James E. Larkin

Design and development of NIRSPEC: a near-infrared echelle spectrograph for the Keck II telescope

The design and development of NIRSPEC, a near-IR echelle spectrograph for the Keck II 10-meter telescope is described. This instrument is a large, facility-class vacuum-cryogenic spectrometer with a resolving power of R equals 25,000 for a 0.4 inch slit. It employs diamond-machined metal optics and state-of-the-art IR array detectors for high throughput, together with powerful user-friendly software for ease of use.

THE KILOPARSEC-SCALE KINEMATICS OF HIGH-REDSHIFT STAR-FORMING GALAXIES

We present the results of a spectroscopic survey of the kinematic structure of star-forming galaxies at redshift z ∼ 2–3 using Keck/OSIRIS integral field spectroscopy. Our sample is comprised of 12 galaxies between redshifts z ∼ 2.0 and 2.5 and one galaxy at z ∼ 3.3 which are well detected in either Hα or [O iii] emission. These galaxies are generally representative of the mean stellar mass of star-forming galaxies at similar redshifts, although they tend to have star formation rate surface densities slightly higher than the mean. These observations were obtained in conjunction with the Keck laser guide star adaptive optics system, with a typical angular resolution after spatial smoothing ∼0. 15 (approximately 1 kpc at the redshift of the target sample). At most five of these 13 galaxies have spatially resolved velocity gradients consistent with rotation while the remaining galaxies have relatively featureless or irregular velocity fields. All of our galaxies show local velocity dispersions ∼60–100 km s −1 , suggesting that (particularly for those galaxies with featureless velocity fields) rotation about a preferred axis may not be the dominant mechanism of physical support. While some galaxies show evidence for major mergers such evidence is unrelated to the kinematics of individual components (one of our strongest merger candidates also exhibits unambiguous rotational structure), refuting a simple bimodal disk/merger classification scheme. We discuss these data in light of complementary surveys and extant UV-IR spectroscopy and photometry, concluding that the dynamical importance of cold gas may be the primary factor governing the observed kinematics of z ∼ 2 galaxies. We conclude by speculating on the importance of mechanisms for accreting low angular momentum gas and the early formation of quasi-spheroidal systems in the young universe.

DETECTION AND CHARACTERIZATION OF EXOPLANETS AND DISKS USING PROJECTIONS ON KARHUNEN-LOÈVE EIGENIMAGES

We describe a new method to achieve point-spread function (PSF) subtractions for high-contrast imaging using principal component analysis that is applicable to both point sources or extended objects (disks). Assuming a library of reference PSFs, a Karhunen–Lo` eve transform of these references is used to create an orthogonal basis of eigenimages on which the science target is projected. For detection this approach provides comparable suppression to the Locally Optimized Combination of Images (LOCI) algorithm, albeit with increased robustness to the algorithm parameters and speed enhancement. For characterization of detected sources, the method enables forward modeling of astrophysical sources. This alleviates the biases in the astrometry and photometry of discovered faint sources, which are usually associated with LOCI-based PSF subtractions schemes. We illustrate the algorithm performance using archival Hubble Space Telescope images, but the approach may also be considered for ground-based data acquired with angular differential imaging or integral-field spectrographs.

