2025ApJ...992...71R


Query : 2025ApJ...992...71R

2025ApJ...992...71R - Astrophys. J., 992, 71 (2025/October-2)

Not Just a Dot: The Complex UV Morphology and Underlying Properties of Little Red Dots.

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., JOHNSON B.D., HAINLINE K., HELTON J.M., LIN X., LYU J., MA Z., MAIOLINO R., PEREZ-GONZALEZ P.G., RIEKE M., ROBERTSON B.E., SHIVAEI I., STONE M., SUN Y., TACCHELLA S., UBLER H., WILLIAMS C.C., WILLMER C.N.A., WILLOTT C., ZHANG J. and ZHU Y.

Abstract (from CDS):

We analyze 99 photometrically selected Little Red Dots (LRDs) at z ≈ 4-8 in the GOODS fields, leveraging ultradeep JADES NIRCam short-wavelength (SW) data. Among the 99 selected LRDs, we examine the morphology of 30. The remaining 69 appear predominantly compact, with sizes ≲400 pc and no extended components even in stacked SW images. However, their unresolved nature may partly reflect current depth limitations, which could prevent the detection of faint diffuse components. Among the 30 morphologically analyzed LRDs, 50% show multiple associated components, while the rest exhibit highly asymmetric structures, despite appearing as single sources. This diversity in rest-frame UV morphologies may point to interactions or strong internal feedback. We find median stellar masses of ${{\mathrm{log}}_{10}}\,({M}_{\star }/{M}_{\odot })=9.0{7}_{-0.08}^{+0.11}$ for pure stellar models with ${A}_{V}\approx 1.1{6}_{-0.21}^{+0.11}$ mag, and ${{\mathrm{log}}_{10}}\,({M}_{\star }/{M}_{\odot })=9.6{7}_{-0.27}^{+0.17}$ for models including active galactic nuclei (AGNs) with ${A}_{V}\approx 2.7{4}_{-0.71}^{+0.55}$ mag, in line with recent studies suggesting higher masses and dust content for AGN-fitted LRDs. NIRSpec spectra are available for 15 sources, six of which are also in the morphological sample. Broad Hα is detected in 40% (FWHM = 1200-2900 km s–1), and one source shows broad Hβ emission. Emission line ratios indicate a composite nature, consistent with both AGN and stellar processes. Altogether, these results suggest that LRDs are a mixed population, and their rest-frame UV morphology reflects this complexity. Morphological studies of larger samples could provide a new way to understand what drives their properties and evolution.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): James Webb Space Telescope - Active galactic nuclei - Near infrared astronomy - Galaxy evolution - Galaxy formation

Status at CDS : All or part of tables of objects will be ingested in SIMBAD with priority 1.

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026
#notes
1 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 2282 1
2 NAME GOODS Southern Field reg 03 32 28.0 -27 48 30           ~ 1623 1
3 JADES-GS+053.12654-27.81809 AGN 03 32 30.37 -27 49 05.1           ~ 24 0
4 JADES-GS+053.15803-27.78632 EmG 03 32 37.91 -27 47 10.4           ~ 8 0
5 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 3639 0
6 [OBV2016] GN-z11 EmG 12 36 25.46 +62 14 31.4           ~ 247 0
7 NAME GOODS-N Field reg 12 36 55.0 +62 14 15           ~ 1364 1
8 NAME EGSY8p7 EmG 14 20 08.50 +52 53 26.6           ~ 101 0

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