Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2503.01945 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866909753139003392 |
|---|---|
| author | Xiao, Mengyuan Oesch, Pascal A. Bing, Longji Elbaz, David Matthee, Jorryt Fudamoto, Yoshinobu Fujimoto, Seiji Marques-Chaves, Rui Williams, Christina C. Dessauges-Zavadsky, Miroslava Valentino, Francesco Brammer, Gabriel Covelo-Paz, Alba Daddi, Emanuele Fynbo, Johan P. U. Gillman, Steven Ginolfi, Michele Giovinazzo, Emma Greene, Jenny E. Gu, Qiusheng Illingworth, Garth Inayoshi, Kohei Kokorev, Vasily Meyer, Romain A. Naidu, Rohan P. Reddy, Naveen A. Schaerer, Daniel Shapley, Alice Stefanon, Mauro Steinhardt, Charles L. Setton, David J. Vestergaard, Marianne Wang, Tao |
| author_facet | Xiao, Mengyuan Oesch, Pascal A. Bing, Longji Elbaz, David Matthee, Jorryt Fudamoto, Yoshinobu Fujimoto, Seiji Marques-Chaves, Rui Williams, Christina C. Dessauges-Zavadsky, Miroslava Valentino, Francesco Brammer, Gabriel Covelo-Paz, Alba Daddi, Emanuele Fynbo, Johan P. U. Gillman, Steven Ginolfi, Michele Giovinazzo, Emma Greene, Jenny E. Gu, Qiusheng Illingworth, Garth Inayoshi, Kohei Kokorev, Vasily Meyer, Romain A. Naidu, Rohan P. Reddy, Naveen A. Schaerer, Daniel Shapley, Alice Stefanon, Mauro Steinhardt, Charles L. Setton, David J. Vestergaard, Marianne Wang, Tao |
| contents | Little Red Dots (LRDs) are compact, point-like sources characterized by their red color and broad Balmer lines, which have been debated to be either dominated by active galactic nuclei (AGN) or dusty star-forming galaxies (DSFGs). Here we report two LRDs (ID9094 and ID2756) at z$_{\rm spec}$>7, recently discovered in the JWST FRESCO GOODS-North field. Both satisfy the "v-shape" colors and compactness criteria for LRDs and are identified as Type-I AGN candidates based on their broad H$β$ emission lines (full width at half maximum: 2280$\pm$490 km/s for ID9094 and 1070$\pm$240 km/s for ID2756) and narrow [OI] lines ($\sim$ 300-400 km/s). To investigate their nature, we conduct deep NOEMA follow-up observations targeting the [CII] 158${\rm μm}$ emission line and the 1.3 mm dust continuum. We do not detect [CII] or 1.3 mm continuum emission for either source. Notably, in the scenario that the two LRDs were DSFGs, we would expect significant detections: $>16σ$ for [CII] and $>3σ$ for the 1.3 mm continuum of ID9094, and $>5σ$ for [CII] of ID2756. Using the 3$σ$ upper limits of [CII] and 1.3 mm, we perform two analyses: (1) UV-to-FIR spectral energy distribution (SED) fitting with and without AGN components, and (2) comparison of their properties with the L$_{[CII]}$-SFR$_{tot}$ empirical relation. Both analyses are consistent with a scenario where AGN activity may contribute 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_01945 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | No [CII] or dust detection in two Little Red Dots at z$_{\rm spec}$ > 7 Xiao, Mengyuan Oesch, Pascal A. Bing, Longji Elbaz, David Matthee, Jorryt Fudamoto, Yoshinobu Fujimoto, Seiji Marques-Chaves, Rui Williams, Christina C. Dessauges-Zavadsky, Miroslava Valentino, Francesco Brammer, Gabriel Covelo-Paz, Alba Daddi, Emanuele Fynbo, Johan P. U. Gillman, Steven Ginolfi, Michele Giovinazzo, Emma Greene, Jenny E. Gu, Qiusheng Illingworth, Garth Inayoshi, Kohei Kokorev, Vasily Meyer, Romain A. Naidu, Rohan P. Reddy, Naveen A. Schaerer, Daniel Shapley, Alice Stefanon, Mauro Steinhardt, Charles L. Setton, David J. Vestergaard, Marianne Wang, Tao Astrophysics of Galaxies Little Red Dots (LRDs) are compact, point-like sources characterized by their red color and broad Balmer lines, which have been debated to be either dominated by active galactic nuclei (AGN) or dusty star-forming galaxies (DSFGs). Here we report two LRDs (ID9094 and ID2756) at z$_{\rm spec}$>7, recently discovered in the JWST FRESCO GOODS-North field. Both satisfy the "v-shape" colors and compactness criteria for LRDs and are identified as Type-I AGN candidates based on their broad H$β$ emission lines (full width at half maximum: 2280$\pm$490 km/s for ID9094 and 1070$\pm$240 km/s for ID2756) and narrow [OI] lines ($\sim$ 300-400 km/s). To investigate their nature, we conduct deep NOEMA follow-up observations targeting the [CII] 158${\rm μm}$ emission line and the 1.3 mm dust continuum. We do not detect [CII] or 1.3 mm continuum emission for either source. Notably, in the scenario that the two LRDs were DSFGs, we would expect significant detections: $>16σ$ for [CII] and $>3σ$ for the 1.3 mm continuum of ID9094, and $>5σ$ for [CII] of ID2756. Using the 3$σ$ upper limits of [CII] and 1.3 mm, we perform two analyses: (1) UV-to-FIR spectral energy distribution (SED) fitting with and without AGN components, and (2) comparison of their properties with the L$_{[CII]}$-SFR$_{tot}$ empirical relation. Both analyses are consistent with a scenario where AGN activity may contribute 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. |
| title | No [CII] or dust detection in two Little Red Dots at z$_{\rm spec}$ > 7 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2503.01945 |