Bootes Field Research Articles

THE $z\lt 1.2$ OPTICAL LUMINOSITY FUNCTION FROM A SAMPLE OF ∼410,000 GALAXIES IN BOÖTES

Using a sample of ~410 000 galaxies to depth I_AB = 24 over 8.26 deg^2 in the Bootes field (~10 times larger than z~1 luminosity function studies in the prior literature), we have accurately measured the evolving B-band luminosity function of red galaxies at z<1.2 and blue galaxies at z<1.0. In addition to the large sample size, we utilise photometry that accounts for the varying angular sizes of galaxies, photometric redshifts verified with spectroscopy, and absolute magnitudes that should have very small random and systematic errors. Our results are consistent with the migration of galaxies from the blue cloud to the red sequence as they cease to form stars, and with downsizing in which more massive and luminous blue galaxies cease star formation earlier than fainter less massive ones. Comparing the observed fading of red galaxies with that to be expected from passive evolution alone, we find that the stellar mass contained within the red galaxy population has increased by a factor of ~3.6 from z~1.1 to z~0.1. The bright end of the red galaxy luminosity function fades with decreasing redshift, the rate of fading increasing from ~0.2 mag per unit redshift at z = 1.0 to ~0.8 at z = 0.2. The overall decrease in luminosity implies that the stellar mass in individual highly luminous red galaxies increased by a factor of ~2.2 from z = 1.1 to z = 0.1.

PROBING THE PHYSICAL PROPERTIES OFz= 4.5 LyαEMITTERS WITHSPITZER

We present the results from a stellar population modeling analysis of a sample of 162 z=4.5, and 14 z=5.7 Lyman alpha emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 um from the Spitzer Lyman Alpha Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 um for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs and 9/14 (64%) of the z=5.7 LAEs are detected at >3-sigma in at least one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of stellar mass, from 5x10^8 to 10^11 Msol. One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr - 1 Gyr, while the remainder have ages < 100 Myr. A stacking analysis of IRAC-undetected LAEs shows this population to be primarily low mass (8 -- 20 x 10^8 Msol) and young (64 - 570 Myr). We find a correlation between stellar mass and the dust-corrected ultraviolet-based star-formation rate (SFR) similar to that at lower redshifts, in that higher mass galaxies exhibit higher SFRs. However, the z=4.5 LAE correlation is elevated 4-5 times in SFR compared to continuum-selected galaxies at similar redshifts. The exception is the most massive LAEs which have SFRs similar to galaxies at lower redshifts suggesting that they may represent a different population of galaxies than the traditional lower-mass LAEs, perhaps with a different mechanism promoting Lyman alpha photon escape.

A UV TO MID-IR STUDY OF AGN SELECTION

We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 sq. deg Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC/MIPS) data, as well as spectroscopic redshifts for ~20,000 objects, primarily from the AGN and Galaxy Evolution Survey (AGES). We fit galaxy, AGN, stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminosities for the extragalactic sources. The photometric redshift precision of the galaxy and AGN samples are sigma/(1+z)=0.040 and sigma/(1+z)=0.169, respectively, with the worst 5% outliers excluded. Based on the reduced chi-squared of the SED fit for each SED model, we are able to distinguish between Galactic and extragalactic sources for sources brighter than I=23.5. We compare the SED fits for a galaxy-only model and a galaxy+AGN model. Using known X-ray and spectroscopic AGN samples, we confirm that SED fitting can be successfully used as a method to identify large populations of AGN, including spatially resolved AGN with significant contributions from the host galaxy and objects with the emission line ratios of "composite" spectra. We also use our results to compare to the X-ray, mid-IR, optical color and emission line ratio selection techniques. For an F-ratio threshold of F>10 we find 16,266 AGN candidates brighter than I=23.5 and a surface density of ~1900 AGN per deg^2.

THE LBT BOÖTES FIELD SURVEY. I. THE REST-FRAME ULTRAVIOLET AND NEAR-INFRARED LUMINOSITY FUNCTIONS AND CLUSTERING OF BRIGHT LYMAN BREAK GALAXIES ATZ∼ 3

