Chandra X-Ray Observatory
	(CXC)

Joint Chandra/HST Accepted Cycle 3 Targets and Abstracts

Proposals from the following HST scientific categories were accepted by the HST TAC:


Click on the PI Name for the Proposal Abstract

PI NameTitleChandra timeTargets
Joel BregmanUltraluminous X-Ray Sources and Intermediate Mass Black Holes3 ksNGC4559
S. George DjorgovskiA Snapshot Survey of the Optically Selected Type-2 Quasars25 ksApproved for a maximum of five targets, and a maximum of 5 ksec per target, with the additional condition that Chandra observations will be scheduled and executed only for those targets for which HST observations have been obtained successfully, as part of the present snapshot program, before June 30, 2002.
Harald EbelingMeasuring the mass distribution in the most distant, very X-ray luminous galaxy cluster known32 ksCLJ1226.9+3332
Mike GladdersA New High-z Galaxy Cluster with Extraordinary Lensed Arcs From Multiple Sources15 ksRCS0224-0002
Gerard KrissSimultaneous HST, Chandra and FUSE Observations of Intrinsic Absorbers in AGN80 ksNGC7469
S. R. KulkarniGamma-ray burst progenitors: probing their environment55 ks 1 TOO
Karen LeighlyExploratory Observations of a New Bright Quasar20 ksPHL 1811
Raghvendra SahaiA YSO-like pulsed astrophysical jet and bipolar nebula in a dying star: WFPC2/STIS study of He2-9010 ksHe2-90
Meg UrryThe Physics of X-Ray/Optical Jets80 ks3C371.0 and PKS2201+044
William WelshFlares, Magnetic Reconnections and Accretion Disk Viscosity25 ksEM-CYG

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PI: Karen Leighly  
Proposal Title: Exploratory Observations of a New Bright Quasar
Approved Chandra Time (Ksecs): 20
Scientific Category: AGN/QUASARS                             

Abstract

  The VLA FIRST radio survey recently discovered a new, extremely bright
  quasar that is the second brightest optical object in the sky at z > 0.1.
  Optically classified as a Narrow-line Seyfert 1 galaxy (NLS1), PHL 1811 is
  not typical of this class of objects because it is a very weak X-ray
  source.  We propose short exploratory UV spectroscopic observations of
  this new bright quasar that will reveal its true nature and permit us to
  identify potential applications of future deeper observations.  PHL 1811
  may be the brightest luminous NLS1, in which case the study of the
  profiles and ratios of the emission lines will be valuable.
  Alternatively, PHL 1811 may be the brightest BALQSO, and the structure and
  composition of the BAL flow may be studied.  PHL 1811 may be a useful
  probe for local LyAlpha absorption and follow-up high resolution
  spectroscopy will be indicated; furthermore, the proposed  HST STIS
  observation will support the  FUSE observation scheduled for this fall.
  We also request short  Chandra observations to identify the origin of the
  faint X-ray emission.

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PI: Gerard Kriss
Proposal Title: Simultaneous HST, Chandra and FUSE Observations of Intrinsic
                Absorbers in AGN
Approved Chandra Time (Ksecs): 80
Scientific Category: AGN/QUASARS  
                          
Abstract

  Photoionized, warm absorbing gas is an important component of the nuclear
  structure of AGN. Approximately half of all low-z AGN show high-ionization
  UV absorption lines and X-ray warm absorbers, but the relationship of the
  UV-absorbing gas to the even higher ionization X-ray absorbing material is
  not yet understood. Only a handful of high-spectral-resolution
  observations with  HST,  Chandra or  FUSE currently exist (NGC 4151, NGC
  3516, NGC 3783, NGC 5548, Mrk 509). These show a diversity of kinematic
  structure and ionization states in the absorbers. We propose to increase
  significantly the sample of low-redshift AGN studied at high spectral
  resolution in the UV and the X-ray by obtaining simultaneous  HST,
  Chandra, and  FUSE spectra of NGC 7469 and Mrk 279. Both are bright AGN
  with   O vi absorption resolved in recent  FUSE observations. The new
  simultaneous observations will resolve the kinematics and ionization state
  of both the UV and X-ray absorbers. This will permit a definitive
  assessment of their relationship and give clues to their location in the
  nuclear region. Using the variety of ionization states and the multiple
  absorbing components, we will also reconstruct the ionizing spectrum.
  Understanding the absorbing gas and its influence on the radiation
  escaping from AGN has important implications for the radiative input to
  the IGM and the origins of the X-ray background.

