SHELLQs-JWST: Revealing the Spectra of Extended Emission in 12 z > 6 Quasar Host Galaxies using the JWST NIRSpec Fixed Slit

Camryn L. Phillips; Michael A. Strauss; Masafusa Onoue; Xuheng Ding; John D. Silverman; Yoshiki Matsuoka; Takuma Izumi; Junya Arita; Kentaro Aoki; Shunsuke Baba; Masatoshi Imanishi; Nobunari Kashikawa; Toshihiro Kawaguchi; Chien-Hsiu Lee; Mahoshi Sawamura; Yoshiki Toba; Feige Wang; Jinyi Yang

arXiv · 2510.22403

SHELLQs-JWST: Revealing the Spectra of Extended Emission in 12 z > 6 Quasar Host Galaxies using the JWST NIRSpec Fixed Slit

Camryn L. Phillips·Michael A. Strauss·Masafusa Onoue·Xuheng Ding·John D. Silverman·Yoshiki Matsuoka·Takuma Izumi·Junya Arita·Kentaro Aoki·Shunsuke Baba·Masatoshi Imanishi·Nobunari Kashikawa·Toshihiro Kawaguchi·Chien-Hsiu Lee·Mahoshi Sawamura·Yoshiki Toba·Feige Wang·Jinyi Yang

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Abstract

We present an analysis of the rest frame optical JWST NIRSpec Fixed Slit spectra of extended host galaxy emission in 12 quasars from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) sample at redshifts 6.0 < z < 6.4. The spatial point spread function is modeled primarily by a sum of two Gaussians as a function of wavelength and is used to fit and subtract the quasar from the 2D spectra, leaving only extended galaxy emission which we analyze. Ten of 12 systems show spatially extended line emission and five of 12 systems show an extended stellar continuum. From the extended [OIII]5008 emission line, we measure a 132 ${\pm}$ 19 km/s ionized outflow in one system and 52 ${\pm}$ 12 km/s rotation, suggesting a coherent disk, in another. From the extended narrow H${\alpha}$ emission, which we hypothesize is ionized by star-forming regions rather than the quasar, we measure star formation rates ranging from ${\sim}$ 7 to 111 M${_\odot}$/yr, the majority of which are consistent with the star-forming main sequence at z ${\approx}$ 6. The positions of our host galaxies on the log10[OIII]5008/H${\beta}$ vs. log10[NII]6584/H${\alpha}$ (R3N2) Baldwin-Phillips-Terlevich (BPT) diagram indicate ionization rates typical of AGN activity in the low-redshift universe, but are consistent with the placement of similar z ${\approx}$ 6 quasar host galaxies, suggesting that the R3N2 line ratios cannot distinguish AGN and star-formation powered line emission at high redshifts. We conclude from the consistency between our quasar host sample with z ${\sim}$ 6 galaxies that the presence of a low-luminosity AGN causes little significant change in the properties of galaxies at z ${\approx}$ 6 on 10 Myr timescales.

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Camryn L. Phillips, Michael A. Strauss, Masafusa Onoue, Xuheng Ding, John D. Silverman, Yoshiki Matsuoka, Takuma Izumi, Junya Arita, Kentaro Aoki, Shunsuke Baba, Masatoshi Imanishi, Nobunari Kashikawa, Toshihiro Kawaguchi, Chien-Hsiu Lee, Mahoshi Sawamura, Yoshiki Toba, Feige Wang, Jinyi Yang. 2025-10-25. SHELLQs-JWST: Revealing the Spectra of Extended Emission in 12 z > 6 Quasar Host Galaxies using the JWST NIRSpec Fixed Slit. https://arxiv.org/abs/2510.22403

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