An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals

Carolina Andonie; David M. Alexander; Claire Greenwell; Sotiria Fotopoulou; Ryan Hickox; David J. Rosario; Carolin Villforth; Johannes Buchner; Jens Kristian Krogager; Brivael Laloux; Andrea Merloni; Mara Salvato; Ole Streicher; Wei Yan

doi:10.1093/mnras/staf624

An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals

Carolina Andonie, David M. Alexander, Claire Greenwell, Sotiria Fotopoulou, Ryan Hickox, David J. Rosario, Carolin Villforth, Johannes Buchner, Jens Kristian Krogager, Brivael Laloux, Andrea Merloni, Mara Salvato, Ole Streicher, Wei Yan

Research output: Contribution to journal › Article › peer-review

Abstract

We present the 4MOST (4-metre Multi-Object Spectroscopic Telescope) infrared (IR) AGN surv e y, the first large-scale optical spectroscopic surv e y characterizing mid-infrared (MIR) selected obscured active galactic nuclei (AGNs). The surv e y targets ≈212 000 obscured IR AGN candidates o v er ≈10 000 de g 2 down to a magnitude limit of r AB = 22 . 8 mag and will be ≈100 ×larger than an y e xisting obscured IR AGN spectroscopic sample. We select the targets using an MIR colour criterion applied to the unWISE catalogue from the WISE ( Wide-field Infrared Survey Explorer ) all-sky survey, and then apply a r −W 2 ≥5 . 9 mag cut; we demonstrate that this selection will mostly identify sources obscured by N H > 10 22 cm −2 . The surv e y complements the 4MOST X-ray surv e y, which will follow up ∼1 M eROSITA (extended ROentgen Surv e y with an Imaging Telescope Array)- selected (typically unobscured) AGN. We perform simulations to predict the quality of the spectra that we will obtain and validate our MIR-optical colour-selection method using X-ray spectral constraints and UV-to-far-IR spectral energy distribution (SED) modelling in four well-observ ed deep-sk y fields. We find that: (1) ≈80 −87 per cent of the WISE -selected targets are AGN down to r AB = 22 . 1 −22 . 8 mag of which ≈70 per cent are obscured by N H > 10 22 cm −2 , and (2) ≈80 per cent of the 4MOST IR AGN sample will remain undetected by the deepest eROSITA observations due to extreme absorption. Our SED- fitting results show that the 4MOST IR AGN surv e y will primarily identify obscured AGN and quasars ( ≈55 per cent of the sample is expected to have L AGN , IR > 10 45 erg s −1 ) residing in massive galaxies ( M _ ≈10 10 −10 12 M _) at z ≈0 . 5 −3 . 5 with ≈33 per cent expected to be hosted by starburst galaxies.

Original language	English
Pages (from-to)	2202-2229
Number of pages	28
Journal	Monthly Notices of the Royal Astronomical Society
Volume	539
Issue number	3
Early online date	17 Apr 2025
DOIs	https://doi.org/10.1093/mnras/staf624
Publication status	Published - 31 May 2025

Data Availability Statement

The data sets generated and/or analysed in this study are available
from the corresponding author on reasonable request.

Acknowledgements

We thank the referee for their positive and constructive comments, which substantially improved the paper.

This research used data obtained with the Dark Energy Spectroscopic Instrument (DESI). DESI construction and operations is managed by the Lawrence Berkeley National Laboratory. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High-Energy Physics, under contract no. DE-AC02-05CH11231, and by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility under the same contract. Additional support for DESI was provided by the U.S. National Science Foundation (NSF), Division of Astronomical Sciences under contract no. AST-0950945 to the NSF’s National Optical-Infrared Astronomy Research Laboratory; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising–Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Science and Technology of Mexico (CONACYT); the Ministry of Science and Innovation of Spain (MICINN), and by the DESI Member Institutions: www.desi.lbl.gov/collaborating-institutions. The DESI collaboration is honoured to be permitted to conduct scientific research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the U.S. National Science Foundation, the U.S. Department of Energy, or any of the listed funding agencies.

Funding

This work has been supported by the EU H2020-MSCA-ITN-2019 Project 860744 ‘BiD4BESt: Big Data applications for black hole Evolution STudies’. CA is supported by the Alexander von Humboldt Foundation through a Humboldt Research Fellowship for postdoctoral researchers. DMA and CG thank the Science Technology Facilities Council (STFC) for support from the Durham consolidated grant (ST/T000244/1). DJR acknowledges the support of STFC grant NU-012097.

