LiteBIRD A Small Satellite for the Studies of B-mode Polarization and Inflation from Cosmic Background Radiation Detection Masashi Hazumi Institute of Particle and Nuclear Studies High Energy Research Accelerator Organization (KEK) Tsukuba, Japan On behalf of the LiteBIRD working group [1] I am going to talk about LiteBIRD, which is a small satellite for the studies of B-mode polarization and inflation from cosmic background radiation detection. 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD project overview
Scientific goal Stringent tests of cosmic inflation at the extremely early universe Observations Full-sky CMB (i.e. mm wave) polarization survey at a degree scale Strategy Roadmap includes ground-based projects as important steps Focus on signals of inflationary gravitationalwaves imprinted in CMB polarization Synergy with ground-based super-telescopes Project status/plans Working group authorized by SCSS, supported by JAXA Mission definition review in 2013, target launch year ~2020 CMB : Cosmic Microwave Background [6] The scientific goal of LiteBIRD is to make stringent tests of cosmic inflation, the leading hypothesis at the extremely early universe. To this end, we need to carry out a full-sky CMB polarization survey at a degree scale. As for our strategy, our roadmap includes ground-based projects as important steps, which I explain in the next slide. We focus on signals of inflationary gravitational waves imprinted in CMB polarization. At the same time, we plan to have a strong ground-based super-telescope program accompanied, so that the synergy between space and ground-based measurements gives a wide range of scientific outputs as a whole in a very cost-effective manner. The LiteBIRD working group was authorized by Japanese steering committee for space science and is supported by JAXA. Studies toward the mission definition review are in progress, with a target launch year around 2020. 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD roadmap POLARBEAR-2 LiteBIRD POLARBEAR GroundBIRD
[3] The LiteBIRD roadmap includes ground-based projects, POLARBEAR, POLARBEAR-2 and GroundBIRD, as important steps. These are useful for verification of key technologies, yet they themselves are designed to produce good scientific results. Ground-based projects as important steps Verification of key technologies Good scientific results International projects 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD working group
58 members (as of Aug.15, 2012) International and interdisciplinary KEK Y. Chinone K. Hattori M. Hazumi (PI) M. Hasegawa K. Ishidoshiro* N. Kimura T. Matsumura H. Morii M. Nagai** R. Nagata N. Sato T. Suzuki O. Tajima T. Tomaru M. Yoshida ISAS/JAXA H. Fuke H. Matsuhara K. Mitsuda S. Sakai Y. Takei N. Yamazaki T. Yoshida UC Berkeley A. Ghribi W. Holzapfel A. Lee (US-PI) H. Nishino P. Richards A. Suzuki UT Austin E. Komatsu ATC/NAOJ K. Karatsu T. Noguchi Y. Sekimoto Y. Uzawa RIKEN K. Koga C. Otani IPMU N. Katayama Tohoku U. M. Hattori Yokohama NU. S. Murayama S. Nakamura K. Natsume Y. Takagi Kinki U. I. Ohta + Korea U. under consideration McGill U. M. Dobbs ARD/JAXA I. Kawano A. Noda Y. Sato K. Shinozaki H. Sugita K. Yotsumoto CMB experimenters (Berkeley, KEK, McGill, Eiichiro) LBNL J. Borrill X-ray astrophysicists (JAXA) Okayama U. H. Ishino A. Kibayashi S. Mima Y. Mibe Tsukuba U. S. Takada [2] There are more than 50 members in the working group, including CMB experimenters, X-ray astrophysicists, infrared astronomers, JAXA engineers and superconducting device developers. It is international and interdisciplinary. Infrared astronomers (JAXA) SOKENDAI Y. Inoue A. Shimizu H. Watanabe Superconducting Device (Berkeley, RIKEN, NAOJ, Okayama, KEK etc.) JAXA engineers and Mission Design Support Group 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD mission Check representative inflationary models
requirement on the uncertainty on r stat. syst. foreground lensing) dr < 0.001 No lose theorem of LiteBIRD Many inflationary models predict r>0.01 >10sigma discovery Representative inflationary models (single-large-field slow-roll models) have a lower bound on r, r>0.002, from Lyth relation. no gravitational wave detection at LiteBIRD exclude representative inflationary models (i.e. 95% C.L.) Early indication from ground-based projects power spectra at LiteBIRD ! [1+3] Now I come to the mission of LiteBIRD. The mission is to check representative inflationary models. period. To be more specific, we require that the total uncertainty on r be less than 0.001, where the uncertainty includes those from statistical