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Proposal Number: 10900076

Title: Deep Follow-up of Intermediate Redshift Groups in the XBootes Survey

PI Name: Gordon Garmire

We propose to observe two intermediate-redshift galaxy groups with Chandra to determine their temperature and X-ray luminosity to r_500. These observations are part of a larger program to observe a flux-limited sample of groups detected in the XBootes survey. The primary science goals of this project are (1) to exploit the unique multi-wavelength coverage of the XBootes field to understand the evolving relationships between the X-ray and optical properties of groups (2) to probe the evolution of group X-ray emission and constrain the non-gravitational physics affecting the energetics of the intragroup medium.

Proposal Number: 10900088

Title: The Origin and Evolution of Fossil Groups

PI Name: Gordon Garmire

We propose snapshot observations of 12 fossil group candidates for further follow-up with XMM-Newton. These targets have been identified from the maxBCG optical cluster survey (Koester et al. 2007) by selecting groups with extremely luminous and dominant brightest cluster galaxies (BCGs). They will represent the first large X-ray sample of bona-fide fossil groups. These observations will provide estimates of the diffuse X-ray flux for much deeper follow-up, and for the brightest targets, they will provide an estimate of the plasma temperature. This snapshot project requires the spatial resolution of Chandra to separate diffuse emission from point source emission; when combined with the sensitivity of XMM-Newton follow-ups, it will optimize the usage of these observatories.

Proposal Number: 10900117

Title: Identifying the host galaxies for optically dark gamma-ray bursts

PI Name: Andrew Levan

We propose to use the high spatial resolution of Chandra to obtain precise positions for a sample of Gamma-Ray Bursts (GRBs) with no optical afterglows, where the optical light is suppressed relative to the X-ray flux. These bursts are likely to be highly obscured and may have different environments from the optically bright GRBs. Our Chandra observations will (unlike Swift XRT positions) allow for the unique identification of a host galaxy. To locate these host galaxies we will follow up our Chandra positions with deep optical and IR observations with HST. The ultimate aim is to understand any differences between the host galaxies of optically dark and bright GRBs, and how these affect the use of GRBs as tracers of starformation and galaxy evolution at high redshift.

Proposal Number: 10900388

Title: Feedback at high-z and the joint formation of AGN and massive galaxies

PI Name: Ian Smail

Theoretical galaxy formation models appear to require a feedback mechanism which quenches star formation in massive galaxies at high-z. Inverse Compton scattering of the CMB by relativistic electrons in radio jets is one potential mechanism which occurs in the most massive galaxies at high-z. There is strong evidence for IC scattering from deep Chandra imaging of 2 high-z radio galaxies and here we request time to double this sample with 100-ks observations of two further radio galaxies to confirm the ubiquity of IC halos around these massive galaxies. These deep X-ray images will also uncover overdensities of luminous AGN associated with far-IR-luminous companions, providing a census of black-hole growth and merging in high-density regions surrounding these radio galaxies.

Proposal Number: 10900553

Title: Understanding Group Evolution with Chandra

PI Name: Eric Miller

Galaxy groups are vital to our understanding of structure formation, cluster evolution, and galaxy evolution, yet they are difficult to study at even moderate redshift. We propose Chandra/ACIS observations of two groups as part of an ongoing project to observe a flux-limited sample of intermediate-redshift (z > 0.1) groups identified by the XBootes Chandra survey. This will complete a flux-limited subset of the sample for which we have confirmed group redshifts. With the unique multiwavelength coverage of the XBootes field, we aim to understand the physical connection between the X-ray and optical properties of groups, and to probe the evolution of group X-ray emission in order to constrain the non-gravitational physics affecting the energetics of the intragroup medium.

Proposal Number: 10900836

Title: A Benchmark Observation of the Warm-Hot Intergalactic Medium

PI Name: Taotao Fang

Searching for the ``Missing baryons'', in the form of the warm-hot intergalactic medium (WHIM), is a fundamental challenge faced by the current theory of structure formation. Cosmological simulations predict that majority of the WHIM can be probed in X-ray only, yet the reported detections are often in question due to statistical and systematical issues. Based on the tentative evidence in our joint XMM-Chandra ToO observations of H 2356-309, we propose a deep, non-ToO Chandra observation to definitively detect the WHIM absorption line with a measured column density expected from theory. A null detection would place an upper limit which cannot be explained by current cosmological simulations, and put future pursuit of the WHIM with current generation of X-ray telescopes in question.

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The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2025. All rights reserved.