X-Ray Timing & Spectroscopy on Dynamical Timescales From

X-ray Timing & Spectroscopy on Dynamical Timescales from Microseconds to Years

Paul Ray (U.S. Naval Research Laboratory)

Steering Committee: Colleen Wilson-Hodge (MSFC) Tom Maccarone (Texas Tech) Zaven Arzoumanian, Keith Gendreau (GSFC) Deepto Chakrabarty, Ron Remillard (MIT) Peter Jenke (UAH), Marco Feroci (INAF), Silvia Zane (UCL), Soren Brandt (DTU) , Alessandra DeRosa (INAF), Margarita Hernanz (IEEC), Anna Watts (Amsterdam), Kent Wood (NRL), John Tomsick (Berkeley), Laura Brenneman (CfA), David Ballantyne (GA Tech), Mike McDonald (MIT), Adam Goldstein (MSFC), Abbie Stevens (MSU), Enrico Bozzo (Geneva), Dieter Hartmann (Clemson), Bernard Phlips (NRL), Marc Christophersen (NRL)

+ > 150 members of SWG The STROBE-X study is funded by NASA Why a Flexible, High-Throughput Observatory?

• The high-energy sky is highly dynamic – requires catching the right source at the right time – Necessitates both wide field monitoring and the ability to repoint quickly (as RXTE and Swift have demonstrated) • Critical capability in the era of time domain and multi-messenger astronomy • Large areas with low dead time access the shortest timescales • Both soft and hard X-ray bands are needed to accurately measure the continuum spectral shape, constrain absorption, and understand the relationship between thermal and non-thermal components

Figure from Ron Remillard HEA Time Domain Desirati 2020 Courtesy Daryl Haggard

Discovery & Monitoring Rapid Response High Time Resolution • All Sky Monitor •Rapid slew (< hr) • Sub-ms timing • Science drivers: •Science drivers: • Science drivers: GW cntrparts, GW cntrparts, Strong gravity, GRBs, SNe shock GRBs, stellar neutron star breakout, flares/space physics, accretion, tidal weather, XRB/AGN disruptions transients physics, QPOs • ~Daily Cadence •High Availability • High Sensitivity Coronal Black Holes on All Mass Scales Emission T ~ 109 K Relativistic How do black holes form and grow? Reﬂection Distant • Understand the spin distribution of black holes, using Reﬂection

three complementary approaches: HFQPOs, Rin continuum fitting and reflection fitting all accessible T ~ 107 K with STROBE-X – Critical for understanding systematics of each technique 100 How do black holes accrete and form jets? NuSTAR+XMM

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a ATHENA in 100 s with STROBE-X L • Also, variable disk winds, QPOs, state changes, disk- 0.1 STROBE-X jet connection and more! 110 Energy (keV) Neutron Stars Is there new physics at the core of neutron stars? • Fully determine the ultradense matter equation of state by measuring the neutron star mass-radius relation using >20 pulsars – Measurements spanning low to high masses are critical to nail down the precise EOS • Burst oscillations, thermal surface emission, and accretion-powered pulsations all will be accessible – Multiple techniques and many systems mitigate systematic errors • Global oscillation modes would open a new window on NS interiors Rapid and ExtremeLong GRBs Explosions— Core-Collapse SNe

• Gamma-ray bursts and • X-RayKey Flashes WFM (XRFs) Features: • Jet Cocoons

X-ray flashes Time (seconds) • Choked bursts 1e+02 1e+03 1e+04 1e+05 1e+06 • Arcmin localization12 allows • X-ray afterglow 1e−10 X−ray 14 H − 2.0 mag • LIGO and LISA EM optical follow up withJ − 1.5 mag single z’ − 1.0 mag i’ − 0.5 mag 1e−11 r’

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• Large instantaneousA FOV • Tidal disruption events 20 1e−13 probes rare22 events • Supernova shock 1e−14 • Autonomous24 repointing of

1e−03 1e−02 1e−01 1e+00 1e+01 breakouts Time (days) pointedGuelbenzu+ instruments 2011 and fast

• X-ray bursts and St14roberesponse-X to ground TOOs superbursts • 300 eV spectral resolution • Stellar flares ansensitived to lines and • Much more… absorption features Tidal Dis•ruContinuousption eventEve datant allowss timing studies See Poster on science case and the broader portfolio Katie Auchettl The Ohio State University/CCAPP

Email: [email protected] STROBE-X Instrument Concept Large effective area >5 m2 @ 6 keV Wide Field Monitor X-ray Concentrator Array (0.2-12 keV) (2-50 keV)

• STROBE-X combines the strengths of NICER and LOFT: High throughput X-ray timing with good spectroscopy • All components are already high TRL Large Area Detector • Highly modular design improves reliability at (2-30 keV) reduced cost and allows easy scaling. X-ray Concentrator Array

• Scaled up version of NICER concentrators with NICER SDDs – Focal length of 3 m for enhanced throughput >2.5 keV – Inexpensive single-bounce foil optics: large areas w/ low background – Energy resolution: 85-175 eV FWHM NICER concentrator – 80 XRCA units gives effective area @ 1.5 keV: >2.0 m2 ~XRCA concentrator (> 10X NICER) • Low background, high throughput • Enables high time resolution observations of the faintest sources, both extragalactic and galactic • Sensitive timing and spectroscopy to thermal emission and iron lines Large Area Detector

Silicon Drift Detector (SDD)

Glass micropore collimator

LAD module

• SDDs and lightweight microcapillary plate collimators developed for ESA’s LOFT M3 & M4. – Energy resolution: 200–500 eV FWHM – 60 modules gives effective area @ 10 keV >5 m2 (~10X RXTE) • High time resolution and good energy resolution over the 2-30 keV range – Best sensitivity to QPOs; most prominent in harder X-rays – Sensitive to non-thermal emission and Compton hump Wide Field Monitor

