Chandra Large and Very Large Projects

Proposal Number: 02500880

Title: COORDINATED CHANDRA/HST OBSERVATIONS OF THE CRAB NEBULA

PI Name: JEFF HESTER

Recent monitoring of the Crab Nebula with the HST and Chandra sheds new light on both the structure and dynamics of the region into which the wind from the Crab pulsar flows. Bright X-rays predominately originate in regions which contain sharp and highly dynamic structure at visible wavelengths, reflecting the short synchrotron lifetime of the most energetic particles in the nebula. We now have a unique opportunity for an intensive coordinated optical/X-ray campaign to study this dynamic structure. We have an approved and scheduled HST program to monitor the Crab at 11-day intervals during 8 months in the 2000-01 observing season. We request sixteen 25 ks observations with the Chandra ACIS to monitor the X-ray structure and spectrum of Crab during the HST campaign.

Proposal Number: 03500538

Title: A CHANDRA SURVEY FOR COMPACT OBJECTS IN SUPERNOVA REMNANTS

PI Name: Shrinivas Kulkarni

It has become increasingly clear that the natal properties of young neutron stars exhibit a rich diversity --- dramatically illustrated by the enigmatic central object in Cas A and hinted at by early 3D modeling of core-collapse. We propose a survey of an objectively constructed sample of nearby SNRs which, when combined with archival data and our vigorous multi-wavelength observation program, will give us a reliable view of the true variety of neutron stars. The ensuing statistics and studies of the central objects will advance our understanding of core-collapse and have bearing on related topics (supernova energetics, natal kicks, etc). We believe that this comprehensive effort, a census of such objects within 5 kpc, will be one of the enduring legacies of the Chandra mission.

Proposal Number: 04500141

Title: A DETAILED STUDY OF 3C58 - THE YOUNGEST KNOWN PULSAR NEBULA IN THE GALAXY

PI Name: Patrick Slane

3C58 is the youngest known Crab-like SNR in the Galaxy. Chandra observations have uncovered its young pulsar, provided an upper limit to its surface temperature which challenges standard models of NS cooling, and identified the termination shock of its wind. Structures in the nebula indicative of jets and particle outflows have also been revealed. 3C58 thus possesses all of the standard traits of a young pulsar system, and may be a more appropriate "prototype" than the Crab. Based on the foundation built from our initial studies, we propose a definitive X-ray study of 3C58 to study structure on scales of the telescope resolution, perform spectral mapping of the complex emission regions, and obtain a template for future studies of this remnant of SN 1181 at other wavelengths.

Proposal Number: 04500223

Title: STUDYING HIGH MACH NUMBER SHOCKS IN YOUNG SUPERNOVA REMNANTS WITH CHANDRA

PI Name: John Hughes

We propose deep imaging of the full extents of the young supernova remnants SN1006, Tycho, and G292.0+1.8. These images are optimized for proper motion measurements for which Chandra's superb angular resolution is uniquely suited and will yield significant results when compared to earlier Chandra, ROSAT, and Einstein images. The new X-ray data, in conjunction with our new radio observations, will address questions concerning the physics of ultra-high-Mach-number collisionless shocks, the efficiency of cosmic-ray acceleration, the dynamics of ejecta-dominated SNRs, and the small-scale structure of SN ejecta. These observations will serve as a legacy of the Chandra mission and will provide invaluable data for future research on SNRs and cosmic rays.

Proposal Number: 04500278

Title: SUPERNOVA REMNANTS IN THE MAGELLANIC CLOUDS

PI Name: Frederick Seward

Chandra has now observed 20 of the brightest remnants in the Magellanic Clouds. Because the distances are known and the absorption low, this set is going to yield definitive data on remnant characteristics and evolution. We propose to observe 6 more remnants in the LMC. All are fainter and some are larger than those in the observed sample. We expect to see faint central sources and previously unobserved structure. These observations will span a region of parameter space not covered in the presently-observed sample aad will include some remnants with unique interesting features.

Proposal Number: 04500813

Title: FIRST MEASUREMENT OF THE GRAVITATIONAL REDSHIFT AT THE SURFACE OF A NEUTRON STAR

PI Name: George Pavlov

Chandra observations of 1E1207.4-5209, the neutron star (NS) in the PKS 1209-51/52 SNR, allowed us to discover absorption features in the NS thermal spectrum. This discovery provides a unique opportunity to measure the NS mass and radius and constrain the equation of state. We interpret the features as lines of once-ionized helium formed in the NS atmosphere with a magnetic field of 150 Teragauss, which implies a radius of 9-14 km for a one-solar-mass NS. To measure accurate line energies and resolve potentially multiple lines blended in the low-resolution CCD spectrum, we propose a deep observation with ACIS/LETG. This observation will provide a high-resolution phase-resolved spectrum, required for precise measurement of the NS mass and radius.

