Limits on Cosmological Models from Radio-selected Gravitational Lenses
Limits on Cosmological Models from Radio-selected Gravitational Lenses
复制标题
射电选择引力透镜宇宙学模型的限制
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
J. Munoz
中科院分区：
文献类型：
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作者：
E. Falco;C. Kochanek;J. Munoz
我们正在对177个平谱射电源进行红移测量，包括5 GHz流量范围50-100、100-200和200-250 mJy的三个样本。到目前为止，我们已经测量了124个红移，完备度分别为80%、68%和58%，适用于亮、中、暗通量范围。利用新确定的红移分布，我们可以从Jodrell Bank-VLA天体测量调查样本中的六个引力透镜的统计中得出宇宙学极限，该样本包括2500个5千兆赫亮度大于200mJy的平谱射电源。对于具有宇宙学常数的扁平宇宙模型，仅使用射电数据的极限为2σ时的Ω0>；0.27(1σ时为0.47<；Ω0<；1.38)。这些极限与透镜类星体的极限在统计上是一致的，并且假设没有旋涡星系产生的类星体透镜，对于我们最保守的红移完整性模型，射电+光学样本在2σ时需要0.38时的Ω0>；(0.64lt；Ω0<；1.66时为1σ)。我们的最佳拟合模型改进了大约1σ，如果早期类型星系的消亡使透镜类星体变弱Δm=0.58±0.45mag，但我们仍然发现在平坦宇宙学中Ω0>；0.26时的极限为2σ。在较弱的射电流量下，射电星系相对于类星体的比例增加(从1Jy时的~10%上升到0.1Jy时的~50%)，这解释了为什么透镜光学发射在射电透镜中很常见，也部分解释了射电选择透镜的红色。
We are conducting a redshift survey of 177 flat-spectrum radio sources in three samples covering the 5 GHz flux ranges 50-100, 100-200, and 200-250 mJy. So far, we have measured 124 redshifts with completenesses of 80%, 68%, and 58% for the bright, intermediate, and faint flux ranges. Using the newly determined redshift distribution, we can derive cosmological limits from the statistics of the six gravitational lenses in the Jodrell Bank-VLA Astrometric Survey sample of 2500 flat-spectrum radio sources brighter than 200 mJy at 5 GHz. For flat cosmological models with a cosmological constant, the limit using only radio data is Ω0 > 0.27 at 2 σ (0.47 < Ω0 < 1.38 at 1 σ). The limits are statistically consistent with those for lensed quasars, and the combined radio + optical sample requires Ω0 > 0.38 at 2 σ (0.64 < Ω0 < 1.66 at 1 σ) for our most conservative redshift completeness model, assuming that there are no quasar lenses produced by spiral galaxies. Our best-fit model improves by approximately 1 σ if extinction in the early-type galaxies makes the lensed quasars fainter by Δm = 0.58 ± 0.45 mag, but we still find a limit of Ω0 > 0.26 at 2 σ in flat cosmologies. The increasing fraction of radio galaxies as compared to quasars at fainter radio fluxes (rising from ~10% at 1 Jy to ~50% at 0.1 Jy) explains why lensed optical emission is common for radio lenses and partly explains the red color of radio-selected lenses.