The Keck Low-Resolution Imaging Spectrometer

Oke, J. B.; Cohen, Jason Blake; Carr, M.; Cromer, John; Dingizian, A.; Harris, Frederick H.; Labrecque, Sandra; Lucinio, R.; Schaal, W.; Epps, Harland W.; Miller, J. M.

doi:10.1086/133562

Cited by 1,944 publications

(1,761 citation statements)

References 6 publications

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“…Chapman et al describe a population of 850µm-selected SMGs which have radio counterparts; these radio counterparts have astrometric precision <1 and provide excellent multi-slit spectroscopic targets. The Chapman et al sample of 73 galaxies was spectroscopically observed at Keck Observatory using the LRIS instrument (Oke et al, 1995) and has a median redshift of z = 2.2 (some of these redshifts had been reported in earlier works, e.g. Barger et al, 2000;Chapman et al, 2003b).…”

Section: Redshift Distributions Of 850µm-14 Mm-selected Dsfg Populatmentioning

confidence: 95%

Dusty star-forming galaxies at high redshift

2014

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Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10 13 L with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrared instrumentation in recent years, both spacebased and ground-based, has led to the detection of nearly a million DSFGs, yet our understanding of the underlying astrophysics that govern the start and end of the dusty starburst phase is still in nascent stage. This review is aimed at summarizing the current status of DSFG studies, focusing especially on the detailed characterization of the bestunderstood subset (submillimeter galaxies, who were summarized in the last review of this field over a decade ago, Blain et al. 2002), but also the selection and characterization of more recently discovered DSFG populations. We review DSFG population statistics, their physical properties including dust, gas and stellar contents, their environments, and current theoretical models related to the formation and evolution of these galaxies.

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Section: Redshift Distributions Of 850µm-14 Mm-selected Dsfg Populatmentioning

confidence: 95%

Dusty star-forming galaxies at high redshift

2014

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“…Palomar observations utilized the dualbeam Double Spectrograph on the 200-inch Hale Telescope, which was configured with the 1.5 arcsec wide slit, the 5500 Å dichroic, the 600 mm −1 grating on the blue arm (λ blaze = 4000 Å; spectral resolving power R ≡ λ/ λ ∼ 1200), and the 316 mm −1 grating on the red arm (λ blaze = 7500 Å; R ∼ 1800). Keck observations utilized the dual-beam Low Resolution Imaging Spectrograph (LRIS; Oke et al 1995) on the Keck I telescope, configured with the 1.5 arcsec wide slit, the 600 mm −1 grism on the blue arm (λ blaze = 4000 Å; R ∼ 800) and the 400 mm −1 grating on the red arm (λ blaze = 8500 Å; R ∼ 1000). All nights listed in Table A1 were photometric, and we processed the data using standard techniques within IRAF.…”

Section: A P P E N D I X a : S P E C T Ro S C O P I C O B S E Rvat I mentioning

confidence: 99%

Understanding extreme quasar optical variability with CRTS – I. Major AGN flares

Graham¹,

Djorgovski²,

Drake³

et al. 2017

Monthly Notices of the Royal Astronomical Society

119

133

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There is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present the results of a systematic search for major flares in active galactic nucleus (AGN) in the Catalina Real-time Transient Survey as part of a broader study into extreme quasar variability. Such flares are defined in a quantitative manner as being atop of the normal, stochastic variability of quasars. We have identified 51 events from over 900 000 known quasars and high-probability quasar candidates, typically lasting 900 d and with a median peak amplitude of m = 1.25 mag. Characterizing the flare profile with a Weibull distribution, we find that nine of the sources are well described by a single-point single-lens model. This supports the proposal by Lawrence et al. that microlensing is a plausible physical mechanism for extreme variability. However, we attribute the majority of our events to explosive stellar-related activity in the accretion disc: superluminous supernovae, tidal disruption events and mergers of stellar mass black holes.

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“…In preparation for, and in support of, the NuSTAR observations, we also obtained optical spectroscopy of NGC 7674 using the Low Resolution Imaging Spectrometer (LRIS) on the Keck Telescope (Oke et al 1995). The observations were carried out on 2014 June 25 through a 1.0 arcsec wide slit, using both the blue (600 lines mm −1 ) grism and the red (400 lines mm −1 ) grating, with the D560 dichroic.…”

Section: Optical Spectroscopymentioning

confidence: 99%

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

Gandhi

Annuar

Lansbury

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe XXVI ionised line (EW ≈ 0.2 keV). We construct an updated longterm X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past ≈ 20 years, following a high flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be ∼ 3.2 pc under the switchedoff AGN scenario, ≈ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (N H ) of 3 × 10 24 cm −2 at present, and yields an intrinsic 2-10 keV luminosity of (3-5) × 10 43 erg s −1 . Realistic uncertainties span the range of ≈ (1-13) × 10 43 erg s −1 . The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionised Fe emission. It exemplifies the difficulty of identification and proper characterisation of distant CTAGN based on the strength of the neutral Fe Kα line.

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The Keck Low-Resolution Imaging Spectrometer

Cited by 1,944 publications

References 6 publications

Dusty star-forming galaxies at high redshift

Dusty star-forming galaxies at high redshift

Understanding extreme quasar optical variability with CRTS – I. Major AGN flares

The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

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