X-Ray Spectroscopy in Astrophysics Luigi Piro Istituto Astrofisica Spaziale Fisica Cosmica, Roma INAF

Summary X-ray spectroscopy, the present instrumentation (CCD, gratings) Opening a new window in Cosmology and Extreme physics Enabling technology: TES microcalorimeters Future missions: Xenia, IXO

X-ray spectroscopy in Astrophysics Cryogenic microcalorimeters (T=100 mK) with high spectral resolution open a new observational window in Astrophysics and Cosmology. Example of astrophysical plasma (107K) observed with: * TES microcalorimeters (DE=2 eV, IXO, Xenia, DIOS) *Si-base microcalorimeters (DE=6-8 eV: ASTRO-H) *CCD (DE=100 eV:XMM)

Science Drivers What are the fundamental physical laws of the Universe? Matter under extreme conditions How did the Universe originate and what is it made of? The early Universe The Universe taking shape The evolving violent Universe

Structure Formation HOW ? z 10 1 Most of the baryon of the Universe are locked in large scale, low density structures visible only in X-rays z High resolution spectroscopy and spatial resolution, wide field in emission 10 1 GRB as cosmological beacons: fast reaction, high res. absorption spectroscopy Structure size Stars Galaxies Clusters Filaments

XENIA Cosmic chemical evolution of baryons Undergoing US Decadal Survey 2010 As Medium Size Mission International consortium of Institutes from US, Eu, Japan

XENIA: Mission and Payload HARI: High Angular Resolution Imager 1000cm2@1keV 0.3-8 keV CCD Field=1.4° ang.res=10” constant Low bkg: LEO equatorial Autonomous fast pointing in 60 s 2 tons TRL4 Decadal Survey medium size CRIS: Cryogenic Imaging Spectrometer 1000cm2@0.5keV 0.1-3 keV TES DE<2.5eV Field=1.0° ang.res=3’ TED: Transient Event Detector ¼ of the sky, 3’ localization 8-200 keV

Tomography of the Universe: the X-ray forest from the Cosmic Web with GRBs From 150 GRBs with afterglow Fluence>2 10-6 cgs ~200s OVII-OVIII filaments in 5 years

3D mapping of the Cosmic Web Model, Dz=0.01 Detected, OVII+OVIII in emission, 5 s, 1 Ms 4°x4° Pixel size is 3 arcmin >100 detecttions at five sigmas in the lines Down to overdensities of 100

GRBs as cosmological probes GB090423: z=8.2 ! GRBs as cosmological probes About 90% have a X-ray afterglow, 20-40% are dark High z events are dark (Lya forest absorption at z>6) X-ray redshift Observing a mid-bright GRB afterglow with a fast (min.) pointing XENIA yields 106 X-ray photons, and 103 cts in 1 eV resolution bin Out of 400 =>Golden sample of >250 afterglows with high res. X-ray spectra: redshift, metals in host-galaxy and close environment from local to high-z universe

Narrow abs lines from ISM in our own host galaxy Bright galactic binary (1820-303) observed with Chandra grating (Yao and Wand 2006)

Metal and ISM evolution with GRB Metal enrichment in the environment of massive stars upto z>6 ISM of the host galaxy, kinematical studies of the outflows Resonant absorption lines from GRB host galaxy at z=1 X-ray metal edges from a GRB nearby environment at z=7

IXO International X-ray Observatory Undergoing Dedadal Survey 2010 and ESA Cosmic Vision As Large Mission International consortium of Institutes from US, Eu, Japan

IXO 5 year life; 10 years on consumables Deployable Metering Structure w/Shroud Flight Mirror Assembly X-ray Microcalorimeter Spectrometer Wide Field X-ray Imager Hard X-ray Imager X-ray Grating Spectrometer High Time Resolution X-ray Polarimeter Spacecraft Bus Module Atlas V 551 Medium Composite Fairing 5 year life; 10 years on consumables

Comparing IXO to Existing Missions The improvement of IXO relative to current X-ray missions is equivalent to a transition from the 200 inch Palomar telescope to a 20m telescope, and at the same time shifting from spectral band imaging to an integral field spectrograph

Science Drivers Matter under extreme conditions: Supermassive Black Hole Growth Matter Orbiting a Black Hole Neutron Star Equation of State Formation of Structures: Nature of Dark Matter and Dark Energy Cosmic Feedback Missing Baryons Observatory Science (Life Cycles of matter and energy) Origin and Dispersion of Elements Particel Acceleration Planet Formation Stellar Magnetic Fields

