Program
Rasmuson Theater
- Tuesday October 6, 2015
- 8:00-4:00
- Registration (Rasmuson Theater) and Poster Installation (Rooms 4018 and 4019)
- OPENING TALKS
- Chair: Martin Weisskopf
- 9:00-9:10
- 9:10-9:40
Keynote
Forthcoming
- 9:40-10:10
X-Ray Surveyor Mission Concept
An initial concept study for the X-ray Surveyor mission was carried-out by the Advanced Concept Office at Marshall Space Flight Center (MSFC), with a strawman payload and related requirements that were provided by an Informal Mission Concept Team, comprised of MSFC and Smithsonian Astrophysics Observatory (SAO) scientists plus a diverse cross-section of the X-ray community. The study included a detailed assessment of the requirements, a preliminary design, a mission analysis, and a preliminary cost estimate. The X-ray Surveyor strawman payload is comprised of a high-resolution mirror assembly and an instrument set, which may include an X-ray microcalorimeter, a high-definition imager, and a dispersive grating spectrometer and its readout. The mirror assembly will consist of highly nested, thin, grazing-incidence mirrors, for which a number of technical approaches are currently under developmentâincluding adjustable X-ray optics, differential deposition, and new polishing techniques applied to a variety of substrates. This study benefits from previous studies of large missions carried out over the past two decades, such as Con-X, AXSIO and IXO, and in most areas, points to mission requirements no more stringent than those of Chandra.
- 10:10-10:40
Capabilities and Science Drivers for the X-ray Surveyor Mission
The X-ray Surveyor mission concept is designed to make dramatic increases in discovery space and science capabilities for X-ray astronomy. These would be accomplished through orders of magnitude improvements over Chandra in sensitivity, field of view for sub-arcsec imaging, effective area for grating spectroscopy, and by providing high spectral resolution capabilities for extended objects on 1-arcsec angular scales. An X-ray observatory with such capabilities, operating in concert with other major astronomical facilities of the 2020-2030s, is required to address and solve some of the greatest challenges in modern astrophysics. The X-ray Surveyor will shed light on the formation of supermassive black holes by being able to detect X-rays from these objects as they grow beyond their seed state in the first galaxies. Direct data on the nature and operating modes of feedback will be provided by characterizing hot gas in galaxies and groups on scales from the very near vicinity of the central black out to the virial radius. A new era in our understanding of the plasma physics effects on astrophysical scales will be opened, for example, by resolving the detailed structure of relativistic shocks in pulsar wind nebulae and the gas turbulence in galaxy clusters. The detailed structure of the Cosmic Web will be exposed for the first time by mapping X-ray emission from hot gas in its filaments. The outstanding capabilities of X-ray Surveyor will make it an indispensable research tool in nearly every area of astrophysics.
- 10:40-11:00
- Coffee Break
- SESSION 1: COMPACT OBJECTS: NEUTRON STARS AND THE BIRTH AND EVOLUTION OF BLACK HOLES
- Chair: Chryssa Kouveliotou
- 11:00-11:25
The First Black Holes: Formation and Detection
I will present a status report of our understanding of the formation of the first black holes at high redshift in the universe including the current open questions. The mechanisms that produce the seed black holes; their potential growth histories; observable properties and detectability with future X-ray and Optical/IR missions will be discussed.
- 11:25-11:50
X-ray Emission from Star Formation at Earlier Times in the Universe
X-ray emission from star formation is a critical source of energy input into the primordial z10 Intergalactic Medium IGM, and is now emerging in many papers on high-z 21 cm measurements of the IGM as a parameter of great interest. The deepest X-ray survey of the distant Universe, the 7 Megasecond Chandra Deep Field-South, reaching completion in Fall 2015, allows us to view the X-ray emission from star-forming galaxies out to very early times in the universe z3-4. Combining these extremely deep Chandra exposures with the best available local Universe constraints and theoretical binary population synthesis modeling, we have now demonstrated fairly robust predictions of the level of X-ray emission expected at the epoch of Cosmic Dawn z10-20. This permits us to predict what we might see at those redshifts with X-ray Surveyor.
