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Luigi Piro IASF-INAF Rome: 

Luigi Piro IASF-INAF Rome Workshop on WHIM and mission opportunities

Workshop on WHIM and mission opportunities: 

Workshop on WHIM and mission opportunities Scope of the meeting Take into account present (WHIM) mission profiles and related technology Discuss the status of the art in WHIM observations and theory and translate it in Derive requirements (organize a wg) to improve present profiles Discuss next steps and actions finilized to carry out a joint programme

Where are the baryons at z<2 gone?: 

Where are the baryons at z<2 gone? Detailed calculation from Big Bang Nucleosynthesis indicate 0.02 < h2Ωb < 0.06 At z = 3-4 the observations are in agreement: Lya forest At z~0 the baryon in stellar systems, neutral Hydrogen, X-ray emitting gas in cluster of galaxies is one order of magnitude less than the predictions. Where have the baryons gone? From models ~50% of baryons in hot or warm ionized IGM In the current models at z>2 the gas is diffuse. At z<2 large potential wells are produced and the gas is shock-heated. The gas is trapped in filaments by the gravitational pull of DM

Experiments / missions for WHIM: 

Experiments / missions for WHIM IMXS-IMBOSS (I-USA), MBE (USA) New proposals: ESTREMO (I), DIOS (J), NEW(H), Pharos (USA) Large interest from international community (but so far not successful, to be discussed tomorrow) Italy: WHIM science: key interest not only of astrophysical community but also of INFN (dark matter). IMXS-IMBOSS: large field / high resolution spectroscopy survey.

WHIM mission concepts: 

WHIM mission concepts Mitsuda, WHIM ws 2005


Italy: WHIM science: key interest not only of astrophysical community but also of INFN (dark matter, S. Vitale). IMXS-IMBOSS: large field (1sr) / high resolution (6 eV) spectroscopy survey of the sky. Grasp: (A*W = 2000 cm2 deg2). Feasibility assessment for allocation to ISS carried out. Activities stopped in 2002 given the ISS situation

ESTREMO Extreme phySics in Transient and Evolving cosMos The first observatory with very high resolution X-ray Spectroscopy, Polarimetry and Fast repointing : 

ESTREMO Extreme phySics in Transient and Evolving cosMos The first observatory with very high resolution X-ray Spectroscopy, Polarimetry and Fast repointing 


History The concept of Next Generation GRB Observatory (NG-GRBO) born in a meeting on EXIST in 2000 in US Sister satellite led by European partners to perform very fast ( 1 min) follow-up observations of GRB & transients localized by EXIST: X-ray cosmology wityh GRB Included as mission concept for a Italian mission in the proposal to ASI 2003 Evolved and expanded following two meetings in 2003 in Rome (with participants from Mi, Bo, Pa), in the Netherlands (SRON), and Turin with Alenia Spazio (pre-feasibility assessment of spacecraft fast slewing capabilities) NEW derivation from SRON. Potential merging with NEW and DIOS (workshop in Japan, 2005)

Scientific drivers: 

Scientific drivers Evolution of cosmological structures and sources in the Universe: X-Ray Cosmology: GRB as beacons, WHIM and dark matter, formation of first structures in the Universe Extreme physics (e.g. test of general relativity in Black Holes, GRB engines and progenitors)

New X-ray cosmology with GRB: 

New X-ray cosmology with GRB Identify high-z GRB and their primordial host galaxies Study the evolution of metals & star formation with z WHIM & dark matter Dark energy and extension of SN results at z>1

GRB as cosmological probes: 

GRB as cosmological probes Map the metal evolution vs z Simulations of X-ray edges produced by metals (Si, S, Ar, Fe) by a medium with column density NH=5 1022 cm-2 and solar-like abundances in the host galaxy of a bright GRB at z=5., as observed ESTREMO with an observation starting 60 s after the main pulse and lasting 60 ksec Fe Si S Ar

Mission profile: 

Mission profile   The mission is based on the combination of a wide field instrument, a narrow field instrument and fast pointing, i.e.: ·        Fast (<1 min) follow-up observations with ·        High resolution X-ray spectroscopy (De=2-4 eV in the 0.1-10 keV range) and ·        High sensitivity X-ray polarimetry devices ·        of independently localized X-ray transient phenomena in the sky with a wide field monitor in the X/hard-X range.   Each one is the state of the art in the field and the combination provides a unique and unprecedented capability.


