QSOFEED: Investigating warm molecular, low- and high-ionization atomic gas in six type-2 quasars with GTC/EMIR

¹ Instituto de Astrofísica de Canarias, Calle Vía Láctea, s/n, 38205 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
³ Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125 (Torino), Italy
⁴ INAF – Osservatorio Astrofisico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy
⁵ European Southern Observatory (ESO), Alonso de Córdova 3107, Casilla 19, Santiago 19001, Chile
⁶ Instituto de Física Fundamental, CSIC, Calle Serrano 123, 28006 Madrid, Spain
⁷ Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, United Kingdom
⁸ School of Mathematical and Physical Science, University of Sheffield, Sheffield S3 7RH, UK
⁹ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy

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Received: 22 October 2025
Accepted: 29 January 2026

Abstract

We present long-slit near-infrared spectroscopic observations of six nearby (z ∼ 0.1) radio-quiet type-2 quasars (QSO2s) from the Quasar Feedback (QSOFEED) sample. The QSO2s have bolometric luminosities of 10^{45 − 46} erg s⁻¹ and stellar masses of 10^10.6−11.3 M_⊙. The observations were obtained with the instrument Espectrógrafo Multiobjeto Infra-Rojo (EMIR) at the 10.4 m Gran Telescopio Canarias. The nuclear K-band spectra (central ∼1–3 kpc of the QSO2s) reveal signatures of high-velocity outflows in either the Paα or Brγ lines, depending on the redshift, and in the [Si VI] lines. The broadest kinematic components have a full width at half maximum (FWHM) of ∼1200–2500 km s⁻¹. From the near-infrared hydrogen recombination lines, we derived ionized outflow masses of M_Hion ∼ 0.08−20 × 10⁶ M_⊙, mass outflow rates of Ṁ_Hion ∼ 0.03−6 M_⊙ yr⁻¹, and kinetic powers of Ė_Hion ∼ 10^37.8−40.8 erg s⁻¹. These ionized gas outflow masses and mass outflow rates have median values that are 5.9 and 5.8 times larger, respectively, than those derived from the [Si VI] line. Our study provides evidence, at least for these six QSO2s, that the near-infrared recombination lines and [Si VI] trace the same outflow (i.e., they have similar kinematics and radii), but they carry different amounts of mass. We detected warm molecular lines in the six QSO2s, from which we measured total (nuclear) gas masses from 1.1 (0.7) to 32 (13) × 10³ M_⊙, similar to other QSO2s with warm H₂ measurements reported in the literature, but we did not find any molecular outflow associated with them. Based on comparison with five other QSO2s with H₂ measurements reported in the literature, we find that the four QSO2s with detected H₂ outflows have total (nuclear) H₂ masses that are 2.2 (2.7) times larger, on average, than the seven QSO2s without detected H₂ outflows.