Keywords

infrared: galaxies
quasars: general
surveys

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1093/mnras/staf624Licence: CC BY

Cite this

Andonie, C., Alexander, D. M., Greenwell, C., Fotopoulou, S., Hickox, R., Rosario, D. J., Villforth, C., Buchner, J., Krogager, J. K., Laloux, B., Merloni, A., Salvato, M., Streicher, O., & Yan, W. (2025). An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals. Monthly Notices of the Royal Astronomical Society, 539(3), 2202-2229. https://doi.org/10.1093/mnras/staf624

Andonie, C, Alexander, DM, Greenwell, C, Fotopoulou, S, Hickox, R, Rosario, DJ, Villforth, C, Buchner, J, Krogager, JK, Laloux, B, Merloni, A, Salvato, M, Streicher, O & Yan, W 2025, 'An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals', Monthly Notices of the Royal Astronomical Society, vol. 539, no. 3, pp. 2202-2229. https://doi.org/10.1093/mnras/staf624

@article{96cca0bbe2354bb9b380b26344d5c493,

title = "An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals",

abstract = "We present the 4MOST (4-metre Multi-Object Spectroscopic Telescope) infrared (IR) AGN surv e y, the first large-scale optical spectroscopic surv e y characterizing mid-infrared (MIR) selected obscured active galactic nuclei (AGNs). The surv e y targets ≈212 000 obscured IR AGN candidates o v er ≈10 000 de g 2 down to a magnitude limit of r AB = 22 . 8 mag and will be ≈100 ×larger than an y e xisting obscured IR AGN spectroscopic sample. We select the targets using an MIR colour criterion applied to the unWISE catalogue from the WISE ( Wide-field Infrared Survey Explorer ) all-sky survey, and then apply a r −W 2 ≥5 . 9 mag cut; we demonstrate that this selection will mostly identify sources obscured by N H > 10 22 cm −2 . The surv e y complements the 4MOST X-ray surv e y, which will follow up ∼1 M eROSITA (extended ROentgen Surv e y with an Imaging Telescope Array)- selected (typically unobscured) AGN. We perform simulations to predict the quality of the spectra that we will obtain and validate our MIR-optical colour-selection method using X-ray spectral constraints and UV-to-far-IR spectral energy distribution (SED) modelling in four well-observ ed deep-sk y fields. We find that: (1) ≈80 −87 per cent of the WISE -selected targets are AGN down to r AB = 22 . 1 −22 . 8 mag of which ≈70 per cent are obscured by N H > 10 22 cm −2 , and (2) ≈80 per cent of the 4MOST IR AGN sample will remain undetected by the deepest eROSITA observations due to extreme absorption. Our SED- fitting results show that the 4MOST IR AGN surv e y will primarily identify obscured AGN and quasars ( ≈55 per cent of the sample is expected to have L AGN , IR > 10 45 erg s −1 ) residing in massive galaxies ( M _ ≈10 10 −10 12 M _) at z ≈0 . 5 −3 . 5 with ≈33 per cent expected to be hosted by starburst galaxies.",

keywords = "infrared: galaxies, quasars: general, surveys",

author = "Carolina Andonie and Alexander, {David M.} and Claire Greenwell and Sotiria Fotopoulou and Ryan Hickox and Rosario, {David J.} and Carolin Villforth and Johannes Buchner and Krogager, {Jens Kristian} and Brivael Laloux and Andrea Merloni and Mara Salvato and Ole Streicher and Wei Yan",

year = "2025",

month = may,

day = "31",

doi = "10.1093/mnras/staf624",

language = "English",

volume = "539",

pages = "2202--2229",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "3",

}

TY - JOUR

T1 - An obscured quasar census with the 4MOST IR AGN survey

T2 - design, predicted properties, and scientific goals

AU - Andonie, Carolina

AU - Alexander, David M.

AU - Greenwell, Claire

AU - Fotopoulou, Sotiria

AU - Hickox, Ryan

AU - Rosario, David J.