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PI: S. George Djorgovski
Proposal Title: A Snapshot Survey of the Optically Selected Type-2
Quasars
Approved Chandra Time (Ksecs): 25
Scientific Category: AGN/QUASARS                            

Abstract

  We identified a population of emission-line objects in DPOSS, which can be
  plausibly interpreted as the long-sought type-2 quasars.  They have high-
  ionization Seyfert-2 like spectra, but with narrow-line luminosities
  comparable to those of the luminous type-1 quasars in the same redshift
  range. Keck spectropolarimetry confirms the presence of hidden QSO nuclei
  in them. This provides a major piece of evidence in favor of the unified
  schemes for AGN, and it should help extend our understanding of AGN in
  general.  This population may be a major contributor to the cosmic hard x-
  ray background. It is complementary to the optically dull hard x-ray
  sources found by Chandra. We propose to obtain multi-color images of a
  representative sample of these objects, in order to examine their
  morphology with the superior angular resolution of the HST.  We may be
  able to detect point-like nuclei which are not detectable in ground-based
  images, the dust lanes hiding them from our view, possible evidence for
  tidal interactions and the overall morphology of their hosts, etc.  We
  also propose for Chandra observations for a subsample of 5 objects, in
  order to probe the column densities of the obscuring material and to
  constrain their bolometric luminosities.  This study would greatly
  increase our understanding of these objects, which are an important
  missing link in the overall picture of AGN populations in the universe.

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PI: Meg Urry
Proposal Title: The Physics of X-Ray/Optical Jets
Approved Chandra Time (Ksecs): 80
Scientific Category: AGN/QUASARS                           

Abstract

  An important new probe of the physics of large-scale radio jets is
  possible with the discovery of resolved X-ray/optical jets. The optical
  emission comes from high energy electrons, which have short radiative
  lifetimes and so pinpoint particle acceleration sites. Spectral energy
  distributions of knots in two jets suggest the X-rays come from lower
  energy electrons inverse-Compton scattering the (beamed) cosmic microwave
  background.  This requires the jet to be still relativistic on kiloparsec
  scales (out to ~1 Mpc for the high-redshift jets!). This model robustly
  constrains both the bulk relativistic speed and the minimum electron
  energy in the jet, which together determine the total jet power.  To probe
  jet energetics and physics generally, and to test the ``Compton/CMB''
  interpretation specifically, we propose deep HST imaging of three X-
  ray/optical jets (PKS 1127--145, PKS 0637--752, 3C 371) and one optical
  jet (PKS 2201+044), plus Chandra observations of the latter two. The
  multiwavelength spectra of individual knots differ significantly, as does
  one jet from another, indicating the need for detailed high-resolution
  study of more than 1 or 2 jets. Along with the well-observed 3C 273 and M
  87 jets, the 4 proposed targets are the only known (or likely) nonthermal
  X-ray jets readily detected with Chandra and HST.

