Empirical Near-Infrared Spectral Templates from SPHEREx: Disentangling AGN and Host-Galaxy Emission

Abstract

SPHEREx conducts the first all-sky near-infrared spectral survey over 0.75-5.0 μm, spanning the transition from host-galaxy starlight to AGN-heated torus emission and enabling spectroscopic identification of active galactic nuclei (AGNs). We develop a data-driven framework combining weighted non-negative matrix factorization with forward modeling to learn empirical rest-frame templates from 2,777 normal galaxies and 1,064 AGNs in the North Ecliptic Pole (NEP) field. The resulting 14-component dictionary contains seven galaxy templates spanning stellar-population continua and nebular emission and seven AGN templates capturing emission lines and warm and hot torus continua, providing an additive, operational decomposition. Inferred near-infrared host fractions correlate with independent SDSS spectral and HSC imaging decompositions (at Pearson r=0.68 and r=0.59), comparable to the SDSS-HSC correlation (r=0.66) and supporting the reliability of the AGN-host separation. In the NEP deep field, the same templates recover redshifts with |z_fit−z_spec| < 0.01 for 93.0% of galaxies and 93.5% of AGNs and distinguish galaxies, narrow-line AGNs, and broad-line AGNs with 81.3% accuracy. At all-sky depth, classification retains 72.9% accuracy. The near-infrared coefficients also flag questionable DESI spectral classifications and redshifts, showing how SPHEREx complements optical spectroscopy. Learned directly from survey spectrophotometry and extending beyond the K band, this empirical dictionary fills a long-standing gap in near-to-mid-infrared templates and provides a data-driven foundation for population-scale studies of AGN activity and its connection to host galaxies across the SPHEREx all-sky survey.

Infrared spectroscopy of gas-phase hydrogenated and methylated pyrenes: From laboratory spectra to the simulated 3.4 μm emission band
Karine Demyk, Christine Joblin, Louan de Bentzmann +2
Astronomy & Astrophysics7 Oct 2026Peer-reviewedPublisher termsFull textSolar & stellar physicsCrossrefHAL
GA-NIFS: sRMS, a new method for disentangling resolved and unresolved emission in integral field spectroscopy. Application to distant quasars
Michele Perna, Santiago Arribas, Carlota Prieto-Jiménez +28
arXiv10 Oct 2026PreprintCC BY 4.0Full textGalaxiesarXiv
Characterising the O9–B1 spectral transition in the near-infrared
R. Castellanos, F. Najarro, M. Garcia +1
Astronomy & Astrophysics4 Nov 2026Peer-reviewedPublisher termsSolar & stellar physicsCrossref
Estimation of Dust Mass from Infrared Emission and Extinction of Supernova Remnants: G93.7-0.2, G109.1-1.0, G156.2+5.7, and G166.0+4.3
Zhe Zhang, Jun Li, Biwei Jiang +1
arXiv29 Aug 2026PreprintCC BY 4.0Full textGalaxiesarXiv
Estimation of Dust Mass from Infrared Emission and Extinction of Supernova Remnants: G93.7−0.2, G109.1−1.0, G156.2+5.7, and G166.0+4.3
Zhe 哲 Zhang 张, Jun 军 Li 李, Biwei 碧沩 Jiang 姜 +1
The Astrophysical Journal21 Oct 2026Peer-reviewedCC BY 4.0Full textSolar & stellar physicsCrossref

Cite

BibTeX RIS

BibTeX

@misc{ren2026empirical,
  title = {{Empirical Near-Infrared Spectral Templates from SPHEREx: Disentangling AGN and Host-Galaxy Emission}},
  author = {Wenke Ren and Hengxiao Guo and Zhenya Zheng and Minfeng Gu and Wenwen Zuo and Junxian Wang and Weida Hu and Zhen-Bo Su and Shi-Jiang Chen and Lin Long and Jiaqi Lin and Chi-Zhuo Wang},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.02167},
  eprint = {2609.02167},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.02167},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Empirical Near-Infrared Spectral Templates from SPHEREx: Disentangling AGN and Host-Galaxy Emission
AU  - Wenke Ren
AU  - Hengxiao Guo
AU  - Zhenya Zheng
AU  - Minfeng Gu
AU  - Wenwen Zuo
AU  - Junxian Wang
AU  - Weida Hu
AU  - Zhen-Bo Su
AU  - Shi-Jiang Chen
AU  - Lin Long
AU  - Jiaqi Lin
AU  - Chi-Zhuo Wang
PY  - 2026
DA  - 2026/09/02
PB  - arXiv
DO  - 10.48550/arxiv.2609.02167
UR  - https://arxiv.org/abs/2609.02167
AB  - SPHEREx conducts the first all-sky near-infrared spectral survey over 0.75-5.0 μm, spanning the transition from host-galaxy starlight to AGN-heated torus emission and enabling spectroscopic identification of active galactic nuclei (AGNs). We develop a data-driven framework combining weighted non-negative matrix factorization with forward modeling to learn empirical rest-frame templates from 2,777 normal galaxies and 1,064 AGNs in the North Ecliptic Pole (NEP) field. The resulting 14-component dictionary contains seven galaxy templates spanning stellar-population continua and nebular emission and seven AGN templates capturing emission lines and warm and hot torus continua, providing an additive, operational decomposition. Inferred near-infrared host fractions correlate with independent SDSS spectral and HSC imaging decompositions (at Pearson r=0.68 and r=0.59), comparable to the SDSS-HSC correlation (r=0.66) and supporting the reliability of the AGN-host separation. In the NEP deep field, the same templates recover redshifts with |z_fit−z_spec| < 0.01 for 93.0% of galaxies and 93.5% of AGNs and distinguish galaxies, narrow-line AGNs, and broad-line AGNs with 81.3% accuracy. At all-sky depth, classification retains 72.9% accuracy. The near-infrared coefficients also flag questionable DESI spectral classifications and redshifts, showing how SPHEREx complements optical spectroscopy. Learned directly from survey spectrophotometry and extending beyond the K band, this empirical dictionary fills a long-standing gap in near-to-mid-infrared templates and provides a data-driven foundation for population-scale studies of AGN activity and its connection to host galaxies across the SPHEREx all-sky survey.
ER  -

Abstract

Related

Cite