We present a deep LBT/LBC U-band imaging survey (9 deg2) covering the NOAO Bootes field. A total of 14,485 Lyman Break Galaxies (LBGs) at z~3 are selected, which are used to measure the rest-frame UV luminosity function (LF). The large sample size and survey area reduce the LF uncertainties due to Poisson statistics and cosmic variance by >3 compared to previous studies. At the bright end, the LF shows excess power compared to the best-fit Schechter function, which can be attributed to the contribution of $z\sim3$ quasars. We compute the rest-frame near-infrared LF and stellar mass function (SMF) of z~3 LBGs based on the R-band and IRAC [4.5 micro m]-band flux relation. We investigate the evolution of the UV LFs and SMFs between z~7 and z~3, which supports a rising star formation history in the LBGs. We study the spatial correlation function of two bright LBG samples and estimate their average host halo mass. We find a tight relation between the host halo mass and the galaxy star formation rate (SFR),which follows the trend predicted by the baryonic accretion rate onto the halo, suggesting that the star formation in LBGs is fueled by baryonic accretion through the cosmic web. By comparing the SFRs with the total baryonic accretion rates, we find that cosmic star formation efficiency is about 5%-20% and it does not evolve significantly with redshift, halo mass, or galaxy luminosity.

MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THEWIDE-FIELD INFRARED SURVEY EXPLORER. II. PROPERTIES OFWISE-SELECTED ACTIVE GALACTIC NUCLEI IN THE NDWFS BOÖTES FIELD

Stern et al.(2012) presented a study of WISE selection of AGN in the 2 deg^2 COSMOS field, finding that a simple criterion W1-W2>=0.8 provides a highly reliable and complete AGN sample for W2<15.05, where the W1 and W2 passbands are centered at 3.4 and 4.6 microns, respectively. Here we extend this study using the larger 9 deg^2 NOAO Deep Wide-Field Survey Bootes field which also has considerably deeper WISE observations than the COSMOS field, and find that this simple color-cut significantly loses reliability at fainter fluxes. We define a modified selection criterion combining the W1-W2 color and the W2 magnitude to provide highly reliable or highly complete AGN samples for fainter WISE sources. In particular, we define a color-magnitude cut that finds 130+/-4 deg^-2 AGN candidates for W2<17.11 with 90% reliability. Using the extensive UV through mid-IR broad-band photometry available in this field, we study the spectral energy distributions of WISE AGN candidates. As expected, the WISE AGN selection is biased towards objects where the AGN dominates the bolometric luminosity output, and that it can identify highly obscured AGN. We study the distribution of reddening in the AGN sample and discuss a formalism to account for sample incompleteness based on the step-wise maximum-likelihood method of Efstathiou et al.(1988). The resulting dust obscuration distributions depend strongly on AGN luminosity, consistent with the trend expected for a Simpson (2005) receding torus. At L_AGN~3x10^44 erg/s, 29+/-7% of AGN are observed as Type 1, while at ~4x10^45 erg/s the fraction is 64+/-13%. The distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds.

T-RaMiSu: the Two-meter Radio Mini Survey

We present wide area, deep, high-resolution 153 MHz GMRT observations of the NOAO Bootes field, adding to the extensive, multi-wavelength data of this region. The observations, data reduction, and catalogue construction and description are described here. The seven pointings produced a final mosaic covering 30 square degrees with a resolution of 25". The rms noise is 2 mJy/beam in the centre of the image, rising to 4-5 mJy/beam on the edges, with an average of 3 mJy/beam. Seventy-five per cent of the area has an rms < 4 mJy/beam. The extracted source catalogue contains 1289 sources detected at 5\sigma, of which 453 are resolved. We estimate the catalogue to be 92 per cent reliable and 95 per cent complete at an integrated flux density limit of 14 mJy. The flux densities and astrometry have been corrected for systematic errors. We calculate the differential source counts {which are in good agreement with those in the literature and provide an important step forward in quantifying the source counts at these low frequencies and low flux densities}. The GMRT 153 MHz sources have been matched to the 1.4 GHz NVSS and 327 MHz WENSS catalogues and spectral indices were derived.

A SUCCESSFUL BROADBAND SURVEY FOR GIANT Lyα NEBULAE. II. SPECTROSCOPIC CONFIRMATION

Using a systematic broad-band search technique, we have carried out a survey for large Lya nebulae (or Lya "blobs") at 2<z<3 within 8.5 square degrees of the NOAO Deep Wide-Field Survey (NDWFS) Bootes field, corresponding to a total survey comoving volume of ~10^8 h_70^-3 Mpc^3. Here, we present our spectroscopic observations of candidate giant Lya nebulae. Of 26 candidates targeted, 5 were confirmed to have Lya emission at 1.7<z<2.7, four of which were new discoveries. The confirmed Lya nebulae span a range of Lya equivalent widths, colors, sizes, and line ratios, and most show spatially-extended continuum emission. The remaining candidates did not reveal any strong emission lines, but instead exhibit featureless, diffuse, blue continuum spectra. Their nature remains mysterious, but we speculate that some of these might be Lya nebulae lying within the redshift desert (i.e., 1.2<z<1.6). Our spectroscopic follow-up confirms the power of using deep broad-band imaging to search for the bright end of the Lya nebula population across enormous comoving volumes.

