ArgosX: Advances in WideAngle Xray Instrumentation

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Argos-X Advances in Wide-AngleX-ray
Instrumentation

• Ron Remillard (MIT) Argos-X Science Team

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Status

• Status SMEX 2008 proposal
• top-level science grade, but not selected
• Argos-X Team
• A. Levine, E. Morgan, D. Chakrabarty, J. Homan
  (MIT),
• P. Ray, B. Phlips, K. Wood, E. Novikova (NRL),
• G. De Geronimo (Brookhaven), F. Marshall
  (NASA/GSFC),
• J. Bloom, E. Quataert (UC Berkeley), S.
  Eikenberry (U FL),
• M. Elvis (Smithsonian CFA), H. Krawczynski
  (Washington U),
• J. Miller (U MI), J. Orosz (SDSU),
• F. Aharonian (MPIK Heidelberg GER),
• R. Fender, I. McHardy (U Southampton UK),
• V. Kaspi (McGill CA).

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Outline

• Measurement Objectives for advancement
• Camera Performance with Si pixel detectors
• Design Options as a SMEX or on AXTAR
• Science Objectives for a wide-angle Instrument

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An Advanced Wide-Angle Monitor (concept)

• Measurement Objectives
• View a large solid angle (half sky)
• Gain very long exposure time (108 s)
• Data products like pointed instrument
• (e.g., 1.5 - 30 keV _at_ 0.6 keV resolution
• 128-channel spectra 100 ms timing
• standard products event archive)

Observe moments of critical interest (e.g.,
impulsive jet ejections state transitions
fast novae bursts superbursts other cosmic
explosions tidal disruptions into SMBH SNe
breakout orphan GRBs)
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SMEX concept / 25-Camera Option
Si detectors (2.5 mm pixels) available from NRL
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SMEX concept / 25-Camera Option
Live Sky Coverage
Fields of View
Primary obstacle 42 Crab of diffuse X-ray
background, all-sky
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Design Options for an Instrument

• Working Assumptions
• Camera directions based on 32-vector figure
  (dodecahedron with 12 faces 20 vertices),?
  camera FOVs of 40o x 40o then cover the sky,
• Stationary pointing, with a defined solar axis,
  maintained by simple slews of 1o per day,
• Satellite in Equatorial, low-Earth orbit (no
  SAA Earth shadow is one-third of sky).

Num. cameras S/C Active sky coverage 31
SMEX 65 25 SMEX 50 12
AXTAR? 30
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An Advanced Wide-Angle Monitor

• Science Objectives
• Physical properties of black holes, neutron
  stars, supermassive BHs
• Accretion physics problemsinvolving general
  relativity
• Observe moments of critical interest
• X-ray based GRB survey
• Science Synergy
• Transient Monitor for Other Programs
• Partner for wide-angle radio and optical
  observatories
• Eyes for Advanced LIGO

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X-ray Transients Timeline for Science Opportunity
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3 States of Active Accretion
GRO J1655-40 (1996) Energy spectra
Power density Spectra spectra
State physical picture ?
steep power law Disk ?? ? thermal
? hard state

Energy (keV)
Frequency (Hz)
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Data Quality

• Argos-X simulated spectra from a BH binary (Jon
  Miller RR)
• 0.5 Crab source for 4 ks and 0.1 Crab in 1 day.

Continue efforts to infer BH spin from thermal
continuum and broad Fe line
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Accreting NS Subclasses
Atoll sources (common bursters) and Z-sources
(near- or super-Eddington) atoll
transient bright atoll source Z source
extreme island, island, banana branch
horizontal, normal, and and banana branches
(upper and lower) flaring
branches
Top to bottom
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Energy Spectra Power Spectra of Accreting NS
Progress in detailed models for Z sources See
Lin, Remillard, Homan (astro-ph 2009) and
Church et al. (astro-ph 2008)
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Science Objectives for Argos-X

• Timing Themes for X-ray Binaries
• Periodicities (orbital NS spin spin
  evolution)
• Low-frequency QPOs in accreting BHs and NSs
• kHz QPO studies of Sco X-1

Sco X-1 with Argos-X in 10 ks
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Science Objectives for Argos-X

• Science Questions for Supermassive Black Holes
• Long term power-density spectra of bright AGNs
  ( 1 mCrab)
• Outburst properties of Blazars
• Finding obscured AGN in the local universe
  (5-30 keV)
• Tidal disruption events (stellar infall) into
  non-active SMBH

Simulation for Argos-X By J. Bloom and E. Quataert
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Conclusions

• New Technology (pixellated Si low-power ASICS)
  can greatly advance the effectiveness of
  wide-angle X-ray cameras,
• Continuous coverage at 1.5-30 keV with good
  spectral resolution can be used to measure
  physical properties of compact objects and to
  better investigate accretion in strong gravity,
• Increases in live sky coverage would provide
  unique observations of explosive events at
  critical times of interest,
• The dimensionality of accretion physics questions
  (i.e., object type X subclass x
  state/branch X luminosity level)inevitably
  requires high exposure times and many targets.

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SMEX / 25 Camera Option
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BH States Overview
4U 1630-47 Mx unknown (ISM dust) Outburst
every 2 yr More than 50 INT (se also Tomsick
et al. 2005) Thermal x Hard (jet) g Steep
Power Law D Intermediate O
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Empirical State Definitions Key Parameters

Thermal SPL Hard disk fraction
fdisk 75 none 0.05 rms 0.01
power-law photon index 2.4
1.4 -- 2.1 rms power (0.1-10 Hz) 0.075 0.10 __________ gap
conditions intermediate
Physical models kerbb fit BH spin (a)
?? multi-n jet models
ADAF models

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3 States of Active Accretion
XTE J1550-564 (1998) Energy spectra
Power density spectra
State physical picture ?
steep power law Disk ?? ? thermal
? hard state

Energy (keV)
Frequency (Hz)