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WF-MAXI soft X-ray transient monitor on the ISS
Osaka GWPAW, Jun18, 2015 1
Nobuyuki Kawai, Hiroshi Tomida, Tatehiro Mihara, Yoichi Yatsu, Shiro Ueno, Atsumasa Yoshida, Masahi Kimura, Makoto Arimoto, Motoko Serino, Takanori Sakamoto, Hiroshi Tsunemi, Takayoshi Kohmura,
Hitoshi Negoro, Yoshihiro Ueda, … (Tokyo Tech, JAXA, Osaka University, RIKEN, Aoyama
Gakuin University, Nihon University, Kogakuin University, Kyoto University, Chuo University)
“Searching for X/γγ-‐ray Counterparts of GW Sources” a subgroup of MEXT Grant-‐in-‐Aid for Scien9fic Research on Innova9ve Areas
“New Developments in Astrophysics Through Mul9-‐Messenger Observa9ons of Gravita9onal Wave Sources” (Grant Number 24103002)
i
A01: Searching for X/γ-ray Counterparts of GW Sources
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Large-‐‑‒Sky Short X-‐‑‒ray �ransient �onitor�
�etailed St�dies�
S�ift�(X-‐‑‒ray�������
Soft X-‐‑‒ray Large Solid A�gle Camera����ard X-‐‑‒ray �o�itor�
Co��ter�arts sear���
A0���� analysis�
Alerts
Alerts
A0��theory�
A0��Opt, NIR��
A03�neutrino �
AS���-‐‑‒��(Ｘ-‐‑‒ray��
�ro��d �ased��eles�o�es�
MAXI (Monitor of All-‐sky X-‐ray Image) on ISS
3
Direction of Motion
MAXI
GSC-‐H
GSC-‐Z
Earth horizon
ISS orbital mo9on
SSC-‐H -‐Z
• Only X-‐ray ASM now • Since 2009/08~ • Ops extended
~2018/03
Gas Slit Cameras (GSCs)
4
Anode direction Scan
dire
ctio
n GSC Detector: Proportional Counter Energy: 2.0-30.0 keV Effective area: 5350 cm2 (Total) Field of View: 80 x 3 deg2
Anode direction Scan direction
BBEEXX TTIIMMEE
Slit
Slat collimator
Field of view
Scan direction
Num
ber o
f photons
GSC all-sky map (4.1 years).
Red: 2-4 keV, Green: 4-10 keV, and Blue: 10-20 keV. The X-ray binary pulsars appear in blue, supernova remnants in red.
Yellows are low-mass X-ray binaries. More than 500 sources are detected.
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GSC all-‐sky
MAXI J1659-‐152 (GRB 100925A)
MAXI 1543-‐564 MAXI 1836-‐194
MAXI 1305-‐704 MAXI J1828-‐249
Blackholes discovered by MAXI
MAXI J1910-‐057 (Swi] J1910.2-‐0546)
55500 56000 56500 2009.8 2014.4
• Since 2009 August, 12 BHCs were discovered. 6 out of them were discovered by MAXI.
MAXI blackholes Negoro et al. (2014)
MAXI J0158-744 – Nova ignition
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• Soft X-ray Transient ( emission only < 5 keV, duration < 1200s )• Near the edge of Small Magellanic Clouds (SMC)• Swift / XRT & UVOT identified it to a star (B~15mag.)