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PI: Harald Ebeling 
Proposal Title: Measuring the mass distribution in the most distant, very X-ray
                luminous galaxy cluster known
Approved Chandra Time (Ksecs): 32
Scientific Category: COSMOLOGY  
                           
Abstract

  We propose to obtain a mosaic of deep HST/WFPC2 images to conduct a weak
  lensing analysis of the mass distribution in the massive, distant galaxy
  cluster ClJ1226.9+3332, recently discovered by us. At z=0.888 this
  exceptional system is more X-ray luminous and more distant than both
  MS1054.4-0321 and ClJ0152.7-1357, the previous record holders, thus
  providing yet greater leverage for cosmological studies of cluster
  evolution.  ClJ1226.9+3332 differs markedly from all other currently known
  distant clusters in that it exhibits little substructure and may even host
  a cooling flow, suggesting that it could be the first cluster to be
  discovered at high redshift that is virialized. We propose joint HST and
  Chandra observations to investigate the dynamical state of this extreme
  object. This project will 1) take advantage of HST's superb resolution at
  optical wavelengths to accurately map the mass distribution within 1.9 h^-
  1_  50 Mpc via strong and weak gravitational lensing, and 2) use Chandra's
  unprecedented resolution in the X-ray waveband to obtain independent
  constraints on the gas and dark matter distribution in the cluster core,
  including the suspected cooling flow region.  As a bonus, the proposed
  WFPC2 observations will allow us to test the results by van Dokkum et al.\
  (1998, 1999) on the properties of cluster galaxies (specifically merger
  rate and morphologies) at z~ 0.8 from their HST study of MS1054.4-0321.

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PI: Mike Gladders
Proposal Title: A New High-z Galaxy Cluster with Extraordinary Lensed Arcs From
                Multiple Sources
Approved Chandra Time (Ksecs): 15
Scientific Category: COSMOLOGY                            

Abstract

  In the course of the Red-Sequence Cluster Survey (a 100 deg^2 optical
  imaging survey), we have discovered a stunning new example of strong
  lensing by a relatively high redshift (z~0.7) cluster. This lens system
  has more bright arcs, with better cluster azimuthal coverage than examples
  of lower z lenses previously imaged by HST (e.g., Abell 370, CL2244-0221),
  and is the only known lens at z>0.6 with such significant lensing.  At
  least 4 separate arcs are detected in our initial survey data, at 3-4
  different cluster-centric radii and hence likely corresponding to at least
  3 different background sources at 3 different redshifts. Moreover, these
  arcs are relatively bright (R_c~21.5-24.2) and hence redshifts should be
  readily obtainable using 8m class telescopes. The proposed HST WFPC2
  imaging, in conjunction with proposed VLT spectroscopy, offers an
  unprecedented opportunity to measure the core mass distribution of a
  cluster at such a high redshift. In combination with requested coordinated
  Chandra X-ray imaging, this will enable a direct comparison of the dark
  matter and baryonic components of the cluster, and enable a measure of
  cosmology via sources at different z. Furthermore, the arcs are bright
  enough to allow a detailed look at several high-z galaxies, via image
  reconstruction of the unlensed sources (only possible with HST images) and
  detailed spectroscopy.

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PI: Joel Bregman 
Proposal Title: Ultraluminous X-Ray Sources and Intermediate Mass
Black Holes
Approved Chandra Time (Ksecs): 3
Scientific Category: GALAXIES & CLUSTERS                             

Abstract

  Ultraluminous X-ray sources (ULX) are second only to AGNs in point-source
  luminosity yet they have no known optical counterparts.  These
  extraordinary X-ray objects, which radiate at the Eddington luminosity of
  a 30-100 M _\odot  object, are non-nuclear sources in normal disk
  galaxies. \ One explanation is that they are binary systems where the
  accreting black hole has a mass of 30-100 M_\odot , although this
  challenges stellar evolutionary models, which do not predict remnants
  larger than about 10 M _\odot . Another possibility is that ULXs are
  intermediate mass black holes (10^3-10^4 M_\odot ), acting as micro-
  quasars in galaxy disks and representing the link between stellar black
  holes (4-10 M_\odot  ) and supermassive black holes (10^6-10^10 M_\odot ).
  We can distinguish between the models by identifying the optical
  counterparts of ULXs and measuring their colors. \ This would be a
  fundamental step in gaining an understanding of these enigmatic and
  possibly new astronomical objects.

