The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000
The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000
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DOI：
10.1051/0004-6361/202040108
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发表时间：
2021-06-22
影响因子：
6.5
通讯作者：
Visser, Manus
中科院分区：
文献类型：
--
作者：
Brouwer, Margot M.;Oman, Kyle A.;Visser, Manus
我们提出了孤立星系周围的径向引力加速度的测量，比较重子物质（g（bar））与观测到的引力加速度（g（obs））的预期引力加速度，使用弱透镜测量从第四次数据发布的千度巡天（KiDS-1000）。这些测量扩展了传统上使用星系旋转曲线测量的径向加速度关系（RAR），以g（obs）为单位的20年进入可观测星系外围以外的低加速度区域。我们将我们的RAR测量结果与两个修正的引力（MG）理论的预测进行比较：修正的牛顿动力学和Verlinde的紧急引力（EG）。我们发现g（obs）和g（bar）之间的测量关系与MG预测一致。此外，我们发现，早期和晚期型星系（分裂的Sersic指数和u-r颜色）具有相同的恒星质量的RAR之间的差异至少为6西格玛。目前的MG理论涉及的重力修正是独立于其他星系的属性，这将无法解释这种行为，虽然EG理论仍然局限于球对称静态质量模型。如果只有早型星系具有显著的（M-气体近似于M-恒星）环星系气体晕，则可以解释这种差异。在Lambda冷暗物质（Lambda CDM）模型中，星系与晕的质量关系取决于星系的形成历史，这也是我们所预期的。我们发现，MICE，一个Lambda CDM模拟与混合晕占据分布建模和丰度匹配，再现所观察到的RAR，但显着不同的BAHAMAS，流体动力学宇宙学星系形成模拟。我们的研究结果对环星系气体的数量很敏感;目前的观测限制表明，由此产生的修正可能是温和的。如果星系周围重子质量分布的系统不确定性减少，那么未来宇宙学调查（如欧几里得）对透镜RAR的测量将能够进一步区分MG和Lambda CDM模型。
We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (g(bar)) with the observed gravitational acceleration (g(obs)), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in g(obs) into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde's emergent gravity (EG). We find that the measured relation between g(obs) and g(bar) agrees well with the MG predictions. In addition, we find a difference of at least 6 sigma between the RARs of early- and late-type galaxies (split by Sersic index and u-r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (M-gas approximate to M-star) circumgalactic gaseous haloes. The observed behaviour is also expected in Lambda -cold dark matter (Lambda CDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a Lambda CDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and Lambda CDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.