Proposal Number: 05500623

Title: The Cassiopeia A Explosion: Getting at the Core Issues

PI Name: Una Hwang

We propose a deep 1 Ms observation of the core-collapse remnant Cas A as a unique and important legacy of the Chandra Observatory. These data may be used to construct an observational nucleosynthesis curve giving composition by mass for all the X-ray emitting ejecta, and to study explosion asymmetries, turbulent mixing, particle acceleration, and the compact remnant. Particularly for a detailed study of the various processes that produce and distribute the heavy elements in a core-collapse explosion, Cas A is perhaps the best candidate target. Important results have been obtained with the existing <50 ks observations, but true breakthroughs may be expected with a much deeper exposure that allows us to study nucleosynthesis and core-collapse using Chandra's full spatial resolution.

Proposal Number: 05500645

Title: Spatially resolved grating spectrometry of the newborn supernova remnant SNR1987A

PI Name: Richard McCray

We propose to obtain spatially resolved spectra of the newborn supernova remnant SNR1987A with the ACIS-S/LETG on Chandra. The spectra will provide sufficient counts in several emission lines so that we can, for the first time, directly measure the velocity of the supernova blast wave through line profiles, and the electron temperature through line ratios, as functions of position. We will develop hydrodynamical models to interpret the dispersed X-ray spectra as well as complementary X-ray imaging data and UV and optical images and spectra from the HST and radio images from the Australia Telescope Compact Array.

Proposal Number: 06500333

Title: The Structure and Composition of Pulsar Winds and their Nebulae

PI Name: Patrick Slane

Chandra studies of pulsar wind nebulae have revealed stunning new information on the composition of the winds, the presence of jets and equatorial outflows, and the structure in and around the wind termination shock. Monitoring observations reveal temporal variations in resolved structures that challenge our understanding of particle acceleration and energy flow in these systems. Here we propose deep observations of G54.1+0.3 and PSR B1509-58 in order to probe the complex structure in their interior regions at arcsecond resolution. These observations will allow us to measure the spectrum and morphology of these features in order to constrain models for particle acceleration, the formation and structure of jets, and the geometry of particle flows in PWNe.

Proposal Number: 06500496

Title: Search for Sub-Millisecond Pulsars in 47 Tuc

PI Name: Robert Rutledge

We propose an observation with the ability to detect multiple isolated sub-millisecond pulsars among the unidentified X-ray sources in 47 Tuc, with significant secondary science. Observations in the X-ray band overcome the limited time resolution of even the best radio observations, allowing for the first time the setting of a new ``speed record'' for pulsars at sub-ms periods, below the now 20-year-old record of P = 1.558 ms. The detection of sub-ms pulsars would rule out equations of state for dense matter, provide even better clocks for their many physics applications, and create a strong impetus for future improvement of observational techniques. The absence of sub-ms pulsars would provide compelling evidence for a spin period limit.

Proposal Number: 06500950

Title: Spectra of Neutron Stars with Strongly Magnetized Hydrogen Atmospheres

PI Name: Marten van Kerkwijk

Neutron stars are unique laboratories for matter at extreme densities and magnetic field strengths. Much of the physics is encapsulated in neutron star spectra, but until recently no suitable sources were known. However, over the last year photospheric absorption features - likely due to hydrogen in strongly magnetized atmospheres - have been found for three nearby neutron stars. We propose to obtain high-quality, 300 ks LETG spectra of the two brightest sources. These data will allow examination of the absorption features and permit searches for other associated features. With detailed understandings of these lines one could measure the surface magnetic fields, compositions and temperatures, eventually leading to direct constraints on the equation of state at supra-nuclear densities.

