2025A&A...696L..14S

Query : 2025A&A...696L..14S

2025A&A...696L..14S - Astronomy and Astrophysics, volume 696L14 (2025/4-1)

The COSMOS-Web ring: Spectroscopic confirmation of the background source at z = 5.1.

SHUNTOV M., JIN S., MERCIER W., KARTALTEPE J.S., LARSON R., KHOSTOVAN A.A., GAVAZZI R., NIGHTINGALE J.W., ILBERT O., ARANGO-TORO R., FRANCO M., AKINS H.B., CASEY C.M., McCRACKEN H.J., CIESLA L., MAGDIS G.E., AMVROSIADIS A., ENIA A., FAISST A.L., KOEKEMOER A.M., LAIGLE C., LE BORGNE D., MASSEY R., MOUTARD T. and VACCARI M.

Abstract (from CDS):

We report the spectroscopic confirmation of the background source of the most distant Einstein ring known to date, the COSMOS-Web ring. This system consists of a complete Einstein ring at z = 5.1, which is lensed by a massive early-type galaxy at z ∼ 2. The redshift z = 5.1043 ± 0.0004 is unambiguously identified with our NOEMA and Keck/MOSFIRE spectroscopy; the NOEMA observations reveal the CO(4-3) and CO(5-4) lines at > 8σ, and the MOSFIRE data detect [O II] at ∼6σ. Using multiwavelength photometry spanning near-infrared to radio bands, we find that the lensed galaxy is a dust-obscured starburst (M_⋆ ∼ 1.8 × 10¹⁰ M_⊙, SFR_IR ∼ 60 M_⊙ yr^–1) with a high star formation efficiency (gas depletion time τ_dep < 100 Myr), as indicated by the [C I](1-0) non-detection. The redshift confirmation re-validates that the total lens mass budget within the Einstein radius is fully accounted for by the stellar and dark matter components, without the need of modifying the initial mass function or dark matter distribution profile. This work paves the way for detailed studies and future follow-ups of this unique lensing system, which is an ideal laboratory for studying mass distribution at z ∼ 2 and physical conditions of star formation at z ∼ 5.

Abstract Copyright: © The Authors 2025

Journal keyword(s): galaxies: distances and redshifts - galaxies: high-redshift

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

Simbad objects: 1

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Number of rows : 1

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	COSMOS 896863	gLe	10 00 24.11	+01 53 35.7			28.022			~	5	0

Query : 2025A&A...696L..14S

Basic data :

COSMOS 896863 -- Gravitational Lens

gLe (2024NatAs), G (COSMOS)

10 00 24.11 +01 53 35.7 (Optical) [ ] C 2007ApJS..172...99C

09 57 49.18 +02 08 01.7 [ ]

237.14978 +41.92452 [ ]

V(km/s) 223552 [~] / z(photometric) 1.62 [~] / cz 485664 [~] E 2007ApJS..172...99C

V (AB) 28.022 [0.763] C 2007ApJS..172...99C

K (AB) 21.746 [0.449] C 2007ApJS..172...99C

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COSMOS 896863 COSMOS J100024.11+015335.7

References (5 between 1850 and 2026) (Total 5)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).

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Data at NED - NASA/IPAC Extragalactic Database : COSMOS 896863

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COSMOS 896863

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