HERSCHEL DETECTION OF DUST EMISSION FROM UV-LUMINOUS STAR-FORMING GALAXIES AT 3.3 ≲ z ≲ 4.3

We report the Herschel SPIRE detection of dust emission arising from UV-luminous (L>~L*) star-forming galaxies at 3.3<z<4.3. Our sample of 1,913 Lyman Break Galaxy (LBG) candidates is selected over an area of 5.3 deg2 in the Bootes Field of the NOAO Deep Wide-Field Survey. This is one of the largest samples of UV-luminous galaxies at this epoch and enables an investigation of the bright end of the galaxy luminosity function. We divide our sample into three luminosity bins and stack the Herschel SPIRE data to measure the average spectral energy distribution (SED) of LBGs at far-infrared (FIR) wavelengths. We find that these galaxies have average IR luminosities of (3-5)x10^{11}L_sun and 60-70% of their star-formation obscured by dust. The FIR SEDs peak at lambda>100um, suggesting dust temperatures (T_d=27-30K) significantly colder than that of local galaxies of comparable IR luminosities. The observed IR-to-UV luminosity ratio (IRX=L_IR/L_UV) is low (~3-4) compared with that observed for z~2 LBGs (IRX(z~2)~7.1+/-1.1). The correlation between the slope of the UV continuum and IRX for galaxies in the two lower luminosity bins suggests dust properties similar to those of local starburst galaxies. However, the galaxies in the highest luminosity bin appear to deviate from the local relation, suggesting that their dust properties may differ from those of their lower-luminosity and low-redshift counterparts. We speculate that the most UV luminous galaxies at this epoch are being observed in a short-lived and young evolutionary phase.

AN ULTRAVIOLET ULTRA-LUMINOUS LYMAN BREAK GALAXY ATZ= 2.78 IN NDWFS BOÖTES FIELD,,

We present one of the most ultraviolet (UV) luminous Lyman Break Galaxies (LBGs) (J1432+3358) at z=2.78, discovered in the NOAO Deep Wide-Field Survey (NDWFS) Bootes field. The R-band magnitude of J1432+3358 is 22.29 AB, more than two magnitudes brighter than typical L* LBGs at this redshift. The deep z-band image reveals two components of J1432+3358 separated by 1.0" with flux ratio of 3:1. The high signal-to-noise ratio (S/N) rest-frame UV spectrum shows Lya emission line and interstellar medium absorption lines. The absence of NV and CIV emission lines, the non-detection in X-ray and radio wavelengths and mid-infrared (MIR) colors indicate no or weak active galactic nuclei (AGN) (<10%) in this galaxy. The galaxy shows broader line profile with the full width half maximum (FWHM) of about 1000 km/s and larger outflow velocity (~500 km/s) than those of typical z~3 LBGs. The physical properties are derived by fitting the spectral energy distribution (SED) with stellar synthesis models. The dust extinction, E(B-V)=0.12, is similar to that in normal LBGs. The star formation rates (SFRs) derived from the SED fitting and the dust-corrected UV flux are consistent with each other, ~300 Msun/yr, and the stellar mass is 1.3e11 Msun. The SFR and stellar mass in J1432+3358 are about an order of magnitude higher than those in normal LBGs. The SED-fitting results support that J1432+3358 has a continuous star formation history with the star formation episode of 630 Myr. The morphology of J1432+3358 and its physical properties suggest that J1432+3358 is in an early phase of 3:1 merger process. The unique properties and the low space number density (~1e-7 Mpc^{-3})are consistent with the interpretation that such galaxies are either found in a short unobscured phase of the star formation or that small fraction of intensive star-forming galaxies are unobscured.

