JWST’s PEARLS: A <i>z</i> ≃ 6 quasar in a train-wreck galaxy merger system

We present JWST NIRSpec integral field spectroscopy observations of the z = 5.89 quasar NDWFS J1425+3254 from 0.6–5.3 μm, covering the rest-frame ultraviolet and optical at a spectral resolution of R ∼ 100. The quasar has a black hole mass of M BH = (1.4 +3.1 −1.0 ) × 10 9 M ⊙ and an Eddington ratio of L Bol / L Edd = 0.3 +0.6 −0.2 , as implied from the broad Balmer H α and H β lines. The quasar host has significant ongoing obscured star formation, as well as a quasar-driven outflow with velocity 6050 +460 −630 km s −1 and ionised outflow rate of 1650 +130 −1230 M ⊙ yr −1 . This is possibly one of the most extreme outflows in the early Universe. The data also reveal that two companion galaxies are merging with the quasar host. The north-eastern companion galaxy is relatively old and very massive, with a luminosity-weighted stellar age of 65 +9 −4 Myr, stellar mass of (3.6 +0.6 −0.3 #x00D7; 10 11 M ⊙ , and star-formation rate (SFR) of ∼15–30 M ⊙ yr −1 . A bridge of gas connects this companion galaxy and the host, confirming their ongoing interaction. A second merger is occurring between the quasar host and a much younger companion galaxy to the south, with a stellar age of 6.7 ± 1.8 Myr, stellar mass of (1.9 ± 0.4)×10 10 M ⊙ , and SFR of ∼40–65 M ⊙ yr −1 . There is also another galaxy in the field, likely in the foreground at z = 1.135, which could be gravitationally lensing the quasar with a magnification of 1 &lt; μ &lt; 2 and, thus, &lt; 0.75 mag. Overall, the system is a ‘train-wreck’ merger of three galaxies, with star formation and extreme quasar activity that were likely triggered by these ongoing interactions.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-09-04
DOI
https://doi.org/10.1051/0004-6361/202554307
Primary Topic
Astronomy and Astrophysical Research
Type
article
Field-Weighted Citation Impact
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article

JWST’s PEARLS: A z ≃ 6 quasar in a train-wreck galaxy merger system

Jeremy Lim, Jake Summers, G. G. Fazio, Massimo Ricotti et al.
Astronomy and Astrophysics
Astronomy and Astrophysical Research
article

JWST’s PEARLS: A z ≃ 6 quasar in a train-wreck galaxy merger system

Jeremy Lim, Jake Summers, G. G. Fazio, Massimo Ricotti, J. Stuart B. Wyithe, Michele Perna, Rogier A. Windhorst, Rolf A. Jansen, Norman A. Grogin, Nathan Adams, Russell E. Ryan, Rachel Honor, Timothy Carleton, Madeline A. Marshall, Christopher J. Conselice, Chris J. Willott, Seth H. Cohen, Anton M. Koekemoer, J. C. J. D'Silva, Dan Coe, Simon P. Driver, S. P. Willner, Haojing Yan, Brenda Frye, Jan Scholtz, Hannah Übler, Cheng Cheng, Giovanni Ferrami, Nor Pirzkal, M. Polletta, Christopher N. A. Willmer, William C. Keel, Adi Zitrin, J. M. Diego, A. S. G. Robotham, M. Mechtley, Rafael Ortiz, Gareth C Jones
article en

Abstract

We present JWST NIRSpec integral field spectroscopy observations of the z = 5.89 quasar NDWFS J1425+3254 from 0.6–5.3 μm, covering the rest-frame ultraviolet and optical at a spectral resolution of R ∼ 100. The quasar has a black hole mass of M BH = (1.4 +3.1 −1.0 ) × 10 9 M ⊙ and an Eddington ratio of L Bol / L Edd = 0.3 +0.6 −0.2 , as implied from the broad Balmer H α and H β lines. The quasar host has significant ongoing obscured star formation, as well as a quasar-driven outflow with velocity 6050 +460 −630 km s −1 and ionised outflow rate of 1650 +130 −1230 M ⊙ yr −1 . This is possibly one of the most extreme outflows in the early Universe. The data also reveal that two companion galaxies are merging with the quasar host. The north-eastern companion galaxy is relatively old and very massive, with a luminosity-weighted stellar age of 65 +9 −4 Myr, stellar mass of (3.6 +0.6 −0.3 #x00D7; 10 11 M ⊙ , and star-formation rate (SFR) of ∼15–30 M ⊙ yr −1 . A bridge of gas connects this companion galaxy and the host, confirming their ongoing interaction. A second merger is occurring between the quasar host and a much younger companion galaxy to the south, with a stellar age of 6.7 ± 1.8 Myr, stellar mass of (1.9 ± 0.4)×10 10 M ⊙ , and SFR of ∼40–65 M ⊙ yr −1 . There is also another galaxy in the field, likely in the foreground at z = 1.135, which could be gravitationally lensing the quasar with a magnification of 1 &lt; μ &lt; 2 and, thus, &lt; 0.75 mag. Overall, the system is a ‘train-wreck’ merger of three galaxies, with star formation and extreme quasar activity that were likely triggered by these ongoing interactions.

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