Rapid nova Morii et al. (2013)
Why search soft X-ray transients? • γ-rays/hard X-rays
– well studied by Swift – short GRBs ‒ most probable EM counterparts
for BNM, but too few • optical/NIR
– kilonova ‒ likely, but faint, need big telescope – high background transient event rate: AGN,
stellar flares, SN, … • Soft X-rays
– unexplored – suggestive signatures in short GRBs (EE) – theoretical suggestions (Nakamura et al. 2014,
Kisaka et al. 2014, 2015) 8
Short GRB 050709
6/18/15 9
Chandra HST
Fox et al. 2005
z=0.160 Dwarf irregular galaxy SFR = 0.2 Msun/yr
HETE-2
Short hard pulse
so> extended emission
MAXI GRBs and transients (2—20 keV)
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●: only MAXI ●: MAXI + other
h_p://maxi.riken.jp/grbs/ Serino et al. (2014)
JJeett
EEjjeeccttaa
SShhoocckk
SShhoocckk
EEnneerrggyyiinnjjeeccttiioonn
NNuucclleeaarr ddeeccaayy ppoowweerreedd
LLeeaakkiinngg tthheerrmmaall XX--rraayyss
hheeaatteedd//sshhoocckkeedd tthheerrmmaall XX--rraayyss
modified from Kisaka, Ioka & Takami 2015
EEnnggiinnee ppoowweerreedd ((jjeett,, ddiisskk wwiinndd,, mmaaggnneettaarr ppooyynnttiinngg fflluuxx))
Possible soft X-ray production
Kisaka, Ioka & Nakamura 2015
Possible soft X-ray production
10-14
10-12
10-10
10-8
10-6
103 104
Flux
[erg
/cm
2 /s]
Time since GRB 130603B [s]
GRB 130603B @ 100 MpcPlateau emission
Reflection (ε=10-3)ISS-Lobster
Swift XRTeROSITA
((ssccaatttteerreedd)) ppllaatteeaauu eemmiissssiioonn ffrroomm jjeett
BH Binary X-ray Burst
Log luminosity (erg/s)
Long GRB
Low luminosity
GRB
Short GRB
SN shock breakout
Nova ignition
Tidal Disruption
MAXI MAXI WF-‐MAXI
X-ray transients: L-∆t
13 0 1 2 –3 –2 –1 –6 –5 –4
5 6 7 2 3 4 –1 0 1 log seconds
log days
42
44
46
48
50
52
38
40
Short soft X-tray transients
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Tidal disrup9on Supernova /GRB shock breakout
Merging neutron star binary
Supergiant fast X-‐ray transient
è short GRBs associated with
GW events
Or, priviously unknown soft X-ray transients
Desired improvements for GW events 1) Large sky coverage and long observing 9me, needed for higher
probability to find transient events 2) Early start of the mission coincident with the start of GW
observa9ons 3) Con9nuous ground link, needed for prompt transient alerts 4) X-‐ray camera in energy range including the so] X-‐ray band
à X-‐ray CCD camera (SLC) and scin9lla9on detector (HXM) on the ISS. also low-‐cost, low-‐risk
u Balloons or sounding rockets do not meet requirement 1 u Epsilon-‐launch satellite does not meet requirement 2 u Small satellite requires extra cost for requirement 3
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Changes from present “MAXI” • Instantaneous sky coverage 2% è 20%
– More short (<92 min), rare events • Slit-Slat è Coded mask
– More (×10) photons from short events – Better localization for short/variable events
• Proportional counterèCCD – Much simpler calibration for photon positions – Improved spectral resolution 1.2 keV à0.15 keV – Lower energy threshold 2 keV à0.7 keV
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SLC Soft X-ray Large solid angle Camera
• Hamamatsu CCDs • 16 chips per camera • Cooled to ‒100 C° using
mechanical cooler • Cooler model same as
Astro-H/SXI • Field of view 45°×45° • FWHM, single camera
• Optical blocking filter (Al+polyimide) on top
• Al coating on chip • painted black on chip sides • prototype built in 2014,
under testing
380mm
SHI mechanical cooler
CCD
“Wide-‐Field MAXI” on ISS
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MAXI JEM EF
Direc9on of Mo9on
goals • Counterparts for GW sources (adv. LIGO/VIRGO, KAGRA) • First large-‐sky monitor for short so> X-‐ray transients
field of view ≈ 20% of the sky (covers 80% sky in 92 min)
Instruments So] X-‐ray Large Solid Angle Camera (SLC: 0.7–10 keV) Hard X-‐ray Monitor (HXM: 20 keV–1 MeV)
sensiZvity 50 mCrab /30 s (SLC) pos. accuracy 0.1° pla[orm ISS/JEM (Selec9on in 2014, opera9on 2018–)
N. Kawai + WF-‐MAXI Team
WF-MAXI • Applied for ISAS Small Project (Feb 2014)à Not selected
– （Budget 1 billion JPY/year for ALL the small projects）
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• X-‐ray Counterpart of GW: high risk • Too expensive (5 bn yen in 5 years, while ISAS has only 1 bn/yr for all the small projects )
Change of the bus Change the bus (infrastructure for mechanical, thermal, power, communica9on and other auxiliary supports) from Full scale (MAXI-‐class) to Medium size (iSEEP): (scale reduc9on with some science descop. ==== background ==== l For early start of the mission (requirement 2), Simplify the mission to shorten the
period for selec9on and development l Was too expensive as an ISAS “Small Project” of 5 years
Full-‐scale bus itself costs a lot (60% of the total cost), and therefore reduc9on of science instruments makes only minor cost reduc9on
l Medium-‐size bus (iSEEP) has large uncertain9es in specifica9ons last year, in par9cular thermal design, therfore we did not consider in the last years proposal.