Proposal Number: 07500318

Title: O-Rich SNR G292.0+1.8: A Textbook Example of a Galactic Core-Collapse SNR

PI Name: SANGWOOK PARK

G292.0+1.8 is the only Galactic supernova remnant (SNR) known to exhibit all the expected characteristics of a core-collapse SNR: stellar ejecta enriched in oxygen, an active pulsar and its wind nebula, and evidence for blast wave interaction with circumstellar material. G292.0+1.8 thus provides an invaluable opportunity for the study of nucleosynthesis and the shock evolution of core-collapse SNRs. We have commenced such a study with our initial Chandra observations of G292.0+1.8. In order to continue the study of this important object, we propose a Chandra Large Project (LP) of G292.0+1.8. The proposed observations will probe the structure of this SNR in unprecedented detail, and will provide an ideal complementary program to the existing Chandra Very Large Project of Cassiopeia A.

Proposal Number: 07500764

Title: Kepler's Supernova Remnant: Circumstellar Interactions, Particle Acceleration, and Type Ia Supernova Origins

PI Name: Stephen Reynolds

Recent work implies that Kepler's supernova remnant resulted from a Type Ia event, but circumstellar medium (CSM) interaction is also evident. Neither the progenitors nor the detailed explosion mechanisms of SNe Ia are understood, so Kepler offers us a unique opportunity to constrain the progenitor by studying CSM interactions, and the explosion mechanism by studying ejecta. We propose a 750 ks observation, to map the Fe K alpha line on spatial 5" scales, and obtain high-quality spectra in brighter regions on 8" scales. Fe K will map ejecta and discriminate thermal and nonthermal emission at rims. K lines of other alpha elements will show stratification; all should show Doppler broadening to characterize dynamics. A deep observation of Kepler should be a legacy of Chandra.

Proposal Number: 08500520

Title: SPATIALLY RESOLVED LETG SPECTROMETRY OF SNR1987A

PI Name: Richard McCray

We will obtain a spatially resolved LETG spectrum of the newborn supernova remnant SNR1987A. This observation will complement a 270 ks GTO observation of SNR1987A with the HETG. The proposed observations will provide spatial information to interpret the HETG observations and will measure the spectrum at wavelengths > 15 A where the HETG lacks sensitivity. With a projected source > 3 times brighter than it was during our Cycle 5 observation, we will be able to measure for the first time how the temperature distribution and kinematic velocity of the shocked gas has changed and how these parameters vary spatially around the ring-like source. The proposed observation is part of a large multi-wavelength campaign of observations with Spitzer, HST, and ground-based observatories.

Proposal Number: 08500758

Title: A Deep Chandra Observation of the Tycho Supernova Remnant

PI Name: John Hughes

We propose to obtain a very deep observation of the Tycho supernova remnant. Our observational goals include measuring the angular expansion of the forward shock and contact discontinuity, investigating the nature and origin of Fe-rich ejecta knots, and studying the spectral structure of the forward shock. For the expansion measurement we will compare to an existing Chandra observation taken in cycle 4 that was specifically optimized for subsequent expansion measurements. Tycho is the ideal remnant for studies of cosmic-ray modified dynamics and investigating key features of Type Ia supernova physics.

Proposal Number: 09500471

Title: A Deep Chandra Observation of G54.1+0.3

PI Name: Patrick Slane

Chandra observations of pulsar wind nebulae have revolutionized our understanding of these systems, revealing a wide variety of complex structures that all relate to the basic conversion of spin-down power to an axisymmetric wind with collimated outflows. Based on initial observations, G54.1+0.3 displays Doppler-brightened emission from the wind termination shock region, large-scale jets that form the elongated structure of the nebula, and faint emission that hints at a possible torus as well as large-scale filamentary structure. We propose a Chandra Large Project to obtain deep observations of G54.1+0.3 in order to resolve these structures, study their spectra, and derive properties related to flow conditions and the magnetic field structure of the nebula.

Proposal Number: 10500327

Title: An Extensive Study of the Youngest Galactic Supernova Remnant G1.9+0.3

PI Name: Stephen Reynolds

We have recently discovered that the smallest Galactic supernova remnant (SNR) in angular size, G1.9+0.3, is the youngest (known) Galactic SNR, with an age of about 100 years. The X-ray spectrum is lineless, well described by synchrotron emission with the highest rolloff frequency ever reported for a SNR. We propose a 500 ks Large Project observation of this unique object, which fills in a gap between SN 1987A (21 yr old) and Cas A (about 330). We wish to study detailed morphology, to compare with the 3 other Galactic synchrotron- dominated SNRs; spectra, to search for spatial variations and thermal emission; and variability, using this study for the first epoch. This object has enormous potential for the study of SNR hydrodynamics and strong-shock physics.

