Engineering topics

Rigby, Jane R.

Publications and source records attributed to Rigby, Jane R..

26 records · Page 2

NASA NTRS2012

Stellar Populations of Highly Magnified Lensed Galaxies: Young Starbursts at Z approximately 2

We present a comprehensive analysis of the rest-frame UV to near-IR spectral energy distributions (SEDs) and rest-frame optical spectra of four of the brightest gravitationally lensed galaxies in the literature: RCSGA 032727-132609 at z = 1.70, MS1512-cB58 at z = 2.73, SGAS J152745.1+065219 at z = 2.76, and SGAS J122651.3+215220 at z = 2.92. This includes new Spitzer imaging for RCSGA0327 as well as new spectra, near-IR imaging and Spitzer imaging for SGAS1527 and SGAS1226. Lensing magnifications of 3-4 mag allow a detailed study of the stellar populations and physical conditions. We compare star formation rates (SFRs) as measured from the SED fit, the Ha and [O II] ?3727 emission lines, and the UV+IR bolometric luminosity where 24 micron photometry is available. The SFR estimate from the SED fit is consistently higher than the other indicators, which suggests that the Calzetti dust extinction law used in the SED fitting is too flat for young star-forming galaxies at z ~ 2. Our analysis finds similar stellar population parameters for all four lensed galaxies: stellar masses (3-7) ? 10(exp 9)Solar M young ages approx 100 Myr, little dust content E(B - V) = 0.10-0.25, and SFRs around 20-100 solar M/ yr. Compared to typical values for the galaxy population at z approx. 2, this suggests we are looking at newly formed, starbursting systems that have only recently started the buildup of stellar mass. These results constitute the first detailed, uniform analysis of a sample of the growing number of strongly lensed galaxies known at z approx 2.

Wuyts, Eva↗

NASA NTRS2012

SGAS 143845.1 + 145407: A Big, Cool Starburst at Redshift 0.816

We present the discovery and a detailed multi-wavelength study of a strongly-lensed luminous infrared galaxy at z=0.816. Unlike most known lensed galaxies discovered at optical or near-infrared wavelengths, this lensed source is red, which the data presented here demonstrate is due to ongoing dusty star formation. The overall lensing magnification (a factor of 17) facilitates observations from the blue optical through to 500 micrometers, fully capturing both the stellar photospheric emission as well as the reprocessed thermal dust emission. We also present optical and near-IR spectroscopy. These extensive data show that this lensed galaxy is in many ways typical of IR-detected sources at z approximates 1, with both a total luminosity and size in accordance with other (albeit much less detailed) measurements in samples of galaxies observed in deep fields with the Spitzer telescope. Its far-infrared spectral energy distribution is well-fit by local templates that are an order of magnitude less luminous than the lensed galaxy; local templates of comparable luminosity are too hot to fit. Its size (D approximately 7 kpc) is much larger than local luminous infrared galaxies, but in line with sizes observed for such galaxies at z approximates 1. The star formation appears uniform across this spatial scale. Thus, this lensed galaxy, which appears representative of vigorously star-forming z approximates 1 galaxies, is forming stars in a fundamentally different mode than is seen at z approximates 0.

Gladders, Michael D.↗

NASA NTRS2011

Source Plane Reconstruction of the Bright Lensed Galaxy RCSGA 032727-132609

We present new HST/WFC3 imaging data of RCS2 032727-132609, a bright lensed galaxy at z=1.7 that is magnified and stretched by the lensing cluster RCS2 032727-132623. Using this new high-resolution imaging, we modify our previous lens model (which was based on ground-based data) to fully understand the lensing geometry, and use it to reconstruct the lensed galaxy in the source plane. This giant arc represents a unique opportunity to peer into 100-pc scale structures in a high redshift galaxy. This new source reconstruction will be crucial for a future analysis of the spatially-resolved rest-UV and rest-optical spectra of the brightest parts of the arc.

Sharon, Keren↗

NASA NTRS2011

Stellar Populations of Highly Magnified Lensed Galaxies Young Starburst at Z to Approximately 2