Black Hole Spin & Growth Non-spinning Rapidly-spinning Simulation redone by Laura Brenneman, 300 ksec on MGC-6-30-15-like AGN. Note that this source is only moderately above average in overall flux, its iron line is one of the strongest available. To get Order(100) such sources, we will go down an order of magnitude in iron line flux – however, the 300 ksec shown here is extreme overkill to show the overall effect. An adequate measurement could be done in 15-20 ksec. On average, expect 50 ksec observations of 100-200 sources to get spin distribution (5-10 Msec). a=0.93 is the expected maximum spin value, based on theoretical calculations involving the drag of the disk on the BH; 0.7 is an intermediate value, and a=0 is the non-spinning case. IXO will measure relativistically-broadened iron line emission, measuring the black hole’s spin.

Determining M,R separately IXO XMS spectrum of x-ray burst Slowly rotating (45 Hz), 1.4 M neutron star Fe XXVI Ha for zGR = 0.35 – determines M/R Doppler shifts cause line splitting – width depends on R 120s exposure for 1 Crab burst Can determine M and R via spectral signatures due to pressure broadening, relativistic kinematics (rotation, Doppler shift, time dilation, beaming), and general relativity (light bending around the star, gravitational redshift, frame dragging). Simulation of what we would see with IXO for these line shapes, during a burst, and including the fact that during the rise of the burst the emission is not uniform but starts at a particular hot spot often thought to be near the pole, and Then spreads around into a band before enveloping the entire star. Here we see that the difference between R=11.5 and R=9 is easily detected.. Note the exposure time – 120s. The IXO provides such a large increase in area for high resolution spectroscopy That we can do this quickly, for a large number of NS, which may well cover a large range of mass. For more rapidly spinning bursting neutron stars IXO High Time Resolution Spectrometer using out-of-focus Silicon Drift Diodes can handle count rates as high as 10^6 per sec with 10's of microsec timing capability. 18

Neutron Star Equation of State Insufficient time to discuss any or all of the models which predict various tracks for NS mass vs radius, nor time to discuss the regions of the plane already constrained by GR, causality, etc Since accreting NS can provide a range of NS mass, envision just 3 IXO measurements (red ellipses) of ns masses and radii with ~10% precision as shown in the slide. Potential is very high to discriminate among the competing models and extend QCD with confidence to super high density regime. Lattimer & Prakash 2007

TES microcalorimeter

Manufacturing and testing TES on silicon membrane with Pulsed Laser deposition +deep RIE - Ir/Au, Ti/Au or Mo/Au (total thickness about 100 nm) onto SiN (1 um) suspended membrane - Absorber (Au, Au/Bi, Cu/Bi, Sn, few um thick) growth on the TES substrate - Pixel about 250x250 um Manufacturing facility at INFN Genova Cryo testing facility at IASF-Roma Cryo system based on liquid-free Pulse –tube + ADR down to 50 mm (as in-flight)

Detector Sizes and Single Pixel results Ferrari, Gatti et al. INFN and Genova Univ. EFWHM = 3.6 eV INFN and Genova Univ. Bandler et al., J Low Temp Phys, 151, (2008) TMU-ISAS Akamatsu, LTD13, in press, (2009) Hoevers et al., J Low Temp Phys, 151, (2008) SRON

TES microcalorimeter as flight instrument Goal: kpixel array with 2 eV resolution Italy: consortium led by IASF-RM/INAF and INFN/Univ. Genova, IFN-RM/CNR, INAF-Pa, TAS-Mi Co-Piship for IXO instrument in International Consortium with SRON, Goddard/NASA, JAXA

(bond pads for 256 channels only) TES Arrays Multiplexing technique is necessary to minimize the heat load caused by thermal conduction through the harness to the cold finger (thousand wires). The array is powered and read by rows or by columns using different Multiplexing methods: FDM (sinusoidal excitation) TDM (switch ON/OFF line by line) CDM (inversion bias polarity) 32x32 NASA GSFC – IXO/XMS (bond pads for 256 channels only) Eckart, Doriese, SPIE Newsroom , 2009 FDM technique: Pixels are AC-biased (line by line) Summing node (column by column) De-modulation by the same frequency to recover the pulse

Summary Future X-ray missions (IXO,Xenia) based on new generation of Transition Edge Sensor microcalorimeters (<2 eV resolution, high count rate capabilities, imaging) enabling spatially resolved high spectral resolution Fundamental issues addressing cosmology in X-rays and extreme physics