K(2 m) Version of JASMINE and its Science Advantage in Bulge Science and Potential By-products from Idle Time T. Nakajima (NAOJ)

Demand from Instrumentation Radiation cooling at L2 point sets telescope environmental temperature down to about 50K. Since the operating temperature of CCDs is about 150K, they must to warmed up!　　　　　　　　　　　 ----- Detectors are heat sources. The operating temperature of HgCdTe NIR arrays is about 70K. 　　　　 　Better matching with environmental temperature.

Abstract of K (2 m) Science Main advantage of JASMINE-K A. astrometric accuracy of Bulge stars with Av>6 is better compared with that at z band (0.9 m). B. Since, AZ ~ 4 AK , QSO/AGN count is much greater at K. They behave as fixed positional references. By-products More than 1 / 4 of the mission period should be used for other purposes such as NIR deep survey due to the Bulge-Sun coincidence. At high Galactic latitudes, the limit of galaxy count is set by confusion to K = 24 ~ 25. An example of science program: A search for QSOs beyond z = 7.

Main advantages for bulge stars Bulge Giants Intrinsic SEDs are red. Combining the SED and extinction, astrometric error given by σ~ /D/√N, is smaller at K than z for Av > 6. Background QSO count If we estimate the QSO number count in JASMINE field of 200 sq. deg from extinction-free high latitude QSO counts, a meaningful number of them are expected. Identification of these QSOs prior to the mission, and long-exposures of these QSO fields at the mission will necessary.

Relative astrometric accuracy of Bulge giants between z and K K is better if σz/σK>1.

Range of QSO count in 200 sq deg JASMINE field Assumptions: Av=0. fν~ ν-1 for QSOs. UV – excess selected quasars (large U-B, or u-g) PG quasars w/ correction n(K<11.8) < 3.4. LBQS n(K<14) ~ 200, n(K<13)~125, n(K<12) ~ 3. Fainter and more distant QSOs from SDSS Including narrow-line QSOs/AGNs n(K<13.8) > 4.0. (SDSS misses brightest ones.) Variability selection n(K<15.4) ~ 1000 (SDSS, σvar > 0.03 mag) n(K<16.3) > 400 (MACHO,LMC,+color)

Extragalactic astronomy during the idle time of Bulge observations How to utilize 1 / 4 of astrometry idle time? Taking advantage of a wide FOV (0.7x0.7deg). Advantage of NIR imaging from space. The zodiacal background has its minimum in NIR, since its a valley between scattered Sun light in the visible and thermal dust emission in MIR. Telescope thermal emission is negligible at L2. Re-ionization era (z=10~17) can be probed at rest-frame UV at K band.

Sensitivity at K (Point source) Age of Univ. rest (m) Lrest (Lsun)

K band (5 kpc extended source）

H (1.6) band (Point source）

H(1.6) band (5kpc extended source）

Sky at K (Vega) > 23 Cumulative galaxy count (Eg. Minowa et al. 2006) 1 galaxy in 10 square arcsec. (1 in 3”x3”) at K~23. Since galaxies are extended, better resolution (larger telescope) does not necessarily remedy the confusion problem. --- there may be more than one galaxy for each line of sight at K>25. In one quarter of the mission life of JASMINE, 5,000 ~ 10,000 sq. deg. will be surveyed.

Conceivable New Science Programs QSO/AGN survey up to z ~ 13 (H dropout). My empirical number count estimation in 10,000 sq. deg. 3 for M145 < -26 (1012 Lsun) between z=10 & 13. 6 for M145 < -25 (3x1011 Lsun) between z=10 & 13. Foreground ISM study or locating high density regions. Wide-filed galaxy count down to K=24 and/or Extragalactic NIR background radiation, if superposition of faint galaxies is inevitable.