- 11:50-12:15
Binary Black Hole Accretion
Supermassive black hole binary mergers in the presence of gaseous accretion flows and are prime candidates for simultaneous observations of both gravitational waves and electromagnetic signals. I will present the results of 2D hydrodynamical simulations of circum-binary accretion disks using our new moving-mesh code DISCO. These simulations demonstrate that gas accretion is not impeded by binarity as had been previously predicted. Rather, gas is efficiently stripped from the inner edge of the circum-binary disk and enters the cavity along accretion streams, which feed persistent mini-disks surrounding each black hole. I will discuss characteristic periodicity in the measured accretion rate onto each BH, with implications for the quasar PG 1302-102 which has recently shown evidence for periodic variability. I will also discuss the dependence of the accretion flow on the binary mass ratio and characteristic modifications to the spectrum which arise from shock heated gas inside the circum-binary cavity. Finally, I will discuss simulations which include binary inspiral and merger due to gravitational wave emission in order to track the changes in accretion and electromagnetic radiation as the orbit shrinks.
- 12:15-12:40
High Resolution Deep X-ray Surveys: A Unique Probe of the High-Z Universe
Understanding the origin and growth of the supermassive black holes SMBHs that lie at the centers of most, if not all, galaxies at all redshifts is crucial for obtaining the full picture of both BH and galaxy evolution. Enormous progress has been made in the understanding of the galaxy population in the Universesfirst few Gyrs. On the contrary, there is still the puzzle that giant SMBHs already exist at z=6-7, implying massive seed black holes or highly super-Eddington accretion at the earliest times. This is because the search for z6 Active Galactic Nuclei i.e., accreting SMBHs is still limited to the optically selected sources from the SDSS or CFHQS surveys, which probe the unobscured accretion.Instead, X-ray surveys can probe the obscured high-z, low mass population, which represent the bulk of rapid early SMBH growth, and are therefore essential for obtain an unbiased sample of the accreting SMBHs. I will present the most recent results on the high redshift Universe as we know it from the current Chandra X-ray surveys and discuss what we can expect from planned and proposed future X-ray observatories. High spatial resolution is crucial to locate faint X-ray sources and identify their counterpart in future deep optical images. Increasing the surveys sensitivity to the limits allowed by the X-ray Surveyor, we will be able to collect sizable samples of z6 low luminosity and low mass AGN to study their early growth. Comparison with galaxy formation and evolution at similar redshift will provide the means to understand the SMBH-galaxyrelation at the earliest epochs.
- 12:40-12:45
Disentangling the Quasars X-ray Emission Regions with Microlensing.
As accreting supermassive black holes, AGNs are among the most physically interesting objects in the Universe. They also help to regulate star formation and the evolution of galaxies. One of their defining characteristics is their X-ray emission, but the origin and spatial extent of this emission is still unknown in large part because we have lacked the means to resolve the central engine. However, microlensing in multiply imaged gravitationally lensed quasars allows us to zoom in on in the structure of AGN and explore their physics in more detail. Quantitative microlensing X-ray size constraints exist for 6 systems, setting the first upper limits for these emitting regions. Obtaining these pioneering results was possible due to the high resolution and sensitivity of the CXO. The next frontier is to explore possible correlations of the X-rays sizes with black hole mass and spectral index, as well as to set constraints on the scaling of the size with X-ray energy. In my talk I will briefly describe our methodology and results, and discuss the key aspects of X-ray Surveyor that would help us to obtain unprecedented results in the field.