We present a comprehensive analysis of the rest-frame UV to near-IR spectral energy distributions and rest-frame optical spectra of four of the brightest gravitationally lensed galaxies in the literature: RCSGA 032727-132609 at z = 170, MS1512-cB58 at z = 2.73, SGAS J152745.1+065219 at z = 2.76 and SGAS J12265L3+215220 at z = 2.92. This includes new Spitzer imaging for RCSGA0327 as well as new spectra, near-IR imaging and Spitzer imaging for SGAS1527 and SGAS1226. Lensing magnifications of 3-4 magnitudes allow a detailed study of the stellar populations and physical conditions. We compare star formation rates as measured from the SED fit, the Ha and [O II] .(lambda)3727 emission lines, and the UV+IR bolometric luminosity where 24micron photometry is available. The SFR estimate from the SED fit is consistently higher than the other indicators, which suggests that the Calzetti dust extinction law used in the SED fitting is too flat for young star-forming galaxies at z approx. 2. Our analysis finds similar stellar population parameters for all four lensed galaxies: stellar masses 3 - 7 x 10(exp 9) Stellar mass, young ages approx. 100 Myr, little dust content E(B - V)=0.10-0.25, and star formation rates around 20- 100 Stellar mass/y. Compared to typical values for the galaxy population at z approx. 2, this suggests we are looking at newly formed, starbursting systems that have only recently started the build-up of stellar mass. These results constitute the first detailed, uniform analysis of a sample of the growing number of strongly lensed galaxies known at z approx. 2. Subject headings: galaxies: high-redshift, strong gravitational lensing, infrared: galaxies

Wuyts, Eva↗

NASA NTRS2011

Space Telescopes

The science of astronomy depends on modern-day temples called telescopes. Astronomers make pilgrimages to remote mountaintops where these large, intricate, precise machines gather light that rains down from the Universe. Bit, since Earth is a bright, turbulent planet, our finest telescopes are those that have been launched into the dark stillness of space. These space telescopes, named after heroes of astronomy (Hubble, Chandra, Spitzer, Herschel), are some of the best ideas our species has ever had. They show us, over 13 billion years of cosmic history, how galaxies and quasars evolve. They study planets orbiting other stars. They've helped us determine that 95% of the Universe is of unknown composition. In short, they tell us about our place in the Universe. The next step in this journey is the James Webb Space Telescope, being built by NASA, Europe, and Canada for a 2018 launch; Webb will reveal the first galaxies that ever formed.

Rigby, Jane R.↗

NASA NTRS2011

Status Update on the James Webb Space Telescope Project

The James Webb Space Telescope (JWST) is a large (6.6 m), cold (<50 K), infrared (IR)-optimized space observatory that will be launched in approx.2018. The observatory will have four instruments covering 0.6 to 28 micron, including a multi-object spectrograph, two integral fie ld units, and grisms optimized for exoplanets. I will review JWST's k ey science themes, as well as exciting new ideas from the recent JWST Frontiers Workshop. I will summarize the technical progress and miss ion status. Recent highlights: All mirrors have been fabricated, polished, and gold-coated; the mirror is expected to be diffraction-limite d down to a wavelength of 2 micron. The MIRI instrument just complete d its cryogenic testing. STScI has released exposure time calculators and sensitivity charts to enable scientists to start thinking about how to use JWST for their science.

Rigby, Jane R.↗

NASA NTRS2011

Active Galactic Nuclei with James Webb Space Telescope (JWST)

I'll discuss several ways in which JWST will probe the cosmic history of accretion onto supermassive black holes, and the co-evolution of host galaxies. Key investigations include: 1) Measurements of redshift, luminosity, and AGN fraction for obscured AGN candidates identified by other missions. 2) Measurements of AGN hosts at all redshifts, including stellar masses, morphology, interactions, and star formation rates. 3) Measurements of stellar mass and black hole mass in AGN at high redshift, to chart the early history of black hole and galaxy growth.

Rigby, Jane R.↗

NASA NTRS2011

The Carnegie Hubble Program: The Leavitt Law at 3.6 microns and 4.5 microns in the Large Magellanic Cloud

The Carnegie Hubble Program (CHP) is designed to improve the extragalactic distance scale using data from the post-cryogenic era of Spitzer. The ultimate goal is a determination of the Hubble constant to an accuracy of 2%. This paper is the first in a series on the Cepheid population of the Large Magellanic Cloud, and focuses on the period-luminosity relations (Leavitt laws) that will be used, in conjunction with observations of Milky Way Cepheids, to set the slope and zero-point of the Cepheid distance scale in the mid-infrared. To this end, we have obtained uniformly-sampled light curves for 85 LMC Cepheids, having periods between 6 and 140 days. Period- luminosity and period-color relations are presented in the 3.6 micron and 4.5 micron bands. We demonstrate that the 3.6 micron band is a superb distance indicator. The cyclical variation of the [3.6]-[4.5] color has been measured for the first time. We attribute the amplitude and phase of the color curves to the dissociation and recombination of CO molecules in the Cepheid s atmosphere. The CO affects only the 4.5 micron flux making it a potential metallicity indicator.

Scowcroft, Victoria↗