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Proposal Number: 09500023

Title: Investigating possible magnetar-like outburst behaviour from high-B radio pulsars and XDINSs

PI Name: Mariano Mendez

We propose a Chandra ACIS-S ToO observation of 10ks of any X-ray Dim Isolated Neutron Star (XDINS) and high magnetic field radio pulsar within 30 days from the detection of an increase (of an order of magnitude) of their soft X-ray, optical or radio flux. Radio and X-ray outbursts have been recently discovered from magnetars. This study is aimed at unveiling similarities between the high-B pulsar and XDINS classes with respect to the magnetar class, and consequently to understand their differences despite the common high magnetic fields (greater than the electron critical magnetic field). Through this Chandra observation we will study any timing and spectral variabilities connected with these outbursts.

Proposal Number: 09500026

Title: Galactic Supernova Remnant G272.2-3.2

PI Name: Gordon Garmire

We propose to observe Galactic supernova remnant (SNR) G272.2-3.2. G272.2-3.2 is one of the SNRs discovered in X-rays, and has been suggested to a thermal composite SNR. However, the previous studies indicated that the properties of this SNR is extremely uncertain. The proposed Chandra observation will be useful to resolve many aspects of the uncertain nature of G272.2-3.2, including the origin of the SNR.

Proposal Number: 09500030

Title: Snap-shot survey of potential GeV and TeV pulsars

PI Name: Gordon Garmire

We propose to observe a number of energetic, young, radio pulsars that has not yet been studied in X-rays. The pulsars and their wind nebulae are especially interesting since they are expected to be the GeV and TeV sources detectable in the near future with the Glast and HESS observatories. In the short, 10 ks, exposures we expect to detect emission from the pulsars and PWNe in all cases. Obtained images and spectra will allow us to select the brightest, most interesting objects for more detailed follow-up studies.

Proposal Number: 09500037

Title: High Resolution HRC Imaging of Supernova Remnant 1987A

PI Name: Stephen Murray

ACIS observations of SN 1987A have provided unique images of an evolving young supernova remnant. However, because the ACIS pixels undersample the PSF, these data cannot be used to derive robust measurements and uncertainties for parameters such as the radius and thickness of the emitting shell, nor can they quantitatively differentiate between geometries such as a thick shell or a tilted ring. We consequently propose an HRC observation of SN 1987A. When combined with ACIS and radio data from nearby epochs, the HRC data will allow a high fidelity reconstruction of the underlying morphology. Note that these HRC data complement rather than conflict with any Cycle 9 ACIS observation of SN 1987A, since ACIS data carry spectral information, while HRC data have superior spatial resolution.

Proposal Number: 09500130

Title: The extreme late-time light curve of GRB 060729

PI Name: Dirk Grupe

Conflicting results from optical measurements on one hand and recent Swift X-ray observations on the other challenging the predictions from the standard 'fireball' model of Gamma-Ray Bursts (GRBs) that jet openning angles can be determined from the light curve's break times: While optical light curves suggest early break times and therefore small opening angles, the Swift XRT observations show no jet breaks in the majority of afterglow light curves, even weeks after the trigger. Here we propose to observe the bright X-ray afterglow of GRB 060729 twice with Chandra for 80 ks at the beginning and 120 ks at the end of the AO-9 to extend its light curve beyond any X-ray afterglow that has ever been observed, putting strong constrains on the opening angle and GRB theory.

Proposal Number: 09500172

Title: The 'black-widow' pulsar in X-rays

PI Name: Vyacheslav Zavlin

We propose a deep observation of the "black-widow" eclipsing millisecond pulsar B1957+20 in a 33-ks orbital period binary system with a low-mass companion. The system is the only currently known example where the interactions of the pulsar wind with the interstellar medium and the wind from the companion have been observed. This was accomplished by a previous Chandra observation that lasted 43 ksec. These interactions are tools for elucidating properties of the relativistic wind which carries away the pulsar's rotational energy. Our study will provide much more detail for the physical properties of both the termination and intrabinary shocks and, hence, further insight into the nature of pulsar winds.

Proposal Number: 09500216

Title: Chandra Observations of Young, Energetic Supernovae

PI Name: David Pooley

In the entire history of X-ray astronomy, only about three dozen core-collapse supernovae (SNe) have been detected at ages of days to years old. Of these, only a handful have been well-followed temporally. Few general trends have emerged, and there is a clear need for better X-ray coverage at ages of ~years. Two SN subclasses stand out as deserving of particular attention, namely, the type Ib/c SNe, which have been associated with long-duration gamma-ray bursts, and the type IIn SNe, which are very poorly understood but have the highest X-ray luminosities seen in SNe. We propose observations of a number of interesting SNe of these subclasses at ages of years.