- 12:45-12:50
A New Window in our Understanding of X-ray Binaries
Populations of extragalactic X-ray binaries are an invaluable tool for studying the formation and evolution of compact objects in binary stellar systems. Despite their systematic study for 50 years since their discovery, several key questions related to their formation and evolution are still unanswered. One of these questions is the formation rate of accretion binaries as a function of age of stellar populations, and as a function of their metallicity and environment. This is key for understanding the cosmological evolution of compact object populations and their impact in galaxy evolution through feedback. The X-ray Surveyor will provide a major leap in this field by providing a census of even quiescent accreting binaries in the Local Group, a complete census of all active X-ray binaries Lx 10E36 erg/s out to a radius of 50Mpc. These, in combination with the detection of luminous Lx10E39 erg/s individual X-ray sources out to cosmological distances will provide the ultimate direct calibrations of X-ray binary formation rates, and constrain accreting binary formation and evolution models in the local and distant Universe, providing more accurate constraints on the populations of compact objects and their importance as feedback agents.
- 12:50-1:10
- Discussion
- 1:10-2:10
- Lunch
- SESSION 1 CONTINUED: COMPACT OBJECTS: NEUTRON STARS AND THE BIRTH AND EVOLUTION OF BLACK HOLES
- Chair: Belinda Wilkes
- 2:10-2:35
AGN Feedback in the X-ray Surveyor Era
It is now widely recognized that the growth of supermassive black holes can have a profound influence on the evolution of their host galaxy. For example, powerful quasars resulting from the merger of gas rich galaxies can produce sub-relativistic winds that may expel cold gas from the galaxy, extinguishing continued star formation. Another form of feedback occurs in giant elliptical galaxies and galaxy clusters - relativistic jets from the central AGN appear to heat the hot interstellar/intracluster gas, preventing a cooling catastrophe that would otherwise grow the stellar mass appreciably. While current observations reveal incontrovertible signatures of these feedback processes, the underlying physical mechanisms remain very poorly understood. What drives the powerful winds in luminous quasars? How does the energy injected by relativistic jets actually become thermalized in the intracluster medium? How are the feedback loops maintained? In this talk, I will discuss these questions and the impact of future observations by Astro-H, ATHENA and the X-ray Surveyor.
- 2:35-3:00
Impact of the X-ray Surveyor on Supermassive Black Hole Spin Measurements
The past decade has seen remarkable progress in the field of measuring angular momentum in supermassive black holes: we now have roughly 25 AGN whose SMBHs have robust, published black hole spin constraints. Though this is a fine achievement by the collective observations of Chandra, XMM-Newton, Suzaku and NuSTAR, much work remains to be done. In particular, we must refine the precision and accuracy of the spin measurements we do have and expand the population of AGN with measured SMBH spins. Such an endeavor requires, principally, an instrument with enhanced collecting area relative to current observatories, particularly in the 2-10 keV range, as well as superb spectral and spatial resolution. I will discuss how the X-ray Surveyor concept could contribute to SMBH spin research, especially in terms of revealing fainter populations of AGN than have previously been able to be utilized for this study.
- 3:00-3:25
Spectroscopy of Black Hole Outflows
Outflows from systems containing black holes are widespread and have major implications for these systems and for their surroundings. X-rays are the natural way to explore most of these outflow. I describe how improved X-ray spectroscopy such as that provided by X-ray Surveyor could transform our understanding of these questions.
- 3:25-3:50
X-ray Photoexcited Extranuclear Gas in Active Galaxies
I will present a summary of results from 16 years of high resolution X-ray spectroscopy of gas in the neighborhood of Active Galactic Nuclei. Led by the prototypical Sy 2 galaxy NGC 1068, we now have many examples of circumnuclear gas that is excited by the central source. In galaxies with obscured nuclei, the gas is rich with emission lines from highly ionized species and radiative recombination continua. Outflows are apparent and several cases are resolved at the 1-5 level. The ionization models give velocity, density, and composition diagnostics. These outflows carry significant energy and momentum, affecting the energy budget of the local intergalactic medium. The X-ray Surveyor can examine the prevalence and impact of these ionization cones in the z1 universe.