AGES: THE AGN AND GALAXY EVOLUTION SURVEY

The AGN and Galaxy Evolution Survey (AGES) is a redshift survey covering, in its standard fields, 7.7 square degrees of the Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). The final sample consists of 23745 redshifts. There are well-defined galaxy samples in ten bands (the Bw, R, I, J, K, IRAC 3.6, 4.5, 5.8 and 8.0 micron and MIPS 24 micron bands) to a limiting magnitude of I<20 mag for spectroscopy. For these galaxies, we obtained 18163 redshifts from a sample of 35200 galaxies, where random sparse sampling was used to define statistically complete sub-samples in all ten photometric bands. The median galaxy redshift is 0.31, and 90% of the redshifts are in the range 0.085<z<0.66. AGN were selected as radio, X-ray, IRAC mid-IR and MIPS 24 micron sources to fainter limiting magnitudes (I<22.5 mag for point sources). Redshifts were obtained for 4764 quasars and galaxies with AGN signatures, with 2926, 1718, 605, 119 and 13 above redshifts of 0.5, 1, 2, 3 and 4, respectively. We detail all the AGES selection procedures and present the complete spectroscopic redshift catalogs, spectra, and spectral energy distribution decompositions. The photometric redshift estimates are for all sources in the AGES samples.

A SUCCESSFUL BROADBAND SURVEY FOR GIANT Lyα NEBULAE. I. SURVEY DESIGN AND CANDIDATE SELECTION

Giant Lya nebulae (or Lya "blobs") are likely sites of ongoing massive galaxy formation, but the rarity of these powerful sources has made it difficult to form a coherent picture of their properties, ionization mechanisms, and space density. Systematic narrow-band Lya nebula surveys are ongoing, but the small redshift range covered and the observational expense limit the comoving volume that can be probed by even the largest of these surveys and pose a significant problem when searching for such rare sources. We have developed a systematic search technique designed to find large Lya nebulae at 2<z<3 within deep broad-band imaging and have carried out a survey of the 9.4 square degree NOAO Deep Wide-Field Survey (NDWFS) Bootes field. With a total survey comoving volume of ~10^8 h^-3_70 Mpc^3, this is the largest volume survey for Lya nebulae ever undertaken. In this first paper in the series, we present the details of the survey design and a systematically-selected sample of 79 candidates, which includes one previously discovered Lya nebula.

THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY

We present the galaxy optical luminosity function for the redshift range 0.05<z<0.75 from the AGN and Galaxy Evolution Survey (AGES), a spectroscopic survey of 7.6 sq. deg. in the Bootes field of the NOAO Deep Wide-Field Survey. Our statistical sample is comprised of 12,473 galaxies with known redshifts down to I=20.4 (AB). Our results at low redshift are consistent with those from SDSS; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1+z)^(0.54+/-0.64) for red galaxies and (1+z)^(1.64+/-0.39) for blue galaxies.

A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS ATz= 1.175

The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Bootes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0.69" (5.5 kpc) in the spatial dimension and by 690 km s^-1 in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an AGN continuum, and the double-peaked profile resembles that of candidate dual AGN. At a redshift of z=1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field, as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 10^23 cm^-2. Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of ~10^45 erg s^-1. Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGN following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates.

Deep low-frequency radio observations of the NOAO Boötes field

In this article we present deep, high-resolution radio interferometric observations at 153 MHz to complement the extensively studied NOAO Bootes field. We provide a description of the observations, data reduction and source catalog construction. From our single pointing GMRT observation of ~12 hours we obtain a high-resolution (26" x 22") image of ~11.3 square degrees, fully covering the Bootes field region and beyond. The image has a central noise level of ~1.0 mJy/beam, which rises to 2.0-2.5 mJy/beam at the field edge, placing it amongst the deepest ~150 MHz surveys to date. The catalog of 598 extracted sources is estimated to be ~92 percent complete for >10 mJy sources, while the estimated contamination with false detections is <1 percent. The low RMS position uncertainty of 1.24" facilitates accurate matching against catalogs at optical, infrared and other wavelengths. Differential source counts are determined down to <~10 mJy. There is no evidence for flattening of the counts towards lower flux densities as observed in deep radio surveys at higher frequencies, suggesting that our catalog is dominated by the classical radio-loud AGN population that explains the counts at higher flux densities. Combination with available deep 1.4 GHz observations yields an accurate determination of spectral indices for 417 sources down to the lowest 153 MHz flux densities, of which 16 have ultra-steep spectra with spectral indices below -1.3. We confirm that flattening of the median spectral index towards low flux densities also occurs at this frequency. The detection fraction of the radio sources in NIR Ks-band is found to drop with radio spectral index, which is in agreement with the known correlation between spectral index and redshift for brighter radio sources.

