_version_ 1866912992105332736
author Mazzolari, Giovanni
Übler, Hannah
Camus, Rodrigo Herrera
Davies, Ric
Tacconi, Linda
Lutz, Dieter
Schreiber, Natascha Förster
D'Eugenio, Francesco
Lee, Minju
Barfety, Capucine
Bertola, Elena
Bunker, Andrew
Burkert, Andreas
Chen, Jianhang
Cresci, Giovanni
Eisenhauer, Frank
Salcedo, Juan Manuel Espejo
Flesch, Simon
Genzel, Reinhard
Ji, Xihan
Lee, Lilian
Liu, Daizhong
Marconcini, Cosimo
Maiolino, Roberto
Naab, Thorsten
Shachar, Amit Nestor
Pannikkote, Meghana
Parlanti, Eleonora
Pastras, Stavros
Perna, Michele
Pulsoni, Claudia
del Pino, Bruno Rodriguez
Sturm, Eckhard
Shimizu, Taro
Tozzi, Giulia
author_facet Mazzolari, Giovanni
Übler, Hannah
Camus, Rodrigo Herrera
Davies, Ric
Tacconi, Linda
Lutz, Dieter
Schreiber, Natascha Förster
D'Eugenio, Francesco
Lee, Minju
Barfety, Capucine
Bertola, Elena
Bunker, Andrew
Burkert, Andreas
Chen, Jianhang
Cresci, Giovanni
Eisenhauer, Frank
Salcedo, Juan Manuel Espejo
Flesch, Simon
Genzel, Reinhard
Ji, Xihan
Lee, Lilian
Liu, Daizhong
Marconcini, Cosimo
Maiolino, Roberto
Naab, Thorsten
Shachar, Amit Nestor
Pannikkote, Meghana
Parlanti, Eleonora
Pastras, Stavros
Perna, Michele
Pulsoni, Claudia
del Pino, Bruno Rodriguez
Sturm, Eckhard
Shimizu, Taro
Tozzi, Giulia
contents We targeted with deep NOEMA observations the [CII]158$μ$m emission of three JWST-discovered AGN at z>6. Two of them have the typical features of Little Red Dots (LRDs), while the third one is a blue, extended, Type I AGN. We do not significantly detect [CII] emission or dust continuum in any of the targets, even after stacking. The resulting [CII] luminosity upper limits, $\log (L_{[CII]}/L_{\odot})<7.77-8.1$, lie $\sim2σ$ below the values expected from the [CII]-SFR relation, and we explore different scenarios to explain the lack of [CII]. We obtained upper limits on the gas masses of $\log (M_{gas}/M_{\odot})<9.26-9.59$ corresponding to $\log( M_{dust}/M_{\odot})<5.68-6.55$ assuming a metallicity dependent dust to gas ratio. Using the continuum non-detections (rms $\sim 16-25 ~μJy$) together with JWST/MIRI constraints, we performed a revised SED-fitting decomposition, resulting in stellar masses up to $\sim 2$ dex lower than previously reported, and implying $0.03\lesssim M_{BH}/M_{*}\lesssim0.7$. For the two LRDs, the SED is well reproduced by stellar emission in the rest-frame UV, while the rising rest-frame optical slope, flattening toward the near-infrared, is consistent with emission from a Type I AGN partially obscured along the polar direction with $E(B-V)_{\rm polar}\simeq 1$, in agreement with attenuation derived from the broad lines Balmer decrement. This decomposition demonstrates that a relatively standard AGN configuration can reproduce the SEDs of the two LRDs, without invoking more exotic scenarios. Finally, we investigate the positions of the three sources in the $IRX-β_{UV}$ plane, finding that they lie in a parameter space where galaxies are typically characterized by patchy dust distributions. Our analysis highlights the importance of millimeter constraints to characterize the different physical properties of high-z AGN.
format Preprint
id arxiv_https___arxiv_org_abs_2603_29652
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Constraints on the host galaxy and AGN properties of three z > 6 JWST AGN from NOEMA observations
Mazzolari, Giovanni
Übler, Hannah
Camus, Rodrigo Herrera
Davies, Ric
Tacconi, Linda
Lutz, Dieter
Schreiber, Natascha Förster
D'Eugenio, Francesco
Lee, Minju
Barfety, Capucine
Bertola, Elena
Bunker, Andrew
Burkert, Andreas
Chen, Jianhang
Cresci, Giovanni
Eisenhauer, Frank
Salcedo, Juan Manuel Espejo
Flesch, Simon
Genzel, Reinhard
Ji, Xihan
Lee, Lilian
Liu, Daizhong
Marconcini, Cosimo
Maiolino, Roberto
Naab, Thorsten
Shachar, Amit Nestor
Pannikkote, Meghana
Parlanti, Eleonora
Pastras, Stavros
Perna, Michele
Pulsoni, Claudia
del Pino, Bruno Rodriguez
Sturm, Eckhard
Shimizu, Taro
Tozzi, Giulia
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
We targeted with deep NOEMA observations the [CII]158$μ$m emission of three JWST-discovered AGN at z>6. Two of them have the typical features of Little Red Dots (LRDs), while the third one is a blue, extended, Type I AGN. We do not significantly detect [CII] emission or dust continuum in any of the targets, even after stacking. The resulting [CII] luminosity upper limits, $\log (L_{[CII]}/L_{\odot})<7.77-8.1$, lie $\sim2σ$ below the values expected from the [CII]-SFR relation, and we explore different scenarios to explain the lack of [CII]. We obtained upper limits on the gas masses of $\log (M_{gas}/M_{\odot})<9.26-9.59$ corresponding to $\log( M_{dust}/M_{\odot})<5.68-6.55$ assuming a metallicity dependent dust to gas ratio. Using the continuum non-detections (rms $\sim 16-25 ~μJy$) together with JWST/MIRI constraints, we performed a revised SED-fitting decomposition, resulting in stellar masses up to $\sim 2$ dex lower than previously reported, and implying $0.03\lesssim M_{BH}/M_{*}\lesssim0.7$. For the two LRDs, the SED is well reproduced by stellar emission in the rest-frame UV, while the rising rest-frame optical slope, flattening toward the near-infrared, is consistent with emission from a Type I AGN partially obscured along the polar direction with $E(B-V)_{\rm polar}\simeq 1$, in agreement with attenuation derived from the broad lines Balmer decrement. This decomposition demonstrates that a relatively standard AGN configuration can reproduce the SEDs of the two LRDs, without invoking more exotic scenarios. Finally, we investigate the positions of the three sources in the $IRX-β_{UV}$ plane, finding that they lie in a parameter space where galaxies are typically characterized by patchy dust distributions. Our analysis highlights the importance of millimeter constraints to characterize the different physical properties of high-z AGN.
title Constraints on the host galaxy and AGN properties of three z > 6 JWST AGN from NOEMA observations
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2603.29652