- 3:50-3:55
A Synoptic View of Accretion Disk Winds from Stellar-Mass Black Holes
In the last decade, Chandra, XMM, and Suzaku observations of X-ray binaries have revealed that accretion disk winds play a key role in black hole accretion physics, exemplifying feedback on many time scales and regulating the accretion rate at the event horizon. We have focused on using photoionization diagnostics to determine the physical origin of winds, but these diagnostics tend to be informative rather than definitive. With the X-ray binary GRO J1655-40 as an illustrative example, I will argue that in order to make substantial progress on the physics of winds, we require a multifaceted approach -- incorporating not only high resolution line spectra and photoionization models but also accurate continuum spectroscopy, timing analysis, and coordinated multiwavelength data. With its excellent spectral resolution and sensitivity, the X-ray Surveyor will provide next-generation insights into the geometry, dynamics, variability, and the astrophysical significance of disk winds from stellar-mass black holes.
- 3:55-4:15
- Discussion
- 4:15-4:35
- Coffee Break + Poster Session, Rooms 4018 and 4019
- 4:35-5:00
Neutron Star Science with the X-ray Surveyor
Probing the interiors and magnetic fields of neutron stars and characterizing their populations in the Galaxy is an important science goal for the next generation X-ray telescopes. I will discuss how the capabilities of the X-ray Surveyor Mission are crucial for making significant advances in these fields and how we can address the open questions with a dataset that will become available with such a mission.
- 5:00-5:25
X-ray AGN in the Cluster Environment
X-ray AGN surveys suffer little contamination, low absorption bias and provide direct access to most of the accretion power in the Universe. However, studies of AGN in clusters suffer from small sample sizes. We recently undertook a survey of X-ray AGN in the fields of 135 massive clusters and found the number density of AGN at r500 scales inversely with cluster mass in a similar way to the predicted galaxy merger rate. Our statistical technique sidesteps the need for expensive optical follow-up, and allows us to exploit the longest possible lever arms in cluster radius, mass and redshift. Measurements with X-ray Surveyor using similar techniques will allow us to trace the evolution of AGN in dense environments from early-times, through the peaks of AGN and SF activity, to the present day.
- 5:25
- Break for Dinner
- Wednesday October 7, 2015
- SESSION 2: PLASMA PHYSICS
- Chair: Steve Allen
- 9:00-9:25
Diffuse Hot Gas in Galaxy Clusters at High Spatial and Spectral Resolution
Forthcoming
- 9:25-9:50
Microphysics of Intracluster Plasma with a High Angular Resolution Microcalorometric Array
Our usual assumption of the Maxwellian distribution for thermal electrons in the intracluster plasma may be incorrect, as evidenced by observations in the solar wind plasma. Strong deviations are possible, and even likely, in cluster locations where cosmic ray acceleration should be occurring as seen from the resulting synchrotron radio emission, such as radio halos and relics. Recent theoretical work shows that such non-Maxwellian electron distributions would alter the ionization balance and emission line ratios for various elements, and even the shape of thermal continuum that we use for cluster temperature determination. To find evidence for such deviations at cluster shock fronts and radio relics, an instrument with 1 arcsec, 1 eV resolution and a large collecting area is required.
- 9:50-10:15
Galaxy Cluster Gas Motions with X-ray Surveyor: Probing the Small Scales
The advent of X-ray microcalorimeters will provide the opportunity for the first time to measure plasma motions in galaxy cluster. In anticipation of Astro-H, I have carried out a simulation-based investigation of turbulence and gas sloshing in the intracluster medium, using simulated observations to make precise predictions for what Astro-H will be capable of observing. In this talk, I will discuss how the improved angular resolution and effective area of the X-ray Surveyor mission will help to improve on these achievements. In particular, I will show how X-ray Surveyor will place tighter constraints on the viscosity of the cluster plasma and enable more precise modeling of the gas velocity field.