CONSTRAINING HALO OCCUPATION PROPERTIES OF X-RAY ACTIVE GALACTIC NUCLEI USING CLUSTERING OFCHANDRASOURCES IN THE BOÖTES SURVEY REGION

We present one of the most precise measurement to date of the spatial clustering of X-ray selected AGNs using a sample derived from the Chandra X-ray Observatory survey in the Bootes field. The real-space two-point correlation function over a redshift interval from z=0.17 to z~3 is well described by the power law, xi(r)=(r/r0)^-gamma, for comoving separations r<~20h^-1 Mpc. We find gamma=1.84+-0.12 and r0 consistent with no redshift trend within the sample (varying between r0=5.5+-0.6 h^-1 Mpc for <z>=0.37 and r0=6.9+-1.0 h^-1 Mpc for <z>=1.28). Further, we are able to measure the projections of the two-point correlation function both on the sky plane and in the line of sight. We use these measurements to show that the Chandra/Bootes AGNs are predominantly located at the centers of dark matter halos with the circular velocity Vmax>320 km/s or M_200 > 4.1e12 h^-1 Msun, and tend to avoid satellite galaxies in halos of this or higher mass. The halo occupation properties inferred from the clustering properties of Chandra/Bootes AGNs --- the mass scale of the parent dark matter halos, the lack of significant redshift evolution of the clustering length, and the low satellite fraction --- are broadly consistent with the Hopkins et al. scenario of quasar activity triggered by mergers of similarly-sized galaxies.

THE ALLEN TELESCOPE ARRAY Pi GHz SKY SURVEY II. DAILY AND MONTHLY MONITORING FOR TRANSIENTS AND VARIABILITY IN THE BOÖTES FIELD

We present results from daily radio continuum observations of the Bootes field as part of the Pi GHz Sky Survey (PiGSS). These results are part of a systematic and unbiased campaign to characterize variable and transient sources in the radio sky. The observations include 78 individual epochs distributed over 5 months at a radio frequency of 3.1 GHz with a median RMS image noise in each epoch of 2.8 mJy. We produce 5 monthly images with a median RMS of 0.6 mJy. No transient radio sources are detected in the daily or monthly images. At 15 mJy, we set an upper limit (2 sigma) to the surface density of 1-day radio transients at 0.025 deg^-2. At 5 mJy, we set an upper limit (2\sigma) to the surface density of 1-month radio transients at 0.18 deg^-2. We also produce light curves for 425 sources and explore the variability properties of these sources. Approximately 20% of the sources exhibit some variability on daily and monthly time scales. The maximum RMS fractional modulations on the 1 day and 1 month time scales for sources brighter than 10 mJy are 2 and 0.5, respectively. The probability of a daily fluctuation for all sources and all epochs by a factor of 10 is less than 10^-4. We compare the radio to mid-infrared variability for sources in the field and find no correlation. Finally, we apply the statistics of transient and variable populations to constrain models for a variety of source classes.

THE DIRT ON DRY MERGERS

Using data from the Spitzer Space Telescope, we analyze the mid-infrared (3-70 micron) spectral energy distributions of dry merger candidates in the Bootes field of the NOAO Deep Wide-Field Survey. These candidates were selected by previous authors to be luminous, red, early-type galaxies with morphological evidence of recent tidal interactions. We find that a significant fraction of these candidates exhibit 8 and 24 micron excesses compared to expectations for old stellar populations. We estimate that a quarter of dry merger candidates have mid-infrared-derived star formation rates greater than ~1 MSun/yr. This represents a "frosting" on top of a large old stellar population, and has been seen in previous studies of elliptical galaxies. Further, the dry merger candidates include a higher fraction of starforming galaxies relative to a control sample without tidal features. We therefore conclude that the star formation in these massive ellipticals is likely triggered by merger activity. Our data suggest that the mergers responsible for the observed tidal features were not completely dry, and may be minor mergers involving a gas-rich dwarf galaxy.

