@article{20294,
  abstract     = {Little Red Dots (LRDs) are compact, point-like sources characterized by their red color and broad Balmer lines; it is a matter of debate whether they are dominated by active galactic nuclei (AGNs) or dusty star-forming galaxies (DSFGs). Here we report two LRDs (ID9094 and ID2756) at zspec > 7 recently discovered in the JWST FRESCO GOODS-North field. Both satisfy the “v-shaped” color and compactness criteria for LRDs and are identified as Type-I AGN candidates based on their broad Hβ emission lines (full width at half maximum: 2280 ± 490 km s−1 for ID9094 and 1070 ± 240 km s−1 for ID2756) and narrow [O III] lines (≃300 − 400 km s−1). To investigate their nature, we conducted deep NOEMA follow-up observations targeting the [C II] 158 μm emission line and the 1.3 mm dust continuum. We do not detect [C II] or 1.3 mm continuum emission for either source. If the two LRDs were DSFGs, we would expect significant detections: > 16σ for [C II] and > 3σ for the 1.3 mm continuum of ID9094, and > 5σ for the [C II] of ID2756. Using the 3σ upper limits of [C II] and 1.3 mm, we performed two analyses: (1) UV-to-far-infrared spectral energy distribution fitting with and without AGN components, and (2) comparison of their properties with the L[C II]–SFRtot empirical relation. Both analyses are consistent with a scenario in which AGN activity contributes to the observed properties, though a dusty star-forming origin cannot be fully ruled out. Our results highlight the importance of far-infrared observations for studying LRDs, a regime that remains largely unexplored.},
  author       = {Xiao, Mengyuan and Oesch, Pascal A. and Bing, Longji and Elbaz, David and Matthee, Jorryt J and Fudamoto, Yoshinobu and Fujimoto, Seiji and Marques-Chaves, Rui and Williams, Christina C. and Dessauges-Zavadsky, Miroslava and Valentino, Francesco and Brammer, Gabriel and Covelo-Paz, Alba and Daddi, Emanuele and Fynbo, Johan P.U. and Gillman, Steven and Ginolfi, Michele and Giovinazzo, Emma and Greene, Jenny E. and Gu, Qiusheng and Illingworth, Garth and Inayoshi, Kohei and Kokorev, Vasily and Meyer, Romain A. and Naidu, Rohan P. and Reddy, Naveen A. and Schaerer, Daniel and Shapley, Alice and Stefanon, Mauro and Steinhardt, Charles L. and Setton, David J. and Vestergaard, Marianne and Wang, Tao},
  issn         = {1432-0746},
  journal      = {Astronomy & Astrophysics},
  publisher    = {EDP Sciences},
  title        = {{No [C II] or dust detection in two Little Red Dots at zspec > 7}},
  doi          = {10.1051/0004-6361/202554361},
  volume       = {700},
  year         = {2025},
}