- 10:15-10:40
Measuring Effective Equation of State of Diffuse Gas in Galaxy Clusters: From Chandra to X-ray Surveyor
Density perturbations in the hot gas in galaxy clusters can be caused by a variety of processes, e.g. shocks and sound waves, slow gas displacements in pressure equilibrium with the ambient gas, bubbles of relativistic plasma, etc. Each type of perturbations will appear different in soft- and hard-band X-ray images, since the former is only density-dependent, while the latter is also temperature-dependent. High spatial resolution of Chandra allows us to probe statistics of density perturbations on a broad range of spatial scales, down to microphysical scales. I will show the results of auto- and cross-spectra analysis of fluctuations in soft and hard bands in the core of the Perseus cluster which reveal the primary energy-transporting mechanism in the radio-mode feedback. The analysis shows big potential, although low photon statistics and lack of high-spectral-resolution data significantly limit the analysis. Future X-ray missions with large effective area, similar to Chandra spatial resolution and few eV spectral resolution, like X-ray Surveyor, will allow us to use the whole power of such statistical methods. At the end of my talk I will briefly discuss future perspectives with X-ray Surveyor.
- 10:40-10:45
Studying the Turbulent Dynamics of the ICM in Galaxy Clusters by Using the High Spectral and Spatial Resolutions of the X-ray Surveyor
Observations of turbulence in the ICM of galaxy clusters would provide important answers regarding cluster mergers,quiescent gas accretion, intra cluster magnetic field generation, and the roles of turbulent pressure and turbulent heating in cluster structure. Since the gas is at temperatures exceeding KeV, one needs:1. High spectral resolution observations of X Ray lines2. High spatial resolution so that a power spectrum can be obtained.The obtained power spectrum could be combined with Radio rotation measure observations in the cluster, as to study the relation between the turbulence and the magnetic field.This could provide clues whether the magnetic field originates in the stripped galaxies or is at least modifiedand amplified due to turbulent amplification.For turbulence resulting from clusters merger the turbulent velocity on the large scale is estimated to be of the order of few, e.g. 200 km/s,and the largest scale is estimated as 0.2 kpc. In order to measure a power spectrum one needs to measure velocities on scales down to about 10 pc. The expected turbulent velocity on this scale for compressible turbulence is 200 SquarRoot10/500= 28 km/s.The required spectral resolution is thus 0.03, and the spatial resolution required for resolving 10 kpc a galaxy cluster at a 100 Mpc distance is about 2 arcs.Both requirements are met by the X-Ray Surveyor.
- 10:45-10:50
Probing the Physics of Particle Acceleration in Dilute Cosmic Plasmas
In a growing number of galaxy clusters diffuse elongated radio sources have been found, so-called radio relics. These megaparsec relics are usually located in the low-density outskirts of merging clusters. The existence of these radio sources implies the presence of relativistic particles and magnetic fields in the intracluster medium. The idea is that these radio relics trace cluster merger shocks, where particles are accelerated to relativistic energies, causing them to emit synchrotron radiation observable at radio wavelengths. However, a problem is that cluster merger shocks should have low-Mach numbers, for which particle acceleration is thought to be very inefficient. This is hard to reconcile with the observed synchrotron radiation. Current X-ray observations lack the sensitivity to determine accurate shock properties, since these relics are located in the faint outskirts of clusters. Observations with the X-Ray Surveyor will for the first time provide accurate measurements of the Mach number of these shocks, both using the temperature and surface brightness. This will provide crucial information to determine the nature of the particle acceleration mechanism that operates this intracluster plasma.