TES+cryo-system Polarimeter WFC

Scientific goals: 

Scientific goals Estreme objects in our Universe characterized by very large energy release over short time scale (minutes-hours): Gamma-ray Bursts, Massive Black Holes, Neutron stars, Supernovae explosions, Flare stars Evolution of the Universe: the new X-ray cosmology by using the brightest and most distant explosions, the Gamma-Ray Bursts

GRB (afterglows ) as bright background source for WHIM absorption studies: 

GRB (afterglows ) as bright background source for WHIM absorption studies (Piro et al, ApJ 05)

WHIM absorption lines towards GRB afterglows : 

WHIM absorption lines towards GRB afterglows Fraction of the total fluence of the afterglow of a GRB in the interval t0=60 s and t, for a decay power law with slope –1.3 Similar numbers from SWIFT: Corsi’s talk

Dark matter & WHIM: X-ray forest : 

Dark matter & WHIM: X-ray forest  Structure simulation from Cen & Ostriker (1999) Simulations of WHIM absorption features from OVII as expected from filaments (at different z, with EW=0.2-0.5 eV) in the l.o.s. toward a GRB with Fluence=4 10-6 as observed with ESTREMO (in 100 ksec). About 10% of GRB (10 events per year per 3 sr) with 4 million counts in the TES focal plane detector

Comparison of main parameters for WHIM absorption line detection at 0.5 kev for this and present and future missions : 

Comparison of main parameters for WHIM absorption line detection at 0.5 kev for this and present and future missions The relative fluence S/S0 of the afterglow is derived assuming a decay slope of 1.3, with an integration of about 100 ksec, starting at 60s for this missions and at 11 hrs for the other missions. M is the factor of merit = Aeff*h S/DE for line detection: EWmin= Ks /kM, when Ks is the number of s required for the detection (Ks=5)

WHIM in absorption and emission: 

WHIM in absorption and emission Focal lenght 4 m, (1.2’ per mm), with pixel 500um, and radial geometry would give radius of about 10’ for 1000 pixels (4.5’ for 200 pixels) Possibility to study the same WHIM filament first in absorption and then, when the GRB afterglow has disappeared, in emission


WHIM emission lines detection: some estimates Filament completely filling the FOV: NL  (Aeff) x (FOV) x T; The contribution of photons from XRB and Galactic emission is determined by the energy resolution E: Nc  E x (Aeff) x (FOV) x T; S/N = NL/Nc0.5  [ ((Aeff) x (FOV) x T) / E ]0.5: a larger Aeff x FOV increases the number of counts for a given integration time, but a higher energy resolution gives a better S/N.

Baseline Requirements (I): 

Baseline Requirements (I) Wide-field monitor: Localization and study of GRB & X-Ray transients 2-300 keV; 2-3 arcmin resolution; solid angle > 2 sr such that >50-100 GRB per year and a similar number of transient sources) Detector Technologies: CdZnTe, Si, Lobster Small omnidirectional spectrometer for GRB spectrum (Epeak)

Baseline Requirements (II): 

Baseline Requirements (II) Autonomous fast follow-up 10-100 seconds following the transient position from on-board x-ray localizator (ala SWIFT) 1.5 ton class in low earth orbit (VEGA launcher, Malindi ground station) Launch in the 2012 frame - X-ray optics of 1000 cm2 eff.area (8xSWIFT) TES microcalorimeters (DE=2 eV at 1 keV) AND KHz count rate (to observe Crab-like sources!!) For a typical X-ray afteglow, about 100.000 cts will be secured starting from 50 sec X-ray polarimeter with MDP 5% for Crab-like

Requirements for NFI-TES: 

Requirements for NFI-TES Energy range: from 0.1 to 10 keV Energy resolution: 2 eV below 1 keV (goal 1 eV), around 3-4 eV at 6 keV Number of imaging pixels: >100, with a goal of 1000 Size of pixel (depending on the plate scale): 200-500 um Field of view (assuming a 4 meter focal length, a 500 u pixel and radial geometry): 8 arcmin diameter for 200 pixels, 18 arcmin diameter for 1000 pixels Count rate vs flux conversion: for a power law with photon index=2 and Nh=2e20 cm-2, 1 mCrab source would give about 10 cts/s in the 0.1-5 keV range.  Maximum count rate: high enough to allow spectral measurements of a Crab-like source, corresponding to about 20.000 cts/s (for a low-energy absorption of 2e20 cm-2). Assuming a PSF with Half Energy Width of about 1 arcmin, and a pixel size of 250 um, the count rate per pixel would be about 400 cts/s, compatible with TES performance. The trade-off of pixel-size vs field of view is optimized with a detector in which the central part has pixels of 250 um size, and the outer region (devoted to background and WHIM emission line detection) has 500um pixel size.

Spacecraft, launcher and Orbit : 

Spacecraft, launcher and Orbit Time to to slew to 60 degrees: 20 sec 3-axis stabilized, Pointing accuracy: 1’ Post facto attititude reconstruction: <20” Zone of sun avoidance: TBD Orbit: LEO preferred for lower bkg and payload mass, but HEO is not ruled out Launch mass: 1500 kg P/L mass: 600 kg P/L power: 800 W on-board memory: upto 250 Gb downlink in S and X bands upto 512 kbps and 210Mbps respectively during the passage compatible with VEGA; Soyuz, Delta and other launchers,

VEGA launch capability: 

VEGA launch capability

Allocation in VEGA : 

Allocation in VEGA

New developments: 

New developments Merit of present configuration (extension to the 7 kev range: Fe line, polarimetry). WHIM in emission and absorption Increase the fov: good for whim emission, (grasp), relax somewhat requirements on wfm . Price to pay: E>3 keV, complexity of TES central part (need smaller pixels to avoid pile up).

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