Proposal Number: 09500239

Title: A Deep Chandra Observation of SMC SNR 0104-72.3

PI Name: Sangwook Park

We propose to observe the supernova remnant (SNR) 0104-72.3 in the Small Magellanic Cloud (SMC). SNR 0104-72.3 is relatively faint and the X-ray images show ~arcsec scale substructure. There is also an X-ray point source within the SNR boundary. Furthermore, the origin of 0104-72.3 has been controversial between Type Ia and II. X-ray characteristics of 0104-72.3 make a deep Chandra ACIS observation the unique tool for the study of this SNR. Our proposed 120 ks ACIS observation would be useful to reveal the origin of 0104-72.3.

Proposal Number: 09500297

Title: Timing PSR J1852+004 in Supernova Remnant Kes 79: Plan B

PI Name: Jules Halpern

Timing of PSR J1852+0040 in SNR Kes 79 has shown no change in its spin period. Its surface B is < 2x10^11 G in the dipole spin-down formalism, unique for a young, rotation-powered pulsar, and incompatible with its X-ray luminosity and pulse properties. Instead, it may be accreting supernova debris, in which case it can remain in a near-equilibrium spin with only random torque noise. We propose to continue our timing of PSR J1852+0040 to measure its P-dot and/or torque noise in order to decide between these models. In any model, PSR J1852+0040 must have a weak magnetic field, which may also explain the class of CCOs, e.g., 1E 1207.4-5209. In those pulsars born spinning slowly, the dynamo may generate a weaker field, which enables it to accrete.

Proposal Number: 09500337

Title: Chandra Observations of New X-ray Supernovae

PI Name: David Pooley

We propose to continue our X-ray studies of Type II and Type Ib/c supernovae (SNe). The Swift satellite has ushered in a new era of studying SNe in the X-rays, obtaining densely sampled X-ray lightcurves for the first time. However, its spatial resolution is often not good enough to separate a SN from nearby sources. We propose short Chandra observations to alleviate this. These observations will assess the X-ray environment of newly discovered Swift SNe to determine any possible source confusion or contamination of the SN flux. Our strategy makes the best use of the capabilities of each observatory.

Proposal Number: 09500381

Title: Phase-resolved Imaging of Compact Structures in a Pulsar Bow Shock

PI Name: Chi-Yung Ng

G359.23-0.82 ("the Mouse") is the ideal system for studying the physics of pulsar bow shock nebulae. However, ACIS observations of the Mouse offer little insight into compact nebular structures close to the pulsar, because of both pile-up and the likely presence of significant X-ray emission from the pulsar itself. We here propose an HRC-I observation of the Mouse, phase-resolved imaging from which will provide high-fidelity data on nebular structures close to the pulsar. With these data, we can identify possible wisps, jets, knots or other structures near or within the Mouse's termination shock, allowing us to compare the properties of the relativistic flow and particle acceleration process under a bow shock geometry to those seen in the well-studied "Crab-like" nebulae.

Proposal Number: 09500446

Title: A Measurement of the Expansion Rate of SN 1006

PI Name: Robert Petre

We propose to make the first X-ray proper motion measurement of SN 1006, by taking an identical 70ks ACIS-S exposure of the bright NE rim to one taken 7 years ago. If X-ray expansion is comparable to radio, then the shock proper motion of 3000 km/s produces a shift of 7 ACIS pixels compared with the reference observation. Proper motion of thin (10 arcsec) nonthermal filaments and interior ejecta knots will be easily detected, as will brightness changes at the 10 percent level on 3-5 arcsec scales. Brightness changes in the nonthermal rims would arise from the influence of spatial variations in magnetic field strength on synchrotron loss timescales. SN 1006 is the best remnant in which to measure the proper motion of nonthermal shocks because it is nearby, bright, and has fast shocks.

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: 09500479

Title: The X-ray Afterglow of a Gamma-ray Burst detected and localized with the AGILE gamma- and X-ray detectors

PI Name: Marco Feroci

AGILE will be the first mission to observe GRBs in the range ≥ 30 MeV after the afterglow revolution, allowing the high energy emission to be studied for the first time in the frame of information derived from the afterglow, such as distance, host, decay law, .. We propose a 60 ks ToO observation of one AGILE GRB, observed in gamma-rays and arcmin localized at X-rays by SuperAGILE. The main scientific objectives are the arcsec localization of the X-ray counterpart, allowing for the first time ever an association of a gamma-ray emitting GRB with counterparts at other wavelengths (thus possibly with a redshift and a host galaxy), and the study of the X-ray afterglow, correlated to the observable prompt and/or delayed emission in the 30 MeV 50 GeV range.