- 10:50-11:05
- Discussion
- 11:05-11:25
- Coffee Break + Poster Session, Rooms 4018 and 4019
- SESSION 2 CONTINUED: PLASMA PHYSICS
- Chair: Rob Petra
- 11:25-11:50
Supernova Remnants in High Definition
As the observable products of explosive stellar death, supernova remnants reveal some of the most direct information on the physics of the explosions, the properties of the progenitor systems, and the demographics of compact objects formed in the supernova events. High sensitivity X-ray observations have allowed us to probe the properties of the shocked plasma, providing constraints on abundances and ionization states that connect directly progenitor masses and metallicities, the nature of the explosions (core-collapse vs. thermonuclear), and the physics of shock heating and particle acceleration in fast shocks. Studies of SNRs in the Magellanic Clouds have provided information on source demographics in a low metallicity environment, and deep searches for point sources in Galactic SNRs imply that many remnants contain rapidly cooling neutron stars or black holes. Based on Chandra observations, we know that crucial measurements required to advance our knowledge in these areas are possible only with much more sensitive observations at high angular resolution. From identifying the effects of particle acceleration on the post-shock gas in young SNRs like Tycho to obtaining spatially resolved spectra - and identifying compact objects - for young SNRs in the Magellanic Clouds, the capabilities of a facility like the X-ray Surveyor are required. Here I present a summary of recent advances brought about by spectral investigations of SNRs, and discuss particular examples of new advances that will be enabled by X-ray Surveyor capabilities.
- 11:50-12:15
X-ray View of Pulsar Wind Nebulae: What Chandra Did Not Tell Us
Observations with Chandra X-ray observatory have significantly advanced our understanding of pulsar windsand pulsar wind nebulae PWNe. Deep, high-resolution imaging in X-rays reveals the fine structure of PWNe, such as termination shocks in the equatorial wind, polar jets with moving knots, cometary-shaped bow shocks, and more complex structures seen on different scales. The spatially-resolved X-ray spectroscopy enabled measurements of the particle injection spectrum in the vicinity of the termination shock. Deep observations also probe the spectral evolution as a function of distance from the pulsar. Multiple observations of the same PWNe have demonstrated that the PWNe can also be highly variable. I will review most recent results and discuss the current limitations to PWN studies.
- 12:15-12:20
Waves at Oblique Shocks and the Highest Cosmic Ray Energies in Tychos SNR
We describe a new model for the stripes of synchrotron radiation seen in the remnant of Tychos supernova, in terms of Alfven wave generation by the Bell Instability, followed by reflection, refraction and damping at an oblique shock. Based on estimates for damping rates due to turbulent cascade and transit time damping, we estimate the dependence of the visibility of the stripes on the shock obliquity, and determine a maximum cosmic ray energy in Tychos SNR in the range 6 x 1014 - 1 x 1015 eV, close to the knee in the cosmic ray spectrum. With such an understanding, synchrotron stripes ought in principle to be more commonly seen in SNRs, and should constitute a prime science topic for any future X-ray astronomy observatory.
- 12:20-12:40
- Discussion
- 12:40-1:40
- Lunch
- SESSION 3: CYCLES OF BARYONS
- Chair: Peppi Fabbiano
- 1:40-2:05
Feedback with X-ray Surveyor
Forthcoming
- 2:05-2:30
Exploring Galaxy Halos and the Cosmic Web through X-Ray Spectroscopy
About 90 of the metals produced in the universe and 50 of the baryons are unaccounted for through UV-IR and radio studies of stars and gas. This large amount of gas and metals likely lies in a hot phase 0.5-10E6 K and must be enriched to about 0.2-0.3 of the solar metallicity, so it should be a good absorber of X-rays in the resonance lines of common elements. X-ray absorption lines against background AGNs should show hot extended halos around galaxies out to the virial radius, if not beyond. The outer parts of galaxy groups and some cosmic filaments are other potential sources of absorption. For the Milky Way, high X-ray spectral resolution allows us to determine the dynamics of the hot halo, including the rotation as a function of radius as well as the accretion or outflow rate.
- 2:30-2:55
Constraining Galaxy Formation with Gaseous Halos
I will present arguments for the strong need of observational probes of gaseous halos of galaxies.
- 2:55-3:20
Precipitation-Regulated Galaxies
I will outline a framework for the regulation of star formation in high-mass galaxies that has been motivated by X-ray observations. According to this framework, feedback regulates star formation by suspending the circumgalactic medium CGM in a state of marginal thermal instability, which links a galaxys star-formation rate and central black-hole mass with the cooling rate of the CGM. One of the key test of this framework will be the diffuse X-ray luminosity function of galaxies, which can be measured by the X-ray surveyor.