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PI: S. R. Kulkarni
Proposal Title: Gamma-ray burst progenitors: probing their environment
Approved Chandra Time (Ksecs): 55
Scientific Category: GALAXIES & CLUSTERS                             

Abstract

  Gamma-ray burst astronomy is a field maturing at a phenomenal rate. Only
  three years after the discovery of fading long-wavelength counterparts, we
  now have distance measurements for dozens of events, we have developed a
  detailed theoretical framework for understanding the X-ray -- radio
  afterglow lightcurves, and observational evidence now ties the progenitors
  of long GRBs (those studied to-date) to the collapse of massive stars.
  While progress has been rapid, three important new observational and
  theoretical discoveries, formulated over the last twelve months, allow us
  to address new and in many cases more sophisticated questions than could
  have been posed a year ago. These developments: the discovery of X-ray
  lines in GRB 991216; the observation that N_H as deduced from X-ray
  afterglow are one to two orders of magnitude larger than the dust
  extinction inferred from optical afterglow; and the growing realization
  that the afterglow emission may exhibit features of dust echoes, appear to
  offer unexpected and new diagnostics that will directly inform us about
  the progenitor, the circum-progenitor material and the immediate
  interstellar environs.  These motivate us to propose an aggressive program
  for cycle 10. As one of the most actively evolving areas in astronomy
  today, we anticipate the contributions of HST to be part of the
  foundations of this new and important field.

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PI: William Welsh  
Proposal Title: Flares, Magnetic Reconnections and Accretion Disk
Viscosity
Approved Chandra Time (Ksecs): 25
Scientific Category: HOT STARS                               

Abstract

  Accretion disks are invoked to explain a host of astrophysical phenomena,
  from protostellar objects to AGN. And yet the mechanism allowing accretion
  disks to operate are completely unknown. This proposal seeks to observe
  the ``smoking gun'' signature of magnetically--driven viscosity in
  accretion disks. Magnetically--induced viscosity is a plausible and
  generally accepted hypothesis (for esthetic reasons), but it is completely
  untested. Determining the cause of accretion disk viscosity is of major
  significance to all accretion--disk powered systems (e.g. CVs, X--ray
  binaries, AGN and protostellar disks). These data will also firmly
  establish the importance of magnetic fields in accretion disks. Because of
  its known flaring properites, we will observe the accretion disk in EM Cyg
  simulataneously with STIS/FUV and CHANDRA. The simultaneous X-rays are
  absolutely necessary for the unambiguous detection of accretion disk
  magnetic reconnection flares.

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PI: Raghvendra Sahai 
Proposal Title: A YSO-like pulsed astrophysical jet and bipolar nebula in a
       dying star: WFPC2/STIS study of He2-90
Approved Chandra Time (Ksecs): 10
Scientific Category: ISM AND CIRCUMSTELLAR MATTER 

Abstract

  We have discovered an extended, highly-collimated, bipolar jet in He2-90,
  an object long classified as a planetary nebula (PN). The discovery images
  (obtained with WFPC2/HST) show that the morphology of He2-90 does not look
  like that of any known PN, but resembles that of a classical young stellar
  object (YSO). This appears to be a unique object.  We will determine the
  speed of the jet (only slightly inclined to the sky plane) through proper
  motion observations of the knots in the jet: a 2nd-epoch WFPC2 H-alphapha
  image will be obtained for comparison with the Sep99 discovery image. It
  is crucial to observe the velocity field of the flow at the highest
  spatial-resolution, as close as possible to the origin of the jet in order
  to constrain theories for how the jet is driven, and the nature of the
  central object. We propose to do this by mapping the jet near the central
  source using the long-slit, medium resolution mode of STIS. We also
  propose supplemental observations: low resolution STIS spectra for
  obtaining nebular diagnostics, coupled with narrow-band imaging with WFPC2
  in emission lines such as NII, OI and OIII and continuum filters for
  mapping excitation variations in the nebula and jet and the extinction in
  the central dense dusty disk region. Coordinated Chandra X-ray
  observations (with ACIS-I) will be made to check the association of an
  EGRET >~mma-ray source which lies in the direction of He2-90.

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Last modified: 12/02/10

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