs at this luminosity and redshift is consistent with indications from present-day cosmological-scale galaxy evolution models. In turn, the incidence of L- and T-type brown dwarfs, which occupy a similar colour space to z ∼ 6 QSOs, is higher than expected, by a factor of 5 and 20, respectively.

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“…However, studies of the X-ray properties of these systems are still limited. There are ∼ 30 quasars detected in X-rays at z > 6 (e.g., Shemmer et al 2006;Page et al 2014;Moretti et al 2014;Ai et al 2017;Gallerani et al 2017;Nanni et al 2017Nanni et al , 2018Bañados et al 2018;Vito et al 2019a;Connor et al 2019Connor et al , 2020Wang et al 2021) among more than 200 quasars known at this redshift, and only seven at z > 6.5 with X-ray detections (e.g., Page et al 2014;Vito et al 2019a;Bañados et al 2018;Connor et al 2020;Pons et al 2020;Wang et al 2021). Due to their extreme distances, the observed X-ray emission of these quasars is very faint, and only four z > 6 quasars are detected with more than 100 net counts (Page et al 2014;Ai et al 2017;Nanni et al 2017;Vito et al 2019a), which limits detailed investigations of their X-ray spectral properties and any correlations with other quasar properties.…”

Section: Introductionmentioning

confidence: 99%

Deep XMM-Newton Observations of an X-ray Weak, Broad Absorption Line Quasar at $z=6.5$

Yang,

Fan,

Wang

et al. 2021

Preprint

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We report X-ray observations of the most distant known gravitationally lensed quasar, J0439+1634 at z = 6.52, which is also a broad absorption line (BAL) quasar, using the XMM-Newton Observatory. With a 130 ks exposure, the quasar is significantly detected as a point source at the optical position with a total of 358 +19 −19 net counts using the EPIC instrument. By fitting a power-law plus Galactic absorption model to the observed spectra, we obtain a spectral slope of Γ = 1.45 +0.10 −0.09 . The derived optical-to-X-ray spectral slope α ox is −2.07 +0.01 −0.01 , suggesting that the X-ray emission of J0439+1634 is weaker by a factor of 18 than the expectation based on its 2500 Å luminosity and the average α ox vs. luminosity relationship. This is the first time that an X-ray weak BAL quasar at z > 6 has been observed spectroscopically. Its X-ray weakness is consistent with the properties of BAL quasars at lower redshift. By fitting a model including an intrinsic absorption component, we obtain intrinsic column densities of N H = 2.8 +0.7 −0.6 × 10 23 cm −2 and N H = 4.3 +1.8 −1.5 × 10 23 cm −2 , assuming a fixed Γ of 1.9 and a free Γ, respectively. The intrinsic rest-frame 2-10 keV luminosity is derived as (9.4−15.1)×10 43 erg s −1 , after correcting for lensing magnification (µ = 51.3). The absorbed power-law model fitting indicates that J0439+1634 is the highest redshift obscured quasar with a direct measurement of the absorbing column density. The intrinsic high column density absorption can reduce the X-ray luminosity by a factor of 3 − 7, which also indicates that this quasar could be a candidate of intrinsically X-ray weak quasar.

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X-Ray Observations of a [C ii]-bright, z = 6.59 Quasar/Companion System

Cited by 31 publications

References 79 publications

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe’s First Billion Years

Quasar clustering at redshift 6

Deep XMM-Newton Observations of an X-ray Weak, Broad Absorption Line Quasar at $z=6.5$

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