Proposal Number: 10500437

Title: The Spin and Magnetic Moment of the Neutron Star in Cassiopeia A

PI Name: Deepto Chakrabarty

How do the spin and magnetic moment of a neutron star relate to the properties of its massive progenitor and the supernova explosion? The best opportunity to study this question is the Cas A point source, the youngest known (300 yr) Galactic compact object. Its spectrum is unlike the classical Crab pulsar's, but is instead similar to both the more strongly magnetic "magnetars" and more weakly magnetic young pulsars. Much has been inferred about its progenitor and the supernova explosion from detailed studies of the supernova remnant. We propose to obtain a 500 ks HRC-S observation of the Cas A central point source, combining 350 ks of GO time and 150 ks of GTO time, in order to search for coherent pulsations down to the practical sensitivity limit of any current X-ray mission.

Proposal Number: 10500687

Title: A Deep Cycle 10 Chandra Observation of the Tycho Supernova Remnant

PI Name: John Hughes

We propose to obtain a very deep observation of the Tycho supernova remnant. Our observational goals include investigating the nature and origin of Fe-rich ejecta knots, and studying the spatial, spectral and temporal evolution of the nonthermal emission from the forward shock. Tycho is the ideal remnant for studies of cosmic-ray modified dynamics and for investigating key features of Type Ia supernova physics.

Proposal Number: 10500817

Title: The Unique Dynamical Vela Pulsar Wind Nebula

PI Name: George Pavlov

Chandra observations of the Vela pulsar-wind nebula (PWN) have revealed intriguing features in its structure and shown that the PWN brightness, shape, and spectrum change on a timescale as short as one week. Taking advantage of the known variability timescale, we propose a series of optimally sequenced observations to understand the PWN topology, dynamics, spectral structure, and interaction with the ambient matter.

Proposal Number: 10500824

Title: A Deep HETG Probe of the CSM Interaction in SN1996cr

PI Name: Franz Bauer

SN1996cr is one of the closest and X-ray brightest SNe detected on the sky. Like SN1987A, it appears to have exploded into a wind-blown bubble, sparking a unique temporal evolution wherein its X-ray flux has increased for >8 years now. Serendipitous HETG data allow us to identify several strong, broad, asymmetric emission-line complexes in SN1996cr, although their low-signal leaves much to interpretation. We propose a deep HETG observation of SN1996cr to resolve these emission lines and elucidate their nature (velocity structure, line diagnostics, abundances). It is imperative to observe SN1996cr while it remains bright, as it is the only SN beside SN1987A where such an observation is practical and in many ways is more representative of CSM-interacting core-collapse SNe.

Proposal Number: 11500272

Title: A Detailed Study of the Aged O-Rich Supernova Remnant 0049-73.6

PI Name: SANGWOOK PARK

O-rich supernova remnants (SNRs) provide an excellent opportunity for the study of core-collapse (CC) nucleosynthesis and the late-stage evolution of a massive star. While young O-rich SNRs (e.g., Cas A and G292.0+1.8) are being extensively studied, such studies are intrinsically limited because the early-stage of the blast wave and reverse shock may not reveal the full nature of metal-rich ejecta and the surroundings. Studies of relatively old O-rich SNRs are essential for a comprehensive understanding of CC SNRs, complementing those of young SNRs. The old O-rich SNR 0049-73.6 is a perfect example for such a study, revealing both high- and low-Z ejecta and well-evolved blast wave. Thus, we propose a deep 450 ks ACIS observation of 0049-73.6 for a detailed X-ray imaging spectroscopy.

Proposal Number: 11500276

Title: A Detailed Study of the Type Ia Supernova Remnant G299.2-2.9

PI Name: SANGWOOK PARK

Supernova remnant (SNR) G299.2-2.9 is a unique example of the Type Ia SNR which allows us a detailed 2-D spectral study for both of the metal-rich ejecta and ambient structures. Such studies of the ejecta and ambient medium are essential to reveal the detailed SNe Ia explosion mechanisms and their specific environments, which would critically impact their utility in cosmology. The proposed studies of both of the Type Ia SN ejecta and ambient structures cannot be performed with young historical Type Ia SNRs, and the mid-aged Type Ia SNR G299.2-2.9 provides a unique opportunity. Thus, we propose a 640 ks Chandra observation of G299.2-2.9. The proposed observation will serve a legacy which will be an essential basis for a high resolution spectroscopy of Type Ia SNRs with IXO and Astro-H.