First light of the Gemini Planet Imager

Bruce Macintosh a , James R. Graham , Patrick Ingraham b , Quinn Konopacky , Christian Marois , Marshall Perrin f , Lisa Poyneer a , Brian Bauman a , Travis Barman , Adam Burrows , Andrew Cardwell , Jeffrey Chilcote j , Robert J. De Rosa , Daren Dillon , Rene Doyon , Jennifer Dunn e , Darren Erikson e , Michael Fitzgerald j , Donald Gavel l , Stephen Goodsell i , Markus Hartung i , Pascale Hibon i , Paul G. Kalas c , James Larkin j , Jerome Maire d , Franck Marchis , Mark Marley , James McBride c , Max Millar-Blanchaer d , Katie Morzinski , Andew Norton l B. R. Oppenheimer , Dave Palmer a , Jennifer Patience k , Laurent Pueyo f , Fredrik Rantakyro i , Naru Sadakuni i , Leslie Saddlemyer e , Dmitry Savransky , Andrew Serio i , Remi Soummer f Anand Sivaramakrishnan f , q Inseok Song , Sandrine Thomas , J. Kent Wallace , Sloane Wiktorowicz l , and Schuyler Wolff vSignificance Direct detection—spatially resolving the light of a planet from the light of its parent star—is an important technique for characterizing exoplanets. It allows observations of giant exoplanets in locations like those in our solar system, inaccessible by other methods. The Gemini Planet Imager (GPI) is a new instrument for the Gemini South telescope. Designed and optimized only for high-contrast imaging, it incorporates advanced adaptive optics, diffraction control, a near-infrared spectrograph, and an imaging polarimeter. During first-light scientific observations in November 2013, GPI achieved contrast performance that is an order of magnitude better than conventional adaptive optics imagers. The Gemini Planet Imager is a dedicated facility for directly imaging and spectroscopically characterizing extrasolar planets. It combines a very high-order adaptive optics system, a diffraction-suppressing coronagraph, and an integral field spectrograph with low spectral resolution but high spatial resolution. Every aspect of the Gemini Planet Imager has been tuned for maximum sensitivity to faint planets near bright stars. During first-light observations, we achieved an estimated H band Strehl ratio of 0.89 and a 5-σ contrast of 106 at 0.75 arcseconds and 105 at 0.35 arcseconds. Observations of Beta Pictoris clearly detect the planet, Beta Pictoris b, in a single 60-s exposure with minimal postprocessing. Beta Pictoris b is observed at a separation of 434 ± 6 milliarcseconds (mas) and position angle 211.8 ± 0.5°. Fitting the Keplerian orbit of Beta Pic b using the new position together with previous astrometry gives a factor of 3 improvement in most parameters over previous solutions. The planet orbits at a semimajor axis of 9.0−0.4+0.8 AU near the 3:2 resonance with the previously known 6-AU asteroidal belt and is aligned with the inner warped disk. The observations give a 4% probability of a transit of the planet in late 2017.

The Gemini Planet Imager: From Science to Design to Construction

The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. It combines a 1500 subaperture AO system using a MEMS deformable mirror, an apodized-pupil Lyot coronagraph, a high-accuracy IR interferometer calibration system, and a near-infrared integral field spectrograph to allow detection and characterization of self-luminous extrasolar planets at planet/star contrast ratios of 10-7. I will discuss the evolution from science requirements through modeling to the final detailed design, provide an overview of the subsystems and show models of the instruments predicted performance.

Discovery and spectroscopy of the young jovian planet 51 Eri b with the Gemini Planet Imager

An exoplanet extracted from the bright Direct imaging of Jupiter-like exoplanets around young stars provides a glimpse into how our solar system formed. The brightness of young stars requires the use of next-generation devices such as the Gemini Planet Imager (GPI). Using the GPI, Macintosh et al. discovered a Jupiter-like planet orbiting a young star, 51 Eridani (see the Perspective by Mawet). The planet, 51 Eri b, has a methane signature and is probably the smallest exoplanet that has been directly imaged. These findings open the door to understanding solar system origins and herald the dawn of a new era in next-generation planetary imaging. Science, this issue p. 64; see also p. 39 The Gemini Planet Imager detects a Jupiter-like exoplanet orbiting the young star 51 Eridani. [Also see Perspective by Mawet] Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric compositions and luminosities, which are influenced by their formation mechanisms. Using the Gemini Planet Imager, we discovered a planet orbiting the ~20-million-year-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water-vapor absorption. Modeling of the spectra and photometry yields a luminosity (normalized by the luminosity of the Sun) of 1.6 to 4.0 × 10−6 and an effective temperature of 600 to 750 kelvin. For this age and luminosity, “hot-start” formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the “cold-start” core-accretion process that may have formed Jupiter.

TESTS OF THE ACCELERATING UNIVERSE WITH NEAR-INFRARED OBSERVATIONS OF A HIGH-REDSHIFT TYPE Ia SUPERNOVA

We have measured the rest-frame B-, V -, and I-band light curves of a high-redshift type Ia supernova (SN Ia), SN 1999Q (z \ 0.46), using the Hubble Space Telescope (HST ) and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, a sensitive indicator of E B~I , interstellar or intergalactic dust, which could aUect recent cosmological measurements from high-redshift SNe Ia. Our observations disfavor a 30% opacity of SN Ia visual light by dust as an alternative to an accelerating universe. This statement applies to both Galactic-type dust (rejected at the 3.4 p con—dence level) and grayer dust (grain size ( 0.1 km, rejected at the 2.3¨2.6 p con—dence level) as proposed by Aguirre. The rest-frame I-band light curve shows the secondary maximum 1 month after the B maximum typical of nearby SNe Ia of normal luminosity, providing no indication of evolution as a func- tion of redshift out to z B 0.5. An expanded set of similar observations could improve the constraints on any contribution of extragalactic dust to the dimming of high-redshift SNe Ia. Subject headings: cosmology: observationsdistance scalesupernovae: general