Proposal Number: 09500556

Title: Determining the nature of the quasi-pointlike TeV source HESS J1858+020

PI Name: R gis Terrier

Most HESS sources are very extended objects for which counterparts are difficult to find. But all point like or quasi point like objects have rich X-ray counterparts. In particular, HESS J1813-178 has revealed a bright X-ray nebula enclosed in a radio shell. Recent Chandra observations have resolved a very energetic pulsar candidate in this nebula. We propose to observe the newly discovered quasi point like source HESS J1858+020, which is devoid of any X-ray observations. Its TeV spectral characteristics are very similar to those of HESS J1813-178, reminding a possible young pulsar wind nebula. We propose to test this hypothesis using a 30 ks ACIS-I pointing which should be able to reveal a pulsar wind nebula or on the contrary a possible compact source origin of the emission.

Proposal Number: 09500565

Title: Investigating the X-ray Variability of Cassiopeia A

PI Name: Daniel Patnaude

We propose a 50 ksec ACIS-S observation of Cas A to follow X-ray flux changes associated with ejecta recently encountered by the reverse shock. This will allow us to investigate Cas A's near-term X-ray evolution and the fine-scale structure of its SN debris. We also request the Chandra observation be followed by HST NICMOS & WFPC2 images of four identified X-ray variable features in the high ionization NIR lines of [Si VI] and [Si X] and low ionization optical lines of [S II] and [O III]. The proposed X-ray/optical/NIR observations will yield a multi-wavelength study of the remnant's advancing reverse shock in an inhomogeneous multi-phase ejecta medium at resolutions down to a fraction of an arcsecond, providing a hi-resolution broad temperature study of reverse shock heated SN ejecta.

Proposal Number: 09500572

Title: Completing a Small Chandra Survey of Hard X-ray Sources in Gamma-Ray Error Boxes

PI Name: Mallory Roberts

Recent X-ray and radio studies of unidentified high-energy gamma-ray source error boxes (detected by EGRET) have yielded numerous likely counterparts. These have been young pulsars coincident with steady EGRET sources, rapidly moving pulsar wind nebulae coincident with variable EGRET sources, radio emitting Be X-ray binaries, background blazars, and associations of massive stars. We propose brief observations of the final 3 hard X-ray sources discovered in an ASCA survey of Galactic GeV source error boxes to determine if any are members of the above source classes or can be identified with other potential gamma-ray emitters. The precise positions from these observations may be important for successful blind searches for pulsations in data from GLAST.

Proposal Number: 09500577

Title: A Search for X-ray Pulsations from Rotation-Powered Millisecond Pulsars

PI Name: Kent Wood

We propose HRC-S observations of 8 rotation-powered millisecond pulsars (RMSPs) to search for pulsations and measure fluxes. We show it is not possible to identify a single figure of merit that explains current detection patterns and prioritizes new searches. A blend of two figures of merit (successful with X-ray hard and thermal subclasses respectively) maximizes prospects for new detections. This survey will clarify the roles of X-ray and gamma-ray emission from RMSPs, and prepares for GeV observations with GLAST. The number of known X-ray RMSPs of the hard subclass could be doubled. Enlarging source counts is essential to understanding the characteristics of RMSPs seen in radio, X-rays, and gamma-rays.

Proposal Number: 09500603

Title: Shock Interactions in the Supernova Remnant IC443

PI Name: Una Hwang

We propose two ACIS-I observations to obtain high-quality spectra and images of the bright northeast region of the supernova IC 443. We aim to identify coherent shock structures in conjunction with optical images, and to perform spatially resolved spectroscopy and spectral imaging. The northeast region of IC 443 is interacting with diffuse interstellar medium, atomic and molecular clouds at its various boundaries. We will explore compare the X-ray ane optical morphologies in detail, and measure the temperature and density structures of the X-ray emitting gas behind these different shock environments. We will also search for correlations with coronal [Fe X] and [Fe XIV] emission to look for signatures of cloud evaporation.

Proposal Number: 09500615

Title: The Peculiar X-Ray Evolution of Supernovae 1978K, 1979C and 1993J

PI Name: Stefan Immler

Supernovae (SNe) 1978K, 1979C, and 1993J are some of the brightest and best observed SNe in the X-ray regime. Over the past ~2 decades, SNe 1978K and 1979C have shown no evolution in X-rays, with high sustained (0.2-10 keV) luminosities around E39 ergs/s and high inferred mass-loss rates of the progenitors (>E-4 M_sun/year) over the last 40,000 years prior to their explosions. However, the latest Chandra, XMM-Newton and Swift observations show a dramatic decrease in their X-ray luminosities similar to that of SN 1993J. We propose Chandra observations to follow their fast rates of decline which will bring the long-term X-ray monitoring of these three SNe to a final closure.

