Chandra Large and Very Large Projects

Proposal Number: 02800845

Title: A COMPLETE X-RAY CLUSTER SAMPLE AT Z > 0.8

PI Name: Spencer Stanford

We propose to observe three X-ray selected clusters of galaxies from the RDCS, one at z = 1.1 and two at z ~ 0.8. In conjunction with other data already being obtained by Chandra and XMM, we would then have luminosity and temperature measurements for a complete sample of 8 clusters at z > 0.8. We will produce the first temperature function at these high redshifts. Using Chandra's high angular resolution, we can minimize the contamination from point sources, a serious problem at faint flux limits, as well as study the spatial properties of the intra-cluster medium. With this combination of temperatures, luminosities, and spatial profiles, we will both probe the cluster mass function of the universe at high redshift and study the thermal history of the intra-cluster medium.

Proposal Number: 03800272

Title: MACS: THE X-RAY PROPERTIES OF THE MOST MASSIVE GALAXY CLUSTERS AT Z>0.3

PI Name: Harald Ebeling

We propose ACIS-I and HST observations of 30 distant and very X-ray luminous clusters (z>0.3, Lx>1e45) detected in the MAssive Cluster Survey (MACS). 22 of these 30 are new discoveries. Our targets are the high-z counterparts of the best-studied local systems and, combined with 4 others scheduled for observation, form a statistical sample >10 times larger than any previous one in this redshift and luminosity range. Chandra's unique capabilities will allow us to obtain spatially resolved gas temperature and density maps to constrain both the cosmological and physical parameters governing the evolution of the most massive clusters at z<0.5. The proposed observations are complemented by extensive groundbased follow-up studies of weak gravitational lensing, galaxy dynamics and the SZ effect.

Proposal Number: 04800280

Title: SURVEYING THE FORNAX CLUSTER OF GALAXIES

PI Name: Caleb Scharf

Low luminosity X-ray clusters of galaxies are the dominant reservoirs of bound matter in the Universe. At a distance of 20 Mpc, the Fornax cluster has an immense collection of the highest quality multi-wavelength data, making it an exceptional laboratory for studying the astrophysics of these systems. We propose surveying an inner region of Fornax with Chandra's unprecedented combination of spatial and spectral resolution to produce a keystone dataset with a long-term legacy. We will investigate the interactions of cluster galaxies with the ICM, their populations of globular clusters, search for emission from dwarf galaxies, ultra-compact systems, and intra-cluster planetary nebulae, and compare the ICM metal contents with the detailed history of stellar populations in Fornax.

Proposal Number: 04800927

Title: CHANDRA OBSERVATIONS OF DLS SHEAR-SELECTED CLUSTERS

PI Name: John Hughes

We propose Chandra observations of the most massive clusters currently identified from the Deep Lens Survey (DLS). The DLS is a deep multicolor (BVRz') imaging survey of 28 square degree being carried out at the 4-m telescopes of the US National Observatories (KPNO and CTIO). The DLS shear-selected cluster sample makes it possible for the first time to study clusters in a baryon-independent way. We are pursuing detailed investigations of this sample with HST and ground-based Keck spectroscopy. Chandra observations will meet multiple high-impact scientific goals, specifically, testing the ``fair sample'' hypothesis, calibrating the relationships between cluster mass, size, X-ray luminosity and temperature, and studying the evolution of these relationships with look-back time.

Proposal Number: 05800170

Title: A Megasecond Image of the Core of the Perseus Cluster

PI Name: Andrew Fabian

We propose a further 800 ks observation of the Perseus cluster, A426, the X-ray brightest cluster of galaxies in the sky. By combining this observation with our current data we will obtain a 1 Ms "ultimate image" of the cluster. Our main goal is to quantify the ripples due to the propagating sound waves seen in our 200 ks image. A detailed understanding of the mechanisms in the nearby Perseus cluster will unable us to fully understand the solution to the "cooling flow problem". The Perseus cluster is the only extragalactic source with such a high ACIS-S surface brightness over many sq arcmin. We propose that it should be observed as deeply as possible with Chandra and before any further degradation takes place in the performance of the detectors or spacecraft.

Proposal Number: 05800890

Title: THE MOST INTERESTING CLUSTER IN THE UNIVERSE

PI Name: Maxim Markevitch

The galaxy cluster 1E0657-56 is a treasure trove of information on just about every problem in cluster physics. It is the only cluster known to have a shock front with M substantially greater than 1. The proposed 500 ks observation, combined with the existing 90 ks, will allow us to determine whether electrons are heated adiabatically or dissipatively in a shock and whether the electron-ion equilibration is efficient. We will search for an electron temperature precursor to the shock to estimate thermal conductivity. We also will determine the importance of gas turbulence and study the destruction of a cooling flow remnant by ram pressure. Combined with data from other wavelengths, this observation can also shed light on the nature of dark matter and the origin of cluster radio halos.