Deep galaxy counts in the K band with the Kech telescope

We present deep galaxy counts in the K (⋋ 2.2 micrometer) band, obtained at the W. M. Keck 10 m telescope. The data reach limiting magnitudes K approximately 24 mag, about 5 times deeper than the deepest published K-band images to date. The counts are performed in three small (approximately 1 min), widely separated high-latitude fields. Extensive Monte Carlo tests were used to derive the completeness corrections and minimize photometric biases. The counts continue to rise, with no sign of a turnover, down to the limits of our data, with the logarithmic slope of d log N/dm = 0.315 +/- 0.02 between K = 20 and 24 mag. This implies a cumulative surface density of approximately 5 x 10^5 galaxies/sq deg, or approximately 2 x 10^10 over the entire sky, down to K = 24 mag. Our counts are in good agreement with, although slightly lower than, those from the Hawaii Deep Survey by Cowie and collaborators; the discrepancies may be due to the small differences in the aperture corrections. We compare our counts with some of the available theoretical predictions. The data do not require models with a high value of Omega_0, but can be well fitted by models with no (or little) evolution, and cosmologies with a low value of Omega_0. Given the uncertainties in the models, it may be premature to put useful constrains on the value of Omega_0 from the counts alone. Optical-to-IR colors are computed, using CCD data obtaind previously at Palomar. We find a few red galaxies with (r-K) approximately greater than 5 mag, or (i-K) approximately greater than 5 mag; these may be ellipticals at z approximately 1. While the redshift distribution of galaxies in our counts is still unknown, the flux limits reached would allow us to detect unobscured L_* galaxies out to substantial redshifts (z greater than 3?)

The Rest-Frame Optical Spectrum of MS 1512–cB58*

Moderate-resolution, near-IR spectroscopy of MS 1512-cB58 is presented, obtained during commissioning of the near-infrared spectrometer (NIRSPEC) on the Keck II telescope. The strong lensing of this z=2.72 galaxy by the foreground cluster MS 1512+36 makes it the best candidate for detailed study of the rest-frame optical properties of Lyman-break galaxies. In 80 minutes of on-source integration, we have detected Halpha, [N ii] lambdalambda6583, 6548, [O i] lambda6300, He i lambda5876, [O iii] lambdalambda5007, 4959, Hbeta, Hgamma, [O ii] lambda3727, and a strong continuum signal in the range of 1.29-2.46 µm. A redshift of z=2.7290+/-0.0007 is inferred from the emission lines, in contrast to the z=2.7233 calculated from UV observations of interstellar absorption lines. Using the Balmer line ratios, we find an extinction of E(B-V) = 0.27. Using the line strengths, we infer a star formation rate (SFR) of 620+/-18 M middle dot in circle yr-1 (H0=75, q0=0.1, and Lambda=0), which is a factor of 2 higher than that measured from narrowband imaging observations of the galaxy but is a factor of almost 4 lower than the SFR inferred from the UV continuum luminosity. The width of the Balmer lines yields a mass of Mvir=1.2x1010 M middle dot in circle. We find that the oxygen abundance is 13 solar, in good agreement with other estimates of the metallicity. However, we infer a high nitrogen abundance, which may argue for the presence of an older stellar population.

A Survey of Organic Volatile Species in Comet C/1999 H1 (Lee) Using NIRSPEC at the Keck Observatory

The organic volatile composition of the long-period comet C/1999 H1 (Lee) was investigated using the —rst of a new generation of cross-dispersed cryogenic infrared spectrometers (NIRSPEC, at the Keck Observatory atop Mauna Kea, HI). On 1999 August 19¨21 the organics spectral region (2.9¨3.7 km) was completely sampled at both moderate and high dispersion, along with the CO fundamental region (near 4.67 km), revealing emission from water, carbon monoxide, methanol, methane, ethane, acetylene, and hydrogen cyanide. Many new multiplets from OH in the 1¨0 band were seen in prompt emission, and numerous new spectral lines were detected. Several spectral extracts are shown, and global production rates are presented for seven parent volatiles. Carbon monoxide is strongly depleted in comet Lee relative to comets Hyakutake and Hale-Bopp, demonstrating that chemical diversity occurred in the giant