Proposal Number: 09500627

Title: ToO Observations of Soft Gamma Repeaters

PI Name: Peter Woods

Soft Gamma Repeaters are rare sources of transient burst emission, probably magnetars (i.e. strongly magnetized neutron stars). Each of the SGRs has a persistent X-ray counterpart and some show coherent pulsations. During burst active phases, these counterparts undergo changes in their energy spectrum and pulse properties. Measuring the effects of burst activity are diagnostic of the burst mechanism and SGRs in general. In the event of detection of substantial burst activity from an SGR, we propose to make Chandra ToO observations of any of the four known sources, SGR 1900+14, SGR 1806-20, SGR 1627-41, SGR 0526-66, the SGR candidate SGR 1801-23, as well as any newly discovered SGR source.

Proposal Number: 09500628

Title: Measuring the Expansion Rate of G266.2-1.2

PI Name: Glenn Allen

We propose to reobserve the bright northwestern rim of G266.2-1.2 five years after our first observation of this region. The goal of the new observation is to measure the expansion rate of the remnant and constrain its age. The age of the remnant is controversial. Some report evidence of line emission associated with the decay to titanium-44, which implies that the remnant must be young (< 1200 yr). Others find no such evidence and argue that the absorption column density favors a large distance (and older) remnant. If the expansion over the last four years < 6.0", then the remnant is too old (> 1200 yr) to have a significant amount of titanium-44 left. If the expansion is much larger, then the results indicate the remnant is young enough to contain a substantial amount of titanium-44.

Proposal Number: 09500752

Title: X-ray Observations of 11 Millisecond Pulsars in M28

PI Name: Jonathan Grindlay

We propose a deep X-ray survey of the globular cluster M28 which will yield a wealth of important and unique science, ranging from the first direct measurement of the magnetic field of a millisecond pulsar and constraints on the neutron star equation of state to likely X-ray/optical (HST) detection of a re-exchanged binary MSP. The proposed joint HST WFPC2 observation will tie the X-ray, optical, and radio data to a common astrometric frame allowing an unambiguous identification of numerous cataclysmic variables and active binaries in M28 as well as making possible the first direct optical detection of a millisecond pulsar.

Proposal Number: 09500789

Title: Constraining GRB physics through their afterglow light curves

PI Name: Evert Rol

Our current understanding of gamma-ray burst afterglow light curves has become increasingly confused, and the validity of the standard synchrotron fireball model for GRBs is nowadays increasingly questioned. In particular, achromatic breaks due to the lateral expansion of the GRB jet are not substantiated by Swift X-ray observations. It is only through this that the true energies of GRBs are constrained, and that questions such as the true rate of GRBs and the determination of cosmological parameters can be answered. We propose to use CXO to construct the late time X-ray light curves for several Swift bursts. These observations will search for evidence of achromatic jet breaks, providing the necessary insight into the GRB evolution, and the energy and activity of the central engine.

Proposal Number: 09500791

Title: A Chandra observation of the proper motion of RCW 89

PI Name: Yoichi Yatsu

In cycle 6 we observed RCW 89 to resolve fine structure in X-ray band. From the observation we discovered that the X-ray emitting region in RCW 89 are moving away from the pulsar at a velocity of 5000 km/s. The motion of X-ray emitting region may represent the propagation of the shock front driven by the supernova blastwave or the relativistic pulsar jet. And these results can be an evidence for that PSR B 1509-58 and MSH 15-52 (RCW 89) are physically linked. However the calculated velocity has large uncertainty caused by the low quality of the image taken by the first observation of PSR B1509-58 on 2000, in which RCW 89 was on the edge of ACIS-I with worse photon statistics. We therefor propose another 60 ks Chandra observation of RCW 89.

Proposal Number: 09500804

Title: HESS J1731-347: The first TeV pulsar wind nebula from a supersonic pulsar with an X-ray bow shock geometry?

PI Name: Gerd Puehlhofer

We propose to observe the X-ray counterpart to the TeV source HESS J1731-347 in imaging mode with Chandra. Based on our Suzaku observations of the TeV source, we believe that the object can be identified as a pulsar wind nebula driven by a pulsar with supersonic motion. Arcsecond X-ray imaging should reveal the geometry of this object, similar to what is observed with Chandra for the few other examples of this small but interesting class of X-ray pulsar wind nebulae.

