Extreme Physics Explorer: A Mission to Test Basic Physics Martin Elvis Harvard-S

Extreme Physics Explorer: A Mission to Test Basic Physics Martin Elvis Harvard-S www.phwiki.com

Extreme Physics Explorer: A Mission to Test Basic Physics Martin Elvis Harvard-S

Green, Judy, Freelance Children’s Book Writer has reference to this Academic Journal, PHwiki organized this Journal Extreme Physics Explorer: A Mission to Test Basic Physics Martin Elvis Harvard-Smithsonian Center as long as Astrophysics An International, multi-agency mission of opportunity What is the Future of X-ray Binary Research Fields go through 3 phases: Discovery: mapping basic properties Widespread excitement rockets, UHURU to EXOSAT Underst in addition to ing: detailed study & physics Specialist interest only EXOSAT to Rossi XTE Tool: use underst in addition to ing to ask new questions Widespread interest begun by Ch in addition to ra, XMM-Newton Is X-ray binary research ending phase 2 Is phase 3 the testing of Extreme Physics Black Holes, Magnetars & Neutron Stars are cosmic laboratories as long as Extreme Physics: Gravity at the event horizon – Black Holes Frame dragging, metric in strong gravity – AGNs, BH binaries Magnetic fields with energy densities greater than an electron – Magnetars BQED=4.4×1013 g Densities of nuclear matter or beyond – ‘neutron’ stars

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Neutron star surfaces explore extreme physics have a hard surface enabling precision measurements have a thin atmosphere that imprints sharp atomic features in their spectra Enables spectroscopic tests of extreme physics are intrinsically X-ray sources deDeo & Psaltis, 2003 astro-ph/0302095 Space-Time curvature Gravitational redshift at neutron star surface Cottam J. Paerels F. & Mendez M., 2002, Nature, 420, 51 EX Hya: HETG R~500 Dvradial= 58.2 +/- 3.7 km/s Relative velocity only requires stability not absolute calibration +/-0.04, 10% errors Spectrum integrated over spin period, several bursts Spectroscopy: NS Equation of State Example: So far M only from orbit solution Spectroscopy adds: Gravitational redshift due to neutron star: zg ~ M/R Bhattacharya et al. 2006 ApJ + Doppler shift vs. phase ~12 km/s R x sin i Map R vs. M of EoS Van den Heuvel zg~ 0.3 czg~100,000 km s-1 1% errors ~1000 km/s -> R ~ 300 DE ~ 20 eV @ 6 keV DE = 2eV @ 1 keV zg spin Doppler shift Orbit solution

Extreme Magnetic Fields: X-ray Pulsars Polarized by: Emission process: cyclotron Scattering on highly magnetized plasma: Swing of polarization angle vs. phase measures: orientation of rotation axis on the sky & inclination of the magnetic field the case 45°, 45° (from Meszaros et al. 1988) Thanks to Enrico Costa Testing GR in strong field: bending of light in Galactic Black-Hole Binaries The Polarization angle from an accretion disk in the ‘Newtonian’ case is either parallel to the major axis of the sky-projected disk (positive) or parallel to the sky-projected disk symmetry axis (negative) If the field is strong enough polarization is altered by gravitational effects. The polarization plane rotates continuously with energy because of General Relativistic effects. This is a signature of the presence of a black-hole Stark & Connors, Connors& Stark, 1977, Connors, Piran & Stark, 1980. Polarimetry gives the orientation of an accretion disk on th sky Sunyaev & Titarchuk, 1985 Thanks to Enrico Costa Simulated observation Requirements as long as using Compact Objects as Physics Labs Compact object = ‘accelerator’ X-ray telescope = ‘experiment’ Observational Requirements: High spectral resolution R~500 precise measurements of zg, B High time resolution Dt = 100msec Resolve 10 phase bins in msec period Large area 5-10 sq.m: to collect enough photons: few x 103 counts in few x 103 ~1 eV spectral bins x 10 phase bins 106 photons to measure 10s 1% polarization Gratings need a good (<10” HPD) mirror Polarization Quantum critical B-field effects Crab = 104 ct/s/sq.m XRBs ~103 ct/s/sq.m Dreaming Extreme Physics Explorer A mission designed to study physics in the extreme environments provided by neutron stars in addition to black holes Not an X-ray astronomy mission A physics mission though utilizing X-ray astronomy techniques Achieves: Large collecting area High time resolution High spectral resolution Sensitive polarimetry Targets: Galactic neutron star in addition to black hole binaries, including magnetars, transients Long observations Microcalorimeters as timing devices Pulse rise time ~50 msec Event timing to ~5 ms Energy resolution <5 eV R>200 @ 1keV Con-X, NEW, DIOS goal 2 eV R=500 @1 keV = RGS, HETGS QE ~ 1 (down to ~0.5 keV) Ideal as long as neutron stars BUT: Count rate limit ~103 Hz Event duration ~100 msec Constellation-X cannot observe X-ray binaries with XRS SMALL ~1 cm2 area Overcoming microcalorimeter limitations: 1. Area Galactic X-ray neutron star binaries emit ~103 ct/s/sq.m Need ~107 counts/observation Observation should be small fraction of hours-days binary orbit: ~104s -> Area ~1 – 5 sq. m. = mirrors. Con-X mirrors weigh 280 kg m-2 too much as long as a MIDEX But: Good imaging is bad as long as microcalorimeter timing: Need to spread out the signal. ~1 arcminute HPD optics are about right. SOLUTION: microchannel plate mirrors: 3.7 kg m-2

