A Cryogenic Telescope for Far-Infrared Astrophysics: A Vision for NASA in the 2020 Decade A white paper submitted to NASA’s Cosmic Origins Program Office 1,2 1 4 2,3 3,1 2 C.M. Bradford ∗ , P.F. Goldsmith , A. Bolatto , L. Armus , J. Bauer , P. Appleton , A. Cooray5,2, C. Casey5, D. Dale6, B. Uzgil7,2, J. Aguirre7, J.D. Smith8, K. Sheth10, E.J. Murphy3, C. McKenney1,2, W. Holmes1, M. Rizzo9, E. Bergin11 and G. Stacey12 1Jet Propulsion Laboratory 2California Institute of Technology 3Infrared Processing and Analysis Center, Caltech 4University of Maryland 5University of California, Irvine 6University of Wyoming 7University of Pennsylvania 8University of Toledo 9Goddard Space Flight Center 10NRAO, Charlottesville 11University of Michigan 12Cornell University May 7, 2015 Abstract Many of the transformative processes in the Universe have taken place in regions obscured by dust, and are best studied with far-IR spectroscopy. We present the Cryogenic-Aperture Large Infrared-Submillimeter Telescope Observatory (CALISTO), a 5-meter class, space-borne telescope actively cooled to T 4 K, emphasizing moderate-resolution spec- ∼ troscopy in the crucial 35 to 600 µm band. CALISTO will enable NASA and the world to study the rise of heavy elements in the Universe’s first billion years, chart star formation and black hole growth in dust-obscured galaxies through cosmic time, and conduct a census of forming planetary systems in our region of the Galaxy. CALISTO will capitalize on rapid progress in both format and sensitivity of far-IR detectors. Arrays with a total count of a few arXiv:1505.05551v1 [astro-ph.IM] 20 May 2015 105 detector pixels will form the heart of a suite of imaging spectrometers in which each detector reaches the photon × background limit. The Far-IR Science Interest Group will meet from 3–5 June 20151 with the intention of reaching consensus on the architecture for the Far-IR Surveyor mission. This white paper describes one of the architectures to be considered by the community. One or more companion papers will describe alternative architectures. ∗[email protected] 1http://conference.ipac.caltech.edu/firsurveyor/ 1 P1: FUI September 30, 2000 16:14 Annual Reviews AR108-18 AA52CH10-Madau ARI 4 August 2014 10:30 768 GENZEL ψ CESARSKY abLookback time (Gyr) Lookback time (Gyr) 0 2 4 6 8 10 12 0 2 4 6 8 10 12 2.5 –0.8 IR ) 2 –3 –1.2 Mpc 〉 d –1 1.5 k ψ –1.6 2.5 log (M year 1 ψ –2 UV log 0.5 –2.4 Far-IR range at z=2.5 Far-IR range at z=6 0 012345678 0123456710 100 8 Redshift Rest Wavelength [Redshiftµm] Figure 1: LEFT Cosmic star formation rate history as measured in the rest-frame ultraviolet, and far-infrared, reprinted Figure 8 from Madau & Dickinson, 2014 [44]. Red points are from Spitzer and Herschel, green and blue from rest-frame UV (a) SFR densities in the FUV (uncorrected for dust attenuation)Figure and 3 in theCombined FIR. The data LWS pointsSWS with symbols spectra are given of galaxies in Table 1(>.All6 octaves). Left: Combined SWS/LWS surveys. Purple points are from the Bouwens et al. [7, 6] based on deep Hubble+ fields using dropout28 selections. UV and IR luminosities have been converted to instantaneousspectrum SFR densities of the using Circinus the factors galaxyFUV 1. (Moorwood15 10〉 and 1999,IR 4.5 Sturm et al 1999b). The H2 lines and 44Right: Full-band spectrum of Circinus, a nearby galaxy with an active nucleus obscuredK = by dust,ψ obtainedK with= the ψ 10〉 (cgs units) valid for a Salpeter IMF. (b)Meandustattenuationinmagnitudesasafunctionofredshift.Mostofthedatapointslow-excitation atomic/ionic fine structure lines ([FeII], [SiII], [OI], [CII]) sample photodissocia- shownInfrared are based Space on UV Observatory spectral slopes (ISO) or [25,stellar 50, population 63]. This model shows fitting. the range The symbol of ionized, shapes atomic, and colors and correspond molecular to gas the cooling data sets 4 12 2 lines originating deep in the obscured core of thetion source. regions (Vertical (PDRs axis is λF; Sternbergλ, major ticks & 5 Dalgarno10− W m1995,− .) Hollenbach & Tielens 1997), shocks (Draine et cited in Table 1,withtheadditionofSalimetal.(2007)(cyan pentagon). Two versions of the attenuation× factors are shown for UV-selected galaxies at 2 < z < 7 (Reddy & Steidel 2009,al Bouwens 1983, etHollenbach al. 2012a) (offset & McKeeslightly in 1989), the redshift or axisX-ray for clarity): excited one gas (Maloney et al 1996). Hydrogen recom- integrated1Introduction, over the observed population Motivation (open symbols), the other extrapolated down to L 0(filled symbols). Data points from FUV = Burgarella et al. (2013) (olive green dots) are calculated by comparingbination the lines integrated and low-lying FIR and FUV ionic luminosity fine structure densities in linesredshift (excitation bins, potential <50 eV: [ArIII], [NeII], ratherAfter thanthe from Cosmic the UV Microwave slopes or UV-optical Background spectral (CMB) energy[NeIII], is distributions. accounted [SIII], for, Abbreviations: [OIII], the remaining [NII]) FIR,cosmic sample far-infrared; background mainly FUV, far-UV; HII light regions is IMF, the photoionized by OB stars (Spinoglio & initialintegrated mass function; emission IR, infrared; from all SFR, stars star-formation and galaxies rate.throughMalkan cosmic 1992, time. Voit The 1992), spectrum although of this cosmic ionizing background shocks shows may contribute in some sources (e.g. Contini two broad peaks with comparable observed flux density, one at 1 µm, and one at 150 µm. The long-wavelength ∼ ∼ component, called the Cosmic Infrared Background&Viegas (CIB) [23, 1992, 19], is Sutherland radiation from et dust al heated 1993). by Ionic stars or lines accreting from species with excitation potentials up to black holes. Its prominencesamples. is The a simple local consequence FIRLF has300 not of theeV been fundamental (e.g. drastically [OIV], link revised [NeV], between since the[NeVI], the star final formation IRAS [SiIX]) analyses and probe its fuel:(Sanders highly ionized coronal gas and require very the interstellar gas withet al. obscuring 2003, Takeuchi dust. We et now al. 2003);hardψ have strong radiation additional evidence AKARI fields that most (suchdata didof asthe notthe energy drastically accretion that has change been disks earlier produced of resultsAGNs) or fast ionizing shocks. Line ratios by galaxies through cosmic(Goto et time al. has 2011a,b; emerged Sedgwick in the far-IR et al. [54, 2011). 44]. The The typicalbiggest UV/optical remaining photon uncertainties from a young pertain star to the has been absorbed byfaint-end dust and re-radiated slope, where (see measurements Figuregive 1).In information general, vary significantly rest-frame about theultraviolet from physicalψ and optical-wavelength1 characteristics.2to 1.8 (or, somewhat oflight the emitting gas. Extinction corrections are = 〉 〉 does not access the obscuredimplausibly, regions even that2.0) dominate (e.g.,small Gotothe activity(A( etψ al.)/ in 2011b).A(V) galaxies. Analysis0.1 Similarly, to of 0.01 the in in widest-areanearby the 2–40galaxies FIRµ andm surveys region). in our fromRight: The starburst galaxy M82 (top): 〉 ψ own Milky Way, star-formingHerschel, such cores, as embedded H-ATLAS younglow (570 excitation stars, deg2) and (Eales protoplanetary lines, et al. strong 2010), disks may UIBs/PAHs; all help cool with primarily this. and The through the present AGN the un- NGC 1068 (bottom): high excitation, no far-infrared. certainties lead to a differenceUIBs/PAHs of a factor (Sturm of at least et 2 al to 1999b, 3 in the Colbert local FIR et luminosity al 1999, density. Spinoglio et al 1999). Sudden breaks in the Access provided by NASA Jet Propulsion Laboratory on 04/06/15. For personal use only. The spaceborne Spitzer and Herschel observatories have demonstrated the importance of the far-IR waveband, but Annu. Rev. Astro. Astrophys. 2014.52:415-486. Downloaded from www.annualreviews.org Nevertheless, as previously noted, in today’s relatively “dead” epoch of cosmic star formation, a it is only with sensitive spectroscopic capability thatSEDs astronomers are the will result have of the different opportunity aperture to study sizes in detail at the different inner wavelengths. Local bumps and unusual significant fraction of the FIR emission from ordinary spiral galaxies may arise from dust heated workings of galaxies at cosmological distancesby NASA Jet Propulsion Laboratory on 03/18/09. For personal use only. andslopes late-stage in the forming Circinus planetary spectrum systems. (12–20 This capabilityµm and has not 35 yetµm) may be caused by residual calibration by intermediate-age and older stellar populations, not newly formed OB stars. Hence, it is not been realized because it requires a combination ofuncertainties. a cold telescope and very sensitive direct detectors. After 2 decades of development of superconductingnecessarily the detectors,best measure and ofwith the the SFR. system-level At higher experience redshifts, gained when the with cosmic-specific previous-generation SFR was cryogenic satellites,much we are larger, now in new a position star formation to field should CALISTO, dominate a large dust space heating, telescope making actively the IRcooled emission to a few a more degrees K with 10robust5 individual global far-IR tracer. detector pixels, each operating at the fundamental sensitivity limit set by the ∼ Annu. Rev. Astro. Astrophys. 2000.38:761-814. Downloaded from arjournals.annualreviews.org astrophysical background.Local This measurements paper builds on of the the concept SMDexcitation/ionization have for CALISTO relied mainly presented on purely late states last optical decade and data are [26, (e.g., 10]; characteristic SDSS it will pho- tracers of different physical re- be a large facility-classtometry observatory and spectroscopy) launched to an or earth-sun on relativelygions: L2 halo shallowphotodissociation orbitwith NIR at data least from a 5-yearregions 2MASS.