Not Just a Dot: the complex UV morphology and underlying properties of Little Red Dots
| Autor: | Rinaldi, P., Bonaventura, N., Rieke, G. H., Alberts, S., Caputi, K. I., Baker, W. M., Baum, S., Bhatawdekar, R., Bunker, A. J., Carniani, S., Curtis-Lake, E., D'Eugenio, F., Egami, E., Ji, Z., Hainline, K., Helton, J. M., Lin, X., Lyu, J., Johnson, B. D., Ma, Z., Maiolino, R., Pérez-González, P. G., Rieke, M., Robertson, B. E., Shivaei, I., Stone, M., Sun, Y., Tacchella, S., Übler, H., Williams, C. C., Willmer, C. N. A., Willott, C., Zhang, J., Zhu, Y. |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | We analyze 99 photometrically selected Little Red Dots (LRDs) at z ~ 4-8 in the GOODS fields, leveraging ultra-deep JADES NIRCam short-wavelength (SW) data. We examine the morphology of 30 LRDs; the remaining 69 are predominantly compact, i.e. are strongly dominated by sources < 400 pc in diameter and lack extended components even in stacked SW band images. Among the LRDs selected for morphological analysis, 50% show at least two distinct, associated sources or galaxy components, while the others appear as single sources with highly asymmetric structures. We find median stellar masses of log10(M*/Msun) = 9.07(-0.08)(+0.11) for pure stellar models with Av ~ 1.16(+0.11)(-0.21) mag, and log10(M*/Msun) = 9.67(+0.17)(-0.27) for models including AGNs, where Av ~ 2.74(+0.55)(-0.71) mag, consistent with recent results showing LRDs tend to have high stellar masses and dust content when fitted with AGN models. NIRSpec spectra are available for 15 sources, 6 of which fall within the morphological analysis sample and show multiple components. Among these 15, broad H-alpha emission is detected in 40%, with full-width half-maximum (FWHM) ranging from 1200 to 2900 km/s. One source exhibits broad H-beta emission with FWHM = 2000 +/- 500 km/s. Analysis of line ratios probing the interstellar medium (ISM) reveals a composite nature, indicating AGN activity combined with stellar processes. These findings suggest LRDs have a mixed nature, with AGN signatures in some cases linked to disturbed morphologies observed at rest-frame UV wavelengths. Comment: 28 pages, 9 figures, 3 tables. Submitted to ApJ. Comments are welcome! |
| Databáze: | arXiv |
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