AU - Villforth, Carolin

AU - Buchner, Johannes

AU - Krogager, Jens Kristian

AU - Laloux, Brivael

AU - Merloni, Andrea

AU - Salvato, Mara

AU - Streicher, Ole

AU - Yan, Wei

PY - 2025/5/31

Y1 - 2025/5/31

N2 - We present the 4MOST (4-metre Multi-Object Spectroscopic Telescope) infrared (IR) AGN surv e y, the first large-scale optical spectroscopic surv e y characterizing mid-infrared (MIR) selected obscured active galactic nuclei (AGNs). The surv e y targets ≈212 000 obscured IR AGN candidates o v er ≈10 000 de g 2 down to a magnitude limit of r AB = 22 . 8 mag and will be ≈100 ×larger than an y e xisting obscured IR AGN spectroscopic sample. We select the targets using an MIR colour criterion applied to the unWISE catalogue from the WISE ( Wide-field Infrared Survey Explorer ) all-sky survey, and then apply a r −W 2 ≥5 . 9 mag cut; we demonstrate that this selection will mostly identify sources obscured by N H > 10 22 cm −2 . The surv e y complements the 4MOST X-ray surv e y, which will follow up ∼1 M eROSITA (extended ROentgen Surv e y with an Imaging Telescope Array)- selected (typically unobscured) AGN. We perform simulations to predict the quality of the spectra that we will obtain and validate our MIR-optical colour-selection method using X-ray spectral constraints and UV-to-far-IR spectral energy distribution (SED) modelling in four well-observ ed deep-sk y fields. We find that: (1) ≈80 −87 per cent of the WISE -selected targets are AGN down to r AB = 22 . 1 −22 . 8 mag of which ≈70 per cent are obscured by N H > 10 22 cm −2 , and (2) ≈80 per cent of the 4MOST IR AGN sample will remain undetected by the deepest eROSITA observations due to extreme absorption. Our SED- fitting results show that the 4MOST IR AGN surv e y will primarily identify obscured AGN and quasars ( ≈55 per cent of the sample is expected to have L AGN , IR > 10 45 erg s −1 ) residing in massive galaxies ( M _ ≈10 10 −10 12 M _) at z ≈0 . 5 −3 . 5 with ≈33 per cent expected to be hosted by starburst galaxies.

AB - We present the 4MOST (4-metre Multi-Object Spectroscopic Telescope) infrared (IR) AGN surv e y, the first large-scale optical spectroscopic surv e y characterizing mid-infrared (MIR) selected obscured active galactic nuclei (AGNs). The surv e y targets ≈212 000 obscured IR AGN candidates o v er ≈10 000 de g 2 down to a magnitude limit of r AB = 22 . 8 mag and will be ≈100 ×larger than an y e xisting obscured IR AGN spectroscopic sample. We select the targets using an MIR colour criterion applied to the unWISE catalogue from the WISE ( Wide-field Infrared Survey Explorer ) all-sky survey, and then apply a r −W 2 ≥5 . 9 mag cut; we demonstrate that this selection will mostly identify sources obscured by N H > 10 22 cm −2 . The surv e y complements the 4MOST X-ray surv e y, which will follow up ∼1 M eROSITA (extended ROentgen Surv e y with an Imaging Telescope Array)- selected (typically unobscured) AGN. We perform simulations to predict the quality of the spectra that we will obtain and validate our MIR-optical colour-selection method using X-ray spectral constraints and UV-to-far-IR spectral energy distribution (SED) modelling in four well-observ ed deep-sk y fields. We find that: (1) ≈80 −87 per cent of the WISE -selected targets are AGN down to r AB = 22 . 1 −22 . 8 mag of which ≈70 per cent are obscured by N H > 10 22 cm −2 , and (2) ≈80 per cent of the 4MOST IR AGN sample will remain undetected by the deepest eROSITA observations due to extreme absorption. Our SED- fitting results show that the 4MOST IR AGN surv e y will primarily identify obscured AGN and quasars ( ≈55 per cent of the sample is expected to have L AGN , IR > 10 45 erg s −1 ) residing in massive galaxies ( M _ ≈10 10 −10 12 M _) at z ≈0 . 5 −3 . 5 with ≈33 per cent expected to be hosted by starburst galaxies.

KW - infrared: galaxies

KW - quasars: general

KW - surveys

UR - http://www.scopus.com/inward/record.url?scp=105004188969&partnerID=8YFLogxK

U2 - 10.1093/mnras/staf624

DO - 10.1093/mnras/staf624

M3 - Article

AN - SCOPUS:105004188969

SN - 0035-8711

VL - 539

SP - 2202

EP - 2229

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -

An obscured quasar census with the 4MOST IR AGN survey: design, predicted properties, and scientific goals

Abstract

Data Availability Statement

Acknowledgements

Funding

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this