Proposal Number: 09500845

Title: Constraining the Continued Rise of SN1996cr

PI Name: Franz Bauer

Recently confirmed SN 1996cr ranks among the closest and X-ray brightest supernovae (SNe) detected on the sky. Past X-ray observations of 1996cr have shown it to have a unique spectral evolution compared to typical type-II SNe, wherein the X-ray flux is still increasing 10 years post-explosion (akin to 1987A). This rising emission is attributed to the ejecta propagating through increasingly dense circumstellar material (e.g., wind) leftover from the past evolution of the supergiant progenitor. We propose an ACIS-S observation of 1996cr to monitor the evolving X-ray spectrum of this unique object and trace back its evolutionary history.

Proposal Number: 09500854

Title: Study of a New Class of Isolated Neutron Star -- 1RXS J141256.0+792204

PI Name: DEREK FOX

We have discovered a new candidate isolated neutron star (INS), the first F_X/F_opt>5000 object to be discovered in seven years, and quite probably the first NS of any sort to be identified in the Galactic halo. Treating the source as analogous to the 7 known INSs implies that, at a height of 4.8 kpc above the Galactic plane, it must have either a very high spatial velocity (> 4800 km/s) or a cooling time much longer than NS cooling theories predict (> 24 Myr). Alternative interpretations of the source as a magnetar or `compact central object' suffer from their own difficulties. We therefore propose to make the first detailed X-ray characterization of this INS, with Chandra observations providing a high S/N CCD-spectrum, investigating long-term variability, and searching for pulsations.

Proposal Number: 09500890

Title: AO9 Chandra Monitoring of SNR 1987A

PI Name: David Burrows

SNR1987A provides a unique opportunity to study the development of a young supernova remnant at high resolution. We have monitored SN/SNR1987A at roughly six month intervals since October 1999. The remnant is expanding and is increasing exponentially in X-ray brightness. We propose to continue this monitoring program with two additional observations in AO9, spaced six months apart. We will perform spatially-resolved spectroscopy in addition to monitoring the expansion and the development of new X-ray hot spots. We do not consider this proposal to conflict with the proposed HRC observations, since our science requires the energy resolution of the ACIS.

Proposal Number: 09500896

Title: TINY HICCUPS TO TITANIC EXPLOSIONS: Tackling Transients in Anomalous X-ray Pulsars

PI Name: Victoria Kaspi

Recently discovered transient events in Anomalous X-ray Pulsars (AXPs) may be a Rosetta Stone for understanding the persistent emission from magnetars. They also may hold the key to quantifying the number of magnetars in the Galaxy. Here we request Chandra TOO time to observe any AXP following a rare transient event, including a major outburst or a long-duration flare. Specifically, the requested observations will determine the pulsed fraction and spectral evolution of a transient AXP event as the source relaxes back to quiescence, in order to quantitatively test the "twisted magnetosphere" model for magnetars, and establish the basic phenomenology of transient AXP events.

Proposal Number: 09500898

Title: PSRJ1832+0029: a unique probe of pulsar emission physics

PI Name: Duncan Lorimer

We have discovered very unusual behavior in PSR J1832+0029, a 533-ms radio pulsar which switches between on and off states on timescales of several hundred days. Remarkably, the pulsar's spin-down rate almost doubles when the radio emission is on. This is even more dramatic than observed for PSR B1931+24 for which no satisfactory theory presently exists. Unlike PSR B1931+24, J1832+0029 is nearby (1.3 kpc) and an excellent target for X-ray detection. Here we request a 20 ks ACIS observation to study the X-ray emission of PSR J1832+0029 in its on or off state. With a second exposure requested by a companion TOO proposal, the observations would distinguish between radio emission quenching mechanisms that are either intrinsic to the pulsar or caused by accretion from an orbiting companion.

Proposal Number: 09500899

Title: PSRJ1832+0029: a unique target for pulsar emission physics

PI Name: Duncan Lorimer

We have discovered very unusual behavior in PSR J1832+0029, a 533-ms radio pulsar which switches between on and off states on timescales of several hundred days. Remarkably, the pulsar's spin-down rate almost doubles when the radio emission is on. This is even more dramatic than observed for PSR B1931+24 for which no satisfactory theory presently exists. Unlike PSR B1931+24, J1832+0029 is nearby (1.3 kpc) and an excellent target for X-ray detection. Here we request a 20 ks ACIS TOO to study the X-ray emission of PSR J1832+0029 in its on or off state, triggered by radio monitoring following a companion GO proposal. The observations would distinguish between radio emission quenching mechanisms that are either intrinsic to the pulsar or caused by accretion from an orbiting companion.

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