l With the progress of design and analysis of iSEEP, now we can use it for WF-‐MAXI.
è for these reasons, we changed the design to use the new medium-‐size bus, and
aim for re-‐applying for the ISAS Small Project Category B ( total cost ≤ 1 bn JPY) Advantages: Lower cost, shorter development period Disadvantages: Compromise of science output
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Change of bus: Kibo Medium-‐size bus “iSEEP”
Ø Re-‐usable. Could be replaced by other mission. Plan for building two modules.
Ø Newly developed, not used in orbit yet Ø Can accommodate one or two missions Ø Total a_achable mass up to 200 kg Ø Total electric power up to 400W Ø Ethernet (2 ports) Ø Interface ≈20 C° (ac9vely controlled)
Transport iSEEP to ISS
WF-‐MAXI development and transport to ISS
Assembled by astronaut on ISS
Mounted on JEM/EF using robot arm
59cm
sketch Use sequence
In case of trouble, could be fixed by astronaut on ISS
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WF-MAXI on iSEEP • Accommoda9on design under way • only one SLC (was 4 SLCs and 4 HXMs) • Reduc9on of field of view by factor ≈2。
22 Applied for JAXA/ISAS “Small-‐scale Project”
(February 2015)
iWF-‐MAXI (iSEEP Wide-‐Field MAXI on ISS)
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MAXI
Direc9on of Mo9on
Scientific Goals
Detect, localize & alert soft X-ray transients GW counterparts, X-ray binaries, GRBs, Supernova shock breakouts, Tidal disruption events, Novae, Stellar flares, …
Monitor field ≈10% of sky instantaneous (80% in 92 min) instrument SLC (CCD+coded mask, 0.7‒10 keV) sensitivity 100 mCrab /100 s localization ≈ 0.1° Platform ISS/JEM (Selection in 2015, operation 2019‒)
JEM Exposed Facility
iWF-‐MAXI
Sky coverage from ISS/JEM
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!"!#$%!&'(!'&)*&#+,&
-*&,*&.&*&
& && &
&&& &&& &&&
zenith view
forward view
permanent structure (gray) occasional obstruc9on by solar panels (purple shade)
Changes from present “MAXI” • Instantaneous sky coverage 2% è 10%
– More short (<92 min), rare events • Slit-Slat è Coded mask
– More (×10) photons from short events – Better localization for short/variable events
• Proportional counterèCCD – Much simpler calibration for photon positions – Improved spectral resolution 1.2 keV à0.15 keV – Lower energy threshold 2 keV à0.7 keV
25
2014 2015 2016 2017 2018 2019
SLC�（Soft X-‐‑‒ray�Large S�y�Camera）�
HXM （Hard X-ray
Monitor）
Cryogenics
CCD package
Cryogenics tests camera body
fab
PM Camera +mask
+electronics integrated test
FM detailed
design
Prototype Flight Model
PM fab/test
Coded mask design
coded mask fabrication/test
detailed design
iWF-MAXI preliminary
design
electronics design/test
sensor design
fabrication
test
iWF-MAXI Development Schedule
��s�����
Integration tests
mission ops
software dev
ground cal.
science software develop.
AO selection
Other flight opportunities
flight operation
Conclusion • Soft X-ray transients:
– Not fully explored yet (unlike in hard X-ray) – Suggestive events observed by MAXI and HETE-2 – Theoretical expectations for GW
• iWide-Field MAXI – large sky coverage to capture prompt emission
from GW events – rapid development/deployment for adv. LIGO/Virgo/
KAGRA era – Proposal (down-scaled) under review
27