- 3:20-3:40
- Discussion
- 3:40-3:50
- Coffee Break
- 3:50-5:15
- Breakout
Brainstorming Session, Room 4025
Session Summary - 5:15
- Break for Dinner
- Thursday October 8, 2015
- SESSION 3 CONTINUED: CYCLES OF BARYONS
- Chair: Mike Nowak
- 9:00-9:05
Hot Coronae Around Spiral Galaxies: Probing the First Principles of Galaxy Formation
The presence of hot gaseous coronae in the dark matter halos of massive spiral galaxies is a fundamental prediction of all structure formation models. Yet these coronae remained unexplored for several decades, thereby posing a serious challenge to observers and theorists. Although several X-ray coronae have been detected around nearby massive spiral galaxies in the past few years, we still lack a comprehensive picture. X-ray Surveyor will provide the much needed breakthrough. Specifically, X-ray Surveyor will characterize the hot coronae in unprecedented details, explore their evolution as a function of redshift, which in turn will constrain the physical processes that play an essential role in galaxy formation from the early Universe to the present epoch.
- 9:05-9:10
High Resolution X-Ray Absorption Spectroscopy: Distribution of Matter in and around Galaxies
The chemical evolution of the Universe embraces aspects that reachdeep into modern astrophysics and cosmology. We want to know how presentand past matter is affected by various levels and types of nucleo-synthesisand stellar evolution. Three major categories were be identified:1. The study of pre-mordial star formation including periods of super-massive black hole formation,2. The embedded evolution of the intergalactic medium IGM.3. The status and evolution of stars and the interstellar medium ISM in galaxies.Today a fourth category relates to our understanding of dark matter in relationwith these three categories.The X-ray band is particularly sensitive to K- and L-shell absorptionand scattering from high abundant elements like C, N, O, Ne, Mg, Si, S,Ar, Ca, Fe, and Ni. Like the Lyman alpha forest in the optical band, absorbersin the IGM produce an X-ray line forest along the line of sight in the X-rayspectrum of a background quasar. Similary bright X-ray sources within galaxiesand the Milky Way produce a continuum, which is being absorbed by elements invarious phases of the ISM.High resolution X-ray absorption surveys are possible with technologies readyfor flight within decade. == high efficiency X-ray optics with optical performance 3== high resolution X-ray gratings with R 3000 for E 1.5 keV== X-ray micro-calorimeters with R 2000 for E 1.5 keVThe vision for the next decade needs to lead to means and strategies which allows us to perform such absorption surveys aseffectively as surveys are now or in very near future quite common inastronomy pursued in other wavelength bands such as optical, IR, and sub-mm.
- 9:10-9:15
Probing the Radio Mode AGN Feedback Cycle in the X-ray
Despite the strong empirical evidence that feedback from radio AGN active galactic nuclei regulates the growth of the most massive galaxies, we are far from understanding how this feedback cycle operates. Feedback models generally require an AGN to be fueled by cooled or cooling gas, with accretion of cooled gas being favored by current theory and observations. However, there is little direct evidence of hot gas cooling to low temperatures. I will discuss how X-ray observations at high spatial and spectral resolution, as could be provided by an X-ray Surveyor mission, can be used to probe feedback between a radio AGN and its hot atmosphere. My primary focus will be on thermally unstable cooling of the hot gas, but I will also consider aspects of energy transfer to the gas.
- 9:15-9:40
The Next Frontier of High-Redshift Massive Galaxies and Quasars
- SESSION 4: PHYSICS OF NEW WORLDS
- Chair: Martin Laming
- 9:40-10:05
Coronal Spectroscopy for Dynamo Studies
Magnetic reconnection lies at the heart of much stellar phenomena in the cool half of the H-R diagram, and X-ray studies of stellar coronae have revealed the intricate interplay of plasma and magnetic fields, ultimately produced as the result of a dynamo process. The breakthrough of Chandra and XMM-Newtons high resolution spectrometers for these stars lay in revealing the wealth of diagnostic information, used to demonstrate the structuring and energetics of hot plasma, and the extent to which magnetic fields shape and influence stellar surroundings. In this talk I will describe how high resolution, high throughput spectra with the XRS continue the challenge of linking a well-studied star like our Sun with representative stellar samples to probe dynamos in the stellar extremes of thick/thin outer convection zones, and time-varying influences of magnetic fields.