• SDDs similar to LAD with finer pitch • Energy resolution: 300 eV FWHM • 1.5D wide-field coded mask imager • Two cameras rotated by 90° give 2D positions • Four camera pairs give instantaneous FoV: >1/3 of sky; 50% of sky accessible to LAD • 1 day sensitivity of 2 mcrab, with source localization of 1 arcmin • Continuous viewing, not scanning gives sensitivity to transients from milliseconds to years • Identifies new transients and source states for main instruments, while monitoring long-term source behavior for a large fraction of the sky • Onboard processing can trigger autonomous repoint for GRBs, superbursts, etc. Instrument Design Lab (Nov 2017) • Developed detailed instrument design • Optical bench made out of composite structure, reducing mass and improving stiffness and thermal distortions • Deployment mechanism for LAD panel designed, no concerns • Detailed cost model for instruments Mission Design Lab (April 2018)

• Complete spacecraft design • Moved WFM to top, removing need for sunshade • Control Moment Gyros (CMGs) give 15 deg/min slew rate • Includes autonomous repoint capability for WFM triggers • TDRSS Ka band gives 300 Mbps telemetry downlink • TDRSS S-band gives rapid burst alerts to ground and TOO commanding • Full lifecycle costing ($880M) well under Probe class cost cap with over 10% margin – International contributions would reduce this further (none taken for granted so far) • Huge collecting area, fast timing, and good spectral resolution, addressing fundamental questions in accretion, dense matter, black hole formation and evolution • Based on existing technology and builds on experience with NICER and LOFT, enabling confidence in cost estimates at this early stage. Highly modular design allows easy scaling. Comfortably under Probe-class cost cap • Will serve a large community in a decade of time-domain and multi-messenger astronomy with complementary capabilities to the large high spectral and spatial resolution missions – Active SWG with over 150 members open for all to discuss science impacts of the mission Follow us on Twitter (@STROBEXastro), Facebook, and https://gammaray.nsstc.nasa.gov/Strobe-X/ BACKUP Instrument Parameters Technical Context from LOFT and NICER

• Solid state detectors like Silicon Drift Detectors can provide high time resolution with low dead time and CCD- like spectroscopy • Thin, light micropore collimators a much lower mass and volume than traditional X-ray collimators, enabling large missions and modest cost • Lightweight, inexpensive foil optics can provide large collecting area with low background at low cost NICER

• PI: Keith Gendreau (GSFC) • Operating on ISS since June 2017 • Already discovering new millisecond pulsar pulsations, burst phenomenology, spectral timing studies, AMXP orbit, responding to BHXB and HMXB TOOs, and much more! • Demonstrating feasibility and robustness of inexpensive optics and commercial SSDs • Single bounce concentrators + • Nearly all data are public 2 weeks after SDDs cover 0.2–12 keV band observation • 2 arcmin radius single pixel FOV • 56 identical units, 2-axis pointed eXTP

• China-Europe collaboration under study with 4 instruments – Spectroscopic Focusing Array (SFA), with up to 0.8 m2 in 0.5–10 keV – Polarimetry Focusing Array (PFA), 900 cm2 in 2–10 keV – LAD, 40 modules = 3.4 m2 in 2–30 keV – WFM, 3 cameras • Goal is 2025 launch • Not yet approved in China and European contributions not yet funded • Factor of ~2 smaller than STROBE-X • Long focal length mirrors likely mean slower slewing and TOO response times GRB Science with STROBE-X

• WFM wide FOV will detect many bursts, at softer energies that other instruments – Arcmin localizations promptly downlinked for >100 GRBs/year – Autonomous slewing to catch plateau phase • LAD could catch magnetar pulsations or Fe lines – 300 eV resolution gives capability to see spectral features and thermal components – Large number of soft bursts, XRFs and high-z GRBs • ~30 XRF/year • ~1 GRB/year at z>6 Simulation of the transient absorption feature in the X-ray energy band detected by BeppoSAX/WFC in the first 8 s of GRB 990705 as would be measured by the STROBE-X/WFM (Amati et al., 2000). STROBE-X spectra on a dynaUnfolded Spectrummical timescale! 3 Crab 10

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jsteiner 18−Sep−2017 01:50 Cost Estimate

WBS Source Point Reserve (25% on Est + Reserve • Class B mission rules (dual string design, high Estimate Phases A-D) ($M) priority, low risk) 1.0 Project Management Wrap 29.2 7.3 36.5 • FY18 dollars 2.0 Systems Engineering Wrap 29.2 7.3 36.5 • Phase A begins Oct 2023 3.0 Safety & Mission Assurance Wrap 18.2 4.6 22.8 • Launch 2031 4.0 Science/Technology Wrap 36.5 9.1 45.6 • PRICE-H instrument and spacecraft component costs 5.0 Payload IDL 192.7 48.2 240.9 • Standard MDL “wraps” for other WBS items 6.0 Spacecraft MDL 172.0 43.0 215.0 – We increased mission ops cost above this to be 7.0 Mission Ops Team 83.0 0.0 83.0 comparable to Fermi and HQ guidance 8.0 Launch Vehicle/Services NASA HQ 150 0.0 150 • Require 25% reserve on Phases A-D • Fits in Probe class $1B cost cap with over 10% 9.0 Ground Systems MDL 12.3 3.1 15.4 margin 10.0 I&T MDL 20.8 5.2 26.0 • Assumes only NASA funding 11.0 E&PO Wrap 5.5 1.4 6.8 – International contributions are very likely to Phase A Estimate 2.0 0.5 2.5 reduce NASA cost TOTAL 751.3 129.7 881.0