SDWFS-MT-1: A SELF-OBSCURED LUMINOUS SUPERNOVA ATz≃ 0.2

We report the discovery of a six-month-long mid-infrared transient, SDWFS-MT-1 (aka SN 2007va), in the Spitzer Deep, Wide-Field Survey of the NOAO Deep Wide-Field Survey Bootes field. The transient, located in a z=0.19 low luminosity (M_[4.5]~-18.6 mag, L/L_MilkyWay~0.01) metal-poor (12+log(O/H)~7.8) irregular galaxy, peaked at a mid-infrared absolute magnitude of M_[4.5]~-24.2 in the 4.5 micron Spitzer/IRAC band and emitted a total energy of at least 10^51 ergs. The optical emission was likely fainter than the mid-infrared, although our constraints on the optical emission are poor because the transient peaked when the source was "behind" the Sun. The Spitzer data are consistent with emission by a modified black body with a temperature of ~1350 K. We rule out a number of scenarios for the origin of the transient such as a Galactic star, AGN activity, GRB, tidal disruption of a star by a black hole and gravitational lensing. The most plausible scenario is a supernova exploding inside a massive, optically thick circumstellar medium, composed of multiple shells of previously ejected material. If the proposed scenario is correct, then a significant fraction (~10%) of the most luminous supernova may be self-enshrouded by dust not only before but also after the supernova occurs. The spectral energy distribution of the progenitor of such a supernova would be a slightly cooler version of eta Carina, peaking at 20-30 microns.

THE EVOLUTION OF THE STAR FORMATION RATE OF GALAXIES AT 0.0 ⩽z⩽ 1.2

We present the 24 micron rest-frame luminosity function (LF) of star-forming galaxies in the redshift range 0.0 < z < 0.6 constructed from 4047 spectroscopic redshifts from the AGN and Galaxy Evolution Survey of 24 micron selected sources in the Bootes field of the NOAO Deep Wide-Field Survey. This sample provides the best available combination of large area (9 deg^2), depth, and statistically complete spectroscopic observations, allowing us to probe the evolution of the 24 micron LF of galaxies at low and intermediate redshifts while minimizing the effects of cosmic variance. In order to use the observed 24 micron luminosity as a tracer for star formation, active galactic nuclei (AGNs) that could contribute significantly at 24 micron are identified and excluded from our star-forming galaxy sample based on their mid-IR spectral energy distributions or the detection of X-ray emission. The evolution of the 24 micron LF of star-forming galaxies for redshifts of z < 0.65 is consistent with a pure luminosity evolution where the characteristic 24 micron luminosity evolves as (1+z)^(3.8+/-0.3). We extend our evolutionary study to encompass 0.0 < z < 1.2 by combining our data with that of the Far-Infrared Deep Extragalactic Legacy Survey. Over this entire redshift range the evolution of the characteristic 24 micron luminosity is described by a slightly shallower power law of (1+z)^(3.4+/-0.2). We find a local star formation rate density of (1.09+/-0.21) x 10^-2 Msun/yr/Mpc^-3, and that it evolves as (1+z)^(3.5+/-0.2) over 0.0 < z < 1.2. These estimates are in good agreement with the rates using optical and UV fluxes corrected for the effects of intrinsic extinction in the observed sources. This agreement confirms that star formation at z <~ 1.2 is robustly traced by 24 micron observations and that it largely occurs in obscured regions of galaxies. (Abridged)

LOW-RESOLUTION SPECTRAL TEMPLATES FOR ACTIVE GALACTIC NUCLEI AND GALAXIES FROM 0.03 TO 30 μm

We present a set of low resolution empirical SED templates for AGNs and galaxies in the wavelength range from 0.03 to 30 microns based on the multi-wavelength photometric observations of the NOAO Deep-Wide Field Survey Bootes field and the spectroscopic observations of the AGN and Galaxy Evolution Survey. Our training sample is comprised of 14448 galaxies in the redshift range 0<~z<~1 and 5347 likely AGNs in the range 0<~z<~5.58. We use our templates to determine photometric redshifts for galaxies and AGNs. While they are relatively accurate for galaxies, their accuracies for AGNs are a strong function of the luminosity ratio between the AGN and galaxy components. Somewhat surprisingly, the relative luminosities of the AGN and its host are well determined even when the photometric redshift is significantly in error. We also use our templates to study the mid-IR AGN selection criteria developed by Stern et al.(2005) and Lacy et al.(2004). We find that the Stern et al.(2005) criteria suffers from significant incompleteness when there is a strong host galaxy component and at z =~ 4.5, when the broad Halpha emission line is redshifted into the [3.6] band, but that it is little contaminated by low and intermediate redshift galaxies. The Lacy et al.(2004) criterion is not affected by incompleteness at z =~ 4.5 and is somewhat less affected by strong galaxy host components, but is heavily contaminated by low redshift star forming galaxies. Finally, we use our templates to predict the color-color distribution of sources in the upcoming WISE mission and define a color criterion to select AGNs analogous to those developed for IRAC photometry. We estimate that in between 640,000 and 1,700,000 AGNs will be identified by these criteria, but will have serious completeness problems for z >~ 3.4.