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Welcome to the web page of Mona Molham, Research assistant, at Research Institute of Astronomy and Geophysics -NRIAG.
This composite image shows the galaxy cluster 1E 0657-556, also known as the "bullet cluster." This cluster was formed after the collision of two large clusters of galaxies, the most energetic event known in the universe since the Big Bang. Hot gas detected by Chandra in X-rays is seen as two pink clumps in the image and contains most of the "normal," or baryonic, matter in the two clusters. The bullet-shaped clump on the right is the hot gas from one cluster, which passed through the hot gas from the other larger cluster during the collision. An optical image from Magellan and the Hubble Space Telescope shows the galaxies in orange and white. The blue areas in this image depict where astronomers find most of the mass in the clusters. The concentration of mass is determined by analyzing the effect of so-called gravitational lensing, where light from the distant objects is distorted by intervening matter. Most of the matter in the clusters (blue) is clearly separate from the normal matter (pink), giving direct evidence that nearly all of the matter in the clusters is dark. The hot gas in each cluster was slowed by a drag force, similar to air resistance, during the collision. In contrast, the dark matter was not slowed by the impact because it does not interact directly with itself or the gas except through gravity. Therefore, during the collision the dark matter clumps from the two clusters moved ahead of the hot gas, producing the separation of the dark and normal matter seen in the image. If hot gas was the most massive component in the clusters, as proposed by alternative theories of gravity, such an effect would not be seen. Instead, this result shows that dark matter is required. Comparing the optical image with the blue emission shows that the most of the galaxies in each cluster are located near the two dark matter clumps. This shows that the galaxies in each cluster did not slow down because of the collision, unlike the hot gas.
Full Name: Mona Elhalaby
Scientifics Name: Mona Molham
Address: National Research Institute of Astronomy and Geophysics – NRIAG
Astronomy Department – Stellar Astronomy Lab
11421 – Helwan – Cairo – Egypt
- X-ray properties of XCLASS-redMaPPer galaxy cluster sample: The luminosity-temperature relation. Molham et al .2020.
- The 3XMM/SDSS Stripe 82 Galaxy Cluster Survey. II. X-ray and optical properties of the cluster sample. Takey et al .2019.
- Multiwavelength classification of X-ray selected galaxy cluster candidates using convolutional neural networks. Kosiba et al .2020.
- The X-CLASS survey: A catalogue of 1646 X-ray-selected galaxy clusters up to z ∼1. Koulouridis et al .2021.
- (KFISP) Kottamia Faint Imaging Spectro-Polarimeter: Opto-mechanical design and performance analysis. 2020.
- X-CLASS Team
The First Advanced ArAS School for Astrophysics (ArAS SfA-Adv1) held in Egypt from 16 to 22 October 2021.
The 5th ArAS school of astrophysics held in Egypt from 16 to 23 October 2020.
The 4th ArAS school of astrophysics held in Egypt from 19 to 26 October 2019
Groups and clusters in the 3XMM-Stripe 82 zone, The X-ray Universe 2017 – Cosmos – ESA (Conference).
Comparative Study of Magnetar Intermediate Flares and Recurrent Short Bursts from SGR1900+ 14, IAU General Assembly 22-2015.
Global Spectral Properties of SGR1900+14 Bursts Observed by SWIFT, Frontiers Space Astrophysics: Neutron Stars & Gamma Ray Bursts-2009(Conference).
Modelling the Emission from SGR 1900+14, AUC Annual Research Conference (2008)
Spectral and temporal properties of SGR1900+14 burst emission observed by SWIFT, The 8th COSPAR Capacity Building Workshop-2008