重力拡大鏡の背後にある銀河(Galaxies behind a gravitational magnifier)

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ジェームス・ウェッブ望遠鏡が解明した超遠方天体 The James Webb Telescope reveals highly distant objects

2022-07-28 マックス・プランク研究所

Zoom into space: This JWST image shows the galaxy cluster SMACS J0723.3−7327 with a large number of lensed background galaxies. The white bar at the bottom corresponds to 50 arcsec, which is approximately the maximum size of Jupiter observed from Earth.
© NASA, ESA, CSA and STScI

国際研究チームは、今月公開されたジェームス・ウェッブ宇宙望遠鏡(JWST)の最初の科学画像を用いて、銀河団 SMACS J0723.3-7327 の質量分布の改良モデルを構築することに成功しました。研究チームは、JWSTの画像から明らかになった遠方の背景銀河を何十枚も撮影し、そのうちのいくつかは、これまで検出できなかったほど暗いものであることを突き止めました。
JWSTが開く道への第一歩として、この新しい望遠鏡の最近のデータを用いて、SMACS0723のレンズ効果を非常に正確にモデル化した。
この共同研究は、まずハッブル宇宙望遠鏡(HST)とマルチユニット分光器(MUSE)のデータを使って「JWST以前」のレンズモデルを作り、それを新たに入手したJWSTの近赤外線画像で改良したものです。

<関連情報>

JWSTによる重力レンズの初観測。SMACS~J0723.3-7327 の近赤外線観測による新しい多重像の質量モデル First JWST observations of a gravitational lens: Mass model of new multiple images with near-infrared observations of SMACS~J0723.3−7327

G. B. Caminha, S. H. Suyu, A. Mercurio, G. Brammer, P. Bergamini, E. Vanzella, A. Acebron

Submitted on 15 Jul 2022

Comments:
Submitted to A&A Letters, lens model and redshift catalogue available at:
https://wwwmpa.mpa-garching.mpg.de/~caminha/SMACS0723_Caminha/

Subjects:
Astrophysics of Galaxies (astro-ph.GA)

Cite as:
arXiv:2207.07567 [astro-ph.GA]

(or arXiv:2207.07567v1 [astro-ph.GA] for this version)

First JWST observations of a gravitational lens: Mass model of new multiple images with near-infrared observations of SMACS~J0723.3$-27
We present our lens mass model of SMACS J0723, the first strong gravitational lens observed by the James Webb Space Telescope (JWST). We use data from the Hubbl...

We present our lens mass model of SMACS J0723, the first strong gravitational lens observed by the James Webb Space Telescope (JWST). We use data from the Hubble Space Telescope and Multi Unit Spectroscopic Explorer (MUSE) to build our ‘pre-JWST’ lens model, and refine it with newly available JWST near-infrared imaging in our JWST model. To reproduce the positions of all multiple lensed images with good accuracy, the adopted mass parameterization consists of one cluster-scale component, accounting mainly for the dark matter distribution, the galaxy cluster members and an external shear component. The pre-JWST model has, as constraints, 19 multiple images from six background sources, of which four have secure spectroscopic redshift measurements from this work. The JWST model has more than twice the number of constraints, 27 additional multiple images from another ten lensed sources. Both models can reproduce very well the multiple image positions with a δrms of 0.39′′ and 0.51′′, for the pre-JWST and JWST models, respectively. The total mass estimates within a radius of 128~kpc (~ the Einstein radius) are 7.9+0.3−0.2×1013M⊙ and 8.6+0.2−0.2×1013M⊙, for the pre-JWST and JWST models, respectively. We predict with our mass models the redshifts of the newly detected JWST sources, which are crucial information for systems without spectroscopic measurements for further studies and follow-up observations. Interestingly, one family detected with JWST is found to be at a very high redshift, z>7.5 (68% confidence level) and with one image having lensing magnification of |μ|=9.8+0.9−1.1, making it an interesting case for future studies. The lens models, including magnification maps and redshifts estimated from the model are made publicly available, along with the full spectroscopic redshift catalogue from MUSE.

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