- 10:05-10:30
Probing the Physics of Exoplanet Systems with X-ray Observations
Exoplanetary systems have been detected in a wide variety of orbital architectures, many of them different from what we observe in our own solar system. For example, exoplanets have been found to orbit their host stars at extremely close distances, or in highly eccentric orbits. This leads to physical phenomena like extended exoplanetary atmospheres, planetary mass-loss through atmospheric evaporation, or magnetic and tidal interactions between the star and its near-by planets. X-ray observations provide a new observational window to these processes, and exploratory programs with current X-ray observatories have already yielded fascinating glimpses of star-planet phenomena. I will discuss how observations with high sensitivity and energy-resolution at soft X-rays will lead to a new understanding of the physical processes between exoplanets and their host stars.
- 10:30-11:10
- Discussion
- 11:10-11:35
- Coffee Break + Poster Session, Rooms 4018 and 4019
- SESSION 5: ISM & STAR FORMATION IN THE LOCAL GROUP
- Chair: Ann Hornschemeier
- 11:35-12:00
The Future of our Past: Star Formation and Feedback with X-ray Surveyor
Chandra has shown that star formation study -- the bedrock of Cosmic Origins -- sits squarely in the realm of high-energy astrophysics. X-ray emission efficiently distinguishes young stars from unrelated field stars and shows us the birth of the hot ISM in the feedback of massive stars. X-ray Surveyors sensitivity, large FoV, and compact PSF over wide fields will supercharge the science of star formation, from hypercompact HII regions barely able to resist collapse to superbubbles so large that they shape our views of galaxies. It will X-ray the bones of the Milky Way and untangle Young Massive Clusters, the star formation powerhouses we see across the Local Group. Here we will explore a few ideas for the future of understanding our past through X-rays.
- 12:00-12:25
The Galactic Center: Science Frontiers Accessible to the X-ray Surveyor
In this overview talk, I will address the numerous frontiers presented by the Galactic center region that can be profitably explored with the X-ray Surveyor.The talk will include the following topics: 1. the central black hole and its resolvable accretion flow, 2. the profusion of stellar X-ray sources and their spatial distribution, including both low and high-mass stars,3. the expanding front of fluorescent X-rays indicative of a past powerful energy release, likely from the Galactic black hole, 4. linear X-ray filaments associated with magnetically organized, non-thermal radio filaments, and 5. the nature and the origin of the diffuse X-ray emission that permeates the central few hundred parsecs of the Galaxy.
- 12:25-12:50
Studying Interstellar Dust Grain Composition with High Resolution Spectroscopic Imaging
Interstellar dust in the foreground of bright point sources will scatter X-rays over arcminute scales, producing a diffuse halo image. The scattering halo intensity is strongly sensitive to the dust grain size distribution, spatial distribution, and composition of dust on the sight line. Currently, Chandras spatial resolution makes it the best detector available for studying X-ray scattering halos from the diffuse ISM. A Chandra successor with similar resolution but larger effective area will lend a greater opportunity to study scattering echoes from low column densities of the diffuse interstellar or intergalactic medium. More importantly, the combination of high resolution spectroscopy with imaging is uniquely suited to studying the composition of dust grains. At soft energies in particular, the spectrum of scattered light is likely to have significant features at the 0.3 keV C-K and 0.5 O-K photoelectric absorption edges. This direct probe of ISM dust grain elements will be important for i understanding the relative abundances of graphitic grains or PAHs versus silicates, and ii measuring the depletion of gas phase elements into solid form.
- 12:50-1:30
- Discussion
- 1:30-1:45
- Concluding Remarks