Proposal Number: 06800101

Title: DARK ENERGY WITH X-RAY CLUSTERS: CHANDRA OBSERVATIONS OF 41 HIGH-REDSHIFT CLUSTERS FROM THE 400 deg^2 ROSAT PSPC SURVEY

PI Name: Alexey Vikhlinin

We propose Chandra observations to measure temperature and gas mass in a sample of 41 high-z galaxy clusters from our 400 deg^2 ROSAT survey. This sample is comparable in number to all clusters in the local Universe (z<0.1) above a similar limiting mass, and covers a factor of 3 larger volume at z=0.4-1. Chandra observations will provide the total mass function estimates at =0.4, 0.5, and 0.65, which can be directly compared with the local measurements at =0.05. These data will provide a measurement of the dark energy equation of state via the cluster evolution test which is completely independent from SN Ia and CMB and has different degeneracies. Some targets in this proposal are in common with the HRC GTO proposal 06900018. These programs are not in conflict.

Proposal Number: 06800102

Title: A CHANDRA TREASURY OBSERVATION OF THE BEST EXAMPLE OF A CLUSTER COLD FRONT

PI Name: Alexey Vikhlinin

We propose a 450 ksec observation of A3667, the best example of a cluster cold front. A deep image of the best cold front by the highest angular resolution X-ray telescope will push the study of the physics of the intracluster medium to the limit. Our main goals are 1) to observe the turbulence in the intracluster medium by direct imaging of any perturbations of the front surface; 2) to study transport processes in the ICM using the gas density and temperature profiles across the front with a spatial resolution of 1/5 of the Coulomb mean free path; 3) to characterize the magnetic field structure by mapping the onset of the Kelvin-Helmholtz instability. The proposed deep Chandra image of A3667 will be one of the treasury images of the X-ray astronomy.

Proposal Number: 06800613

Title: The History of AGN Activity in M87 and the Interaction of Nuclear Outbursts with the Surrounding Atmosphere

PI Name: William Forman

We propose a 500 ksec ACIS-I observation to study the interaction between energy outbursts from the supermassive black hole (SMBH) in M87 and its surrounding gaseous atmosphere. We will inventory the plasma bubbles inflated by the SMBH, search for weak shocks, study the interaction of relativistic plasma in bubbles with the surrounding hot gas, measure turbulence in the cluster gas, study the microphysics of the interaction between the plasma in the bubbles and the surrounding gas, and estimate the gas viscosity by measuring the width of shock fronts. By determining the energy associated with bubbles and shocks, we can chronicle the mechanical power output of the SMBH. Finally we will study particle acceleration and cooling models by measuring inter-knot spectra along the jet.

Proposal Number: 07800432

Title: The Cosmological Formation of Galaxy Groups

PI Name: DAVID BUOTE

One of the strongest, untested cosmological predictions is the scatter of the concentrations of dark matter halos on the group scale. To quantify this scatter of concentrations requires well-defined samples. We propose a novel systematic study of the core properties of 15 groups representing a complete, X-ray flux-limited sample. In addition to dark matter properties, we will address: (1) entropy and non-gravitational heating, (2) central iron abundances and stellar enrichment, (3) AGN heating and the cooling flow paradox, and (4) the formation of central galaxies. The implications of these measurements for cosmology, supernovae history, star formation and AGN heating will be assessed with numerical simulations. We request observations of 10 unobserved groups in our sample

Proposal Number: 08800952

Title: A Complete Baryon Census in a Nearby Galaxy Group

PI Name: John Mulchaey

We propose an ACIS-I mosaic of the NGC2563 group to study the X-ray properties of the group galaxies out to the virial radius of the system. The proposed observations will provide important observational constraints on the mechanisms that drive galaxy evolution in groups by allowing us to study how the properties of galaxies vary with distance from the group center, IGM and galaxy density. The Chandra data will allow us to study the hot ISM halos of individual galaxies as well as the more extended intragroup medium component, which combined with our existing optical and HI data will provide a complete census of all of the major baryonic components in the group.

Proposal Number: 09800310

Title: Probing Dark Energy with Relaxed Galaxy Clusters

PI Name: Steven Allen

We seek to constrain dark energy using studies of the apparent evolution of the X-ray gas mass fraction in the most X-ray luminous, dynamically relaxed galaxy clusters. The proposed observations will improve the detection of the effects of dark energy from the X-ray data alone to > 5 sigma. More importantly, they will allow us to measure the level of intrinsic (systematic) scatter in distance measurements from this technique and establish whether this is smaller than from type Ia supernovae measurements. Used in combination with supernovae and CMB data, the new Chandra observations will allow the most precise search to date for evolution in the dark energy equation of state - our best approach in trying to understand the origin of cosmic acceleration.