and systematic errors, as well as from foregrounds and lensing. This requirement leads to a kind of no lose theorem of LiteBIRD. I tell you why. Many inflationary models predict r greater than If that is the case, we expect a discovery with more than 10 sigmas with LiteBIRD. Furthermore, it is known that representative inflationary models have a lower bound on r, r greater than 0.002, from Lyth relation. Therefore, if there is no gravitational wave detection at LiteBIRD, we exclude all the representative inflationary models with 95% C.L.which gives a severe constraint on cosmology. Last of all, in case some indication of the signal is obtained from ground-based projects, that means r is fairly large, large enough that LiteBIRD can measure the B-mode power spectrum, which gives much more information in identifying the correct model of inflation. So, LiteBIRD will give a huge impact on cosmology in any case. Huge impact on cosmology in any case 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD system overview Spin axis Bore sight 2ndary HWP mirror (4K)
Super- conducting Focal plane (100mK) Primary mirror (4K) Cryocoolers (ST/JT + ADR) [1+2] Here is an overview of the LiteBIRD system. From the sky side to the detector side, key components are rotating HWP, the primary mirror, the secondary mirror, and the super-conducting focal plane. With the cryocooler system, mirrors are cooled down to 4K, and the bath temperature for the focal plane is 100mK. Solar panels Standard bus system for JAXAs small satellites 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) Three key technologies to make LiteBIRD light
Prototype crossed Mizuguchi-Dragone mirror Small mirrors (~60cm) Warm launch with mechanical coolers Technology alliance with SPICAfor pre-cooling (ST/JT) Alliance with DIOS (X-ray mission)for ADR Multi-chroic focal plane ~2000 TES (Tbath=100mK, dn/n ~ 0.3), or equivalent MKIDs Technology demonstration with ground-based projects (POLARBEAR, POLARBEAR-2, GroundBIRD) 2ST/JT BBM 100GHz 220GHz 150GHz Bolometers Sinuous antenna Fabricated Triplexer Filter {1+3} There are three key technologies to make LiteBIRD light. Small mirrors, warm launch with mechanical coolers, and the multi-chroic focal plane. The LiteBIRD cooling system is rather similar to SPICAs pre-cooling, and ADR is very similar to one of future X-ray missions DIOS., so we have a good technology alliance here. Multi-chroic focal plane is doable with about 2000 sensors, which is large but within a reach. UC Berkeley TESoption 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) Major system requirements
Item Requirements Remarks Orbit LEO (~500km) or L2 Launch vehicle: Epsilon or H2 Observing time > 2 years Weight < 450kg from Epsilon payload requirement Power < 500W from JAXAs standard bus system Total sensitivity < 3mKarcmin 2mKarcmin as the design goal Angular resolution < 30arcmin for 150GHz descoping requires justification Observing frequencies GHz (or wider) 4 bands Modulation/Demodulation HWP rotation > 1Hz HWP = Half Wave Plate 1/f knee (f) scan rate (R) R/f > 0.06 rpm/mHz (e.g.R>1.2rpm for f=20mHz) spec. for the case HWP stops Telemetry > 10GB/day w/ Planck-type data suppression Total systematic errors < 18nK2 on CBB (l=2) [1+1] Major system requirements are listed here. We are studying right now both LEO and L2 orbits, with JAXAs Epsilon or H2 rocket. The observing time is more than 2 years, Requirements on the weight and power are based on constraints from the Epsilon rockets payload and JAXAs standard bus system, which may be relaxed if you go for the H2 option. The total sensitivity should be better than 3microkelvin arcminute, the angular resolution should be better than 30arcmin for 150GHz, and observing frequencies should cover GHz with 4 or more bands. We plan to use continuously rotating HWP, but the minimal success should be achieved even if the HWP stops. For that purpose we have requirements on the 1/f knee frequency and scan rate. Our data are a little less than 10GB/day assuming Planck-type data suppression. So the requirement is to download more than 10GB/day. The total systematic error should be well below the lensing B-mode floor. Because of the limited time I cannot go into details of systematic error studies today. These requirements are still subject to modifications in the feasibility studies 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD scan strategy: LEO case