Microchannel Plate Mirrors = LOBSTER optics Well developed (U. Leicester) Not XEUS Micropore optics Lightweight: 3.7 kg m-2 1/10 area/mass ratio of next lightest X-ray mirrors (ASCA/Suzaku foils) Plate-like, robust: fold/deploy easily Units ~1.7m dia. Deploy to 5m dia. 1 arcmin HPD: Demonstrated Bavdaz et al 2002 SPIE Not so bad: low background, confusion: can reach 10’s of AGNs High aperture utilization Thermal control Long Focal Length Needs ~40m focal length to get area f-number is fixed as long as grazing incidence mirrors 1arcmin ~ 1.5cm @ focal plane: good size as long as microcalorimeters Flight-tested light-weight deployable optical benches exist Able Engineering: UARS, GGC WDIND, GGS POLAR, Cassini, Lunar Prospector, IMAGE Slow slewing: long observations Overcoming microcalorimeter limitations: 2. Count rate Count rate limit is per pixel: 32×32 array can count at 1 MHz – as long as uni as long as m illumination C.f. 105 ct/s 10sq.m X-ray binary C.f. Con-X: 32×32, 2eV; NEW 32×32 2eV; DIOS 16×16 6eV Slightly larger arrays allow as long as aspect jitter: 5 arcsec rms -> ~10 arcsec 90% -> 5 pixels -> 42×42 array Pixel size ~ 500 mm (~ 2 arcsec) 50 meter focal length (to get needed area) 1 arcsec ~0.25 mm 1 arcmin beam size ~9 mm dia. ~ 2 x Con-X = DIOS DE = 2.36x 2m1/4 (kT2C/a)1/2 , C=heat capacity = a(pixel size)2 Trade-off: technical difficulty of larger arrays vs. DE

Optimizing Microcalorimeter Energy resolution Challenging spectral resolution: DE = 2eV, R = 500 @ 1 keV Easier to achieve over limited b in addition to width: thinner converter, lower heat capacity Divide high in addition to low energy signal between two detector arrays, few arcmin apart Tilt outer shells by ~5 arcmin ~10% of 1 keV graze angle Degradation of beam shape small compared with 1 arcmin HPD Also enables ~doubling of maximum count rate Keep polarimeter on axis – avoid instrumental polarization Focal Plane layout One Polarimeter Option: Micro Pattern Gas Detector Costa et al. Polarization from tracks of photoelectron: 50% modulation, 5.4 keV imaged by a finely subdivided gas detector, PIXI High time resolution: few msec High count rate: few 104 ct/s Put in ‘warm’ focal plane 10-20arcmin from mcalorimeter. Thanks to Enrico Costa A fast evolving technique Chip I (2003) 2101 pixel; pitch 80mm; 4 mm Ø Chip II (2004) 20000 pixel; pitch 80mm; 11 × 11 mm2 Chp III (2006) 105600 pixel: pitch 50 mm 15 × 15 mm2 Morover in Chip III each pixel has independent trigger in addition to capability to convert only triggered channels very fast read-out, few msec Thanks to Enrico Costa

MIDEX Scale Mission Mass Feasible mass budget: 10 m2 microchannel plate mirror: 37 kg Mirror support assembly: 37 kg Optical bench (extending to 40m): 40 kg Optical bench canister: 50kg Calorimeter & cryostat: 123 kg Spacecraft: 200 kg 20% reserve: 83 kg TOTAL: 585 kg Easily within MIDEX range Add small polarimeter, ASM mass Use excess to achieve a high orbit gives long continuous coverage Geostationary Continuous data contact: 104 ct s-1 x 64 bits/event = 0.1 Mbaud continuous But high background Not important as long as bright X-ray binaries May overload telemetry Challenges 2 eV 42×42 microcalorimeter array Mass production of microchannel plate optics Deployment of MCP optics Data rate: 0.1 MB continuous 40 meter optical bench Polarimeter Small cryostat; no cryogen All Sky Monitor as long as transients Science case development Spectro-timing, Polarimetric tests not fully developed Need simulations as long as specific sources Form Science Working Group Extreme Physics Explorer – A Next Generation RXTE 10 times area 100 times spectral resolution 1/1000 beam size 5ms time resolution polarimetry

Extreme Physics Explorer – A Mission of Opportunity NASA Appeals to: Fundamental Physics; RXTE community SAO [mirror partner, ops/data center] GSFC [mcalorimeter] DoE Fundamental Physics connection (&much cheaper than JDEM!) Potential International partners: With likely funding: Canada want a mission; Kaspi (McGill) pushing X-ray binaries Netherl in addition to s (SRON) want to fly a mcalorimeter as XEUS prep. Funding less clear: UK (Leicester) microchannel plate mirror Italy (ASI) U. Rome [polarimeter] Extreme Physics Explorer Time is ripe as long as X-ray emitting Compact Objects research to move to 3rd phase: Extreme Physics Physics-Astrophysics collaboration on Extreme Physics Need theoretical predictions of spectral features email elvis@cfa.harvard.edu if you want to join in The next accelerator Extreme Physics Explorer MIDEX scale: 500kg, deployed optics, 40m focal length, GEO orbit Microchannel plate Mirror: Area ~5-10 m2 at ~0.5 – ~10 keV [goal 20keV] ~10 x RXTE (PCA), ~500 x Ch in addition to ra (HETG, LETG) Arcminute imaging Long focal length ~40m Microcalorimeter: 2 42×42 arrays, 500mm pixels Low E: DE=2eV R=500 @ 1 keV, v +/-30 km/s High E: DE=6eV R=1000 @ 6 keV Polarimeter: TBD: several c in addition to idate technologies

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Green, Judy Freelance Children’s Book Writer

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