Proposal Number: 09800847

Title: BOW SHOCK, ELECTRON-ION EQUILIBRIUM, BREAKUP OF COOL CORE, AND DARK SUBCLUSTER IN ABELL 520

PI Name: Maxim Markevitch

Shock fronts provide a unique tool to study the cluster plasma. Only two have been found, those in 1E0657 and A520. Using a long observation of 1E0657, we have determined, for the first time in any astrophysical plasma, that electron-proton equilibration time is shorter than Coulomb - a tantalizing result but based on one object. A520 gives the only chance to confirm it. Its shock also coincides with an edge of the radio halo, enabling tests of the origin of the intracluster relativistic electrons. A520 also exhibits a remnant of a cool core broken up by merger-induced instabilities, providing data on plasma viscosity. Finally, weak lensing map of A520 reveals an intriguing dark subcluster almost devoid of galaxies. We propose a long observation of this exceptionally interesting cluster.

Proposal Number: 10800641

Title: A Deep Image of the Most Powerful Cluster AGN Outburst

PI Name: Brian McNamara

Powerful AGN outbursts in galaxy clusters can release upward of 1E61 erg into the intracluster medium. Events of this magnitude are able to quench cooling flows and drive large-scale outflows that redistribute and heat the gas on cluster-wide scales. The most potent example of this is seen in the z=0.22 cluster MS0735.6+7421, whose powerful shock and cavity system have injected an estimated 6E61 erg of energy into the ICM. We propose to obtain a 500 ksec ACIS image of the cluster to examine in detail the relationships between the shock, cavity, and radio systems, and to investigate the impact of powerful AGN outbursts on the structure of the cluster.

Proposal Number: 10800762

Title: The Role of AGN in Massive Galaxy Formation

PI Name: Spencer Stanford

There is increasing evidence that high rates of star formation in massive galaxies was common in rich environments at z > 1. The leading candidate for quenching the star formation and transforming cluster galaxies into red sequence galaxies is AGN. Therefore we expect to see an increase in AGN incidence in dense environments at z > 1. We propose to systematically determine the incidence of AGN in galaxy clusters at 1 < z < 1.5 using moderately deep ACIS imaging of IR-selected clusters in the Bootes field. In conjunction with extensive data from Spitzer, HST, and Keck, we will test the AGN quenching paradigm for the origin of the stars in massive galaxies.

Proposal Number: 10800779

Title: Shocks, Ripples, and Bubbles: A Very Deep Observation of Abell 2052

PI Name: Elizabeth Blanton

The cooling flow cluster A2052 has, arguably, the morphology most similar to the Perseus cluster as seen with Chandra. Two clear bubbles to the N and S of the center of A2052 are filled with the radio lobes associated with 3C 317. Surface brightness discontinuities consistent with shocks with Mach numbers of 1.8 and 1.2 are seen near the cluster center. These may be isothermal shocks. We propose to observe Abell 2052 much more deeply to study these shock features, ripple features due to sound waves that may be found at larger radii, possible ghost bubbles, cooling gas in the bright shells around the radio source that may link the X-ray and H-alpha emission, and possible hot gas within the X-ray holes. We will directly compare the star formation and cooling rates in the cluster center.

Proposal Number: 11800102

Title: Extending the Deep Image of the Perseus Cluster: The Outer Bubbles, Filaments and Ripples

PI Name: Andrew Fabian

Our existing 900ks image of the core of the Perseus cluster has revealed a wealth of detail on the bubbles, shocks and ripples caused by the action of the central AGN on the surrounding ICM. Most of the advances are directly due to the high surface brightness of the Perseus cluster (higher than any other cluster) and to the high spatial resolution of Chandra. This resolution is degraded significantly 4 arcmin or more off-axis, meaning that the region studied at the highest resolution is quite small. Here we propose three further exposures totalling 700ks to extend the highest resolution region, covering areas to the N and S of the nucleus where the current data suggest the presence of further intriguing and important structures due to the AGN activity.

Proposal Number: 11800471

Title: Chandra Observations of a Complete Sample of SZE Selected Galaxy Clusters

PI Name: Joseph Mohr

We propose to obtain X-ray observations of a complete sample of 16 SZE selected galaxy clusters from the South Pole Telescope (SPT) survey. The SZE selection produces an approximately mass limited sample (at all redshifts) over the existing 200 deg^2 SPT survey. The Chandra observations provide X-ray mass estimates and morphologies, allowing (1) an initial calibration of the SZE flux-mass relation and (2) early tests of cosmology and the evolution of structure. Our 346ks request leverages 625ks of GTO time in AO10/11; these X-ray data are crucial to developing an understanding of the new window on the universe that SPT has opened and in laying the foundation for future studies using the full SPT survey (~1400deg^2 by 2010).