150 Mkm Sun Earth Satellite 0.38 Mkm Earth Moon = 76 degs = 34 degs x y z Spin axis Anti-sun Boresight altitude 500 km - Spin axis rotation about anti-sun axis (i.e. satellite period around the earth) fs = 90 min - Boresight axis rotation about spin axis fb ~ 0.6 rpm 6000K 300K 175K : relative angle betw/n moon and boresight (60 degs) scan uniformity cross link [3] Requirements for scan strategy include uniform density in the sky, wide daily coverage, and good crosslinkings. In both L2 and LEO, we are considering scan strategy with off-spin-axis boresight and spin axis rotation, as if the telescope were a spinning top undergoing a slow precession. Here I show the LEO case as an example, which has more constraints than the L2 case. It turns out that uniformity and cross link are nearly as good as those at L2. LEO 2012/08/15 Uniformity and cross link nearly as good as those at L2 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD optics 4K Reflective Optics HWP example Boresight 2ndary
Crossed Mizuguchi-Dragone 30cm 2ndary mirror HWP (f30cm) T. Matsumura, doctoral thesis super-conducting bearing wide-band AR (EBEX) Focal plane Primary mirror Mirror diameter ~60cm for ~0.5angular resolution is sufficient for both reionization and recombination bumps [1+2] This is a slide about LiteBIRD optics. We employ a compact crossed Mizuguchi-Dragone design with the mirror size of about 60cm for a half degree angular resolution, which is sufficient for both reionization and recombination bumps. With this design the diameter of HWP is 30cm. Prototype mirrors 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) Focal plane requirement
Noise level: goal = 2mKarcmin (requirement: < 3mKarcmin) To be well below lensing floor [2] The focal plane requirement, 3microkelvin-arcminutes, comes from the fact that the lensing B-mode behaves as the external noise unless you find a way to reduce the effect. Then if the noise level should be well below the lensing floor, that is enough. 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) Foreground removal and observing bands
Foreground removal 4 bands in GHz N. Katayama and E. Komatsu, ApJ 737, 78 (2011) (arXiv: ) pixel-based polarized foreground removal model-independent very small bias r~0.0006 with 60,100,240GHz (3 bands) [3] Foreground removal and observing bands were studied based on the template cleaning method and results were described in the paper listed here. They achieved a very small bias less than From the results, we require that our observations should have 4 or more bands in b/w 50 to 270. 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD band selection for multi-chroic pixels
We chose the band locations with the following reasons. Katayama-Komatsu (2010) suggested the range of frequency from GHz based on the template subtraction. We want to exclude the CO lines. From the practical consideration such as AR coating on a lenslet array, it is reasonable to limit the bandwidth to /~1. Above three constraints naturally put us to the band locations. CO J J J3-2 Large pixel (/=1) Small pixel (/=1) /=0.23 per band /=0.3 per band GHzGHz GHzGHz GHz GHz 50-320GHz 100GHz 220GHz 150GHz Bolometers Sinuous antenna Fabricated Triplexer Filter [2] We chose the band locations with 3 reasons. First of all, we take suggestions in the Katayama-Komatsu paper, which I already mentioned. Secondly, we also want to exclude the CO lines. Thirdly, from the practical consideration such as AR coating on a lenslet array, it is reasonable to limit the bandwidth to about 100% for each pixel. Then we naturally comes to the band selection shown here. Three bands with centers at 60,78 and 100 GHz for the low-frequency pixel, and another set of three bands at 143, 190 and 280 GHz, so that in total the focal plane covers from 50 to 320 GHz with 6 bands. UC Berkeley TESoption 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD focal plane design
tri-chroic140/190/280GHz UC Berkeley TESoption 2022 TES bolometers Tbath = 100mK tri-chroic60/78/100GHz 1.8mKarcmin (w/ 2 effective years) Strehl ratio>0.8 POLARBEAR focal plane as a prototype [4] An example implementation with UC Berkeleys multi-chroic TES technology is shown here. We need 2022 TES bolometers. All pixels are within an area of high Strehl ratio, and we achieve the total sensitivity of 1.8microkelvin-arcmin, which meets our requirement. 2ST/JT BBM 2012/08/15 Inflation Probe Science Analysis Group (IPSAG) Workshop, Washington DCMasashi Hazumi (KEK) LiteBIRD focal plane design
tri-chroic140/190/280GHz Band centers can be distributed to increase the effective number of bands UC Berkeley TESoption 2022 TES bolometers Tbath = 100mK tri-chroic60/78/100GHz Strehl ratio>0.8 POLARBEAR focal plane as a prototype More space to place