2009A&A...507...35A


Query : 2009A&A...507...35A

2009A&A...507...35A - Astronomy and Astrophysics, volume 507, 35-46 (2009/11-3)

COSMOS 5921+0638: characterization and analysis of a new strong gravitationally lensed AGN.

ANGUITA T., FAURE C., KNEIB J.-P., WAMBSGANSS J., KNOBEL C., KOEKEMOER A.M. and LIMOUSIN M.

Abstract (from CDS):

Strong lens candidates have been newly identified within the COSMOS field. We present VLT/FORS1 spectroscopic follow-up observations and HST/WFPC2 imaging of the system COSMOS 5921+0638, which exhibits quadruply lensed images and a perfect Einstein ring. We investigate the nature of COSMOS 5921+0638 by studying its photometric, spectroscopic and physical properties. By analyzing our VLT/FORS1 spectroscopy and Subaru/CFHT/HST imaging of COSMOS 5921+0638, we completed both an environmental analysis and detailed analytical and grid-based mass modeling to determine it properties. We measured the redshifts of the lensing galaxy in COSMOS 5921+0638 (zl=0.551±0.001) and 9 additional galaxies in the field (5 of them at z∼0.35). The redshift of the lensed source was inferred by identifying a candidate Lyα line at zs=3.14±0.05. The mass modeling reveals the requirement of a small external shear (γ=0.038), which is slightly larger than the lensing contribution expected by galaxy groups along the line-of-sight obtained from the zCOSMOS optical group catalog (κgroups∼0.01 and γgroups∼0.005). The estimated time-delays between the different images are of the order of hours to half a week and the total magnification of the background source is µ≃150. The measured mass-to-light ratio of the lensing galaxy within the Einstein ring is M/LB≃8.5±1.6. Anomalies are observed between the measured and expected flux ratios of the images of the background AGN. Our analysis indicates that the ring and point-like structures in COSMOS 5921+0638 consist of a lensed high redshift galaxy hosting a low luminosity AGN (LLAGN). The observed flux ratio anomalies are probably due to microlensing by stars in the lensing galaxy and/or a combination of static phenomena. Multi-epoch, multi-band space-based observations would allow us to differentiate between the possible causes of these anomalies, since static and/or dynamic variations could be identified. Because of its short time-delays and the possibility of microlensing, COSMOS 5921+0638 is a promising laboratory for future studies of LLAGNs.

Abstract Copyright:

Journal keyword(s): galaxies: individual: COSMOS 5921+0638 - galaxies: quasars: individual: COSMOS 5921+0638 - gravitational lensing - cosmology: observations

Nomenclature: Fig. 1: [AFK2009b] A (Nos A-D). Table 2, Fig. 3: [AFK2009b] JHHMMSS.ss+DDMMSS.s N=10.

Simbad objects: 21

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Number of rows : 21
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 4C 05.19 QSO 04 14 37.7673624 +05 34 42.328449   24.100 23.800 21.270   ~ 347 2
2 COSMOS 1716841 G 09 59 09.261 +02 07 55.08 23.591 22.38 20.918 20.270 19.613 ~ 10 0
3 COSMOS2015 555150 G 09 59 12.166 +02 08 25.71 23.016 22.40 21.082 20.584 19.989 ~ 9 0
4 COSMOS 1316165 G 09 59 12.37 +02 06 56.0 23.058 22.78 21.765 21.460 21.152 ~ 6 0
5 COSMOS 1678884 G 09 59 12.389 +02 07 51.01 24.16 23.12 21.692 21.043 20.418 ~ 10 0
6 COSMOS 1718062 G 09 59 14.744 +02 07 41.00 24.69 24.18 23.02 22.66 22.31 ~ 9 0
7 UVISTADR1 J095915.58+020611.4 G 09 59 15.58 +02 06 11.5 23.628 23.31 22.68 22.06 21.466 ~ 2 0
8 [FKC2008] COSMOS 5921+0638 gLS 09 59 21.7 +02 06 38           ~ 7 0
9 COSMOS 1317280 gLe 09 59 21.771 +02 06 38.40 25.06 23.31 22.13 21.410 20.625 ~ 11 0
10 COSMOS 1327947 G 09 59 30.27 +02 04 21.8 23.006 22.62 21.89 21.377 20.665 ~ 6 0
11 [BMM2014] 819631 G 09 59 32.633 +02 06 08.42 24.67 23.56 22.11 21.250 20.377 ~ 7 0
12 [AFK2009b] J095933.24+020547.6 G 09 59 33.24 +02 05 47.6           ~ 1 0
13 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 2591 0
14 QSO B1115+080A QSO 11 18 16.951 +07 45 58.23   16.61 16.44     ~ 660 2
15 QSO J1131-1231 QSO 11 31 51.5387 -12 31 58.716           ~ 244 1
16 WG 22 WD* 12 38 49.7811220835 -49 48 00.219515411   14.14 13.96     DA4.2 216 0
17 [VV2006] J203342.1-472343 QSO 20 33 42.12 -47 23 43.9           ~ 110 1
18 [AFK2009b] C LeI ~ ~           ~ 1 0
19 [AFK2009b] D LeI ~ ~           ~ 1 0
20 [AFK2009b] B LeI ~ ~           ~ 1 0
21 [AFK2009b] A LeI ~ ~           ~ 1 0

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2022.10.02-02:33:01

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