ABSTRACT We present 0 4 resolution extinction-independent distributions of star formation and dust in 11 star-forming galaxies (SFGs) at z = 1.3-3.0. These galaxies are selected from sensitive ...blank-field surveys of the 2′ × 2′ Hubble Ultra-Deep Field at λ = 5 cm and 1.3 mm using the Karl G. Jansky Very Large Array and Atacama Large Millimeter/submillimeter Array. They have star formation rates (SFRs), stellar masses, and dust properties representative of massive main-sequence SFGs at z ∼ 2. Morphological classification performed on spatially resolved stellar mass maps indicates a mixture of disk and morphologically disturbed systems; half of the sample harbor X-ray active galactic nuclei (AGNs), thereby representing a diversity of z ∼ 2 SFGs undergoing vigorous mass assembly. We find that their intense star formation most frequently occurs at the location of stellar-mass concentration and extends over an area comparable to their stellar-mass distribution, with a median diameter of 4.2 1.8 kpc. This provides direct evidence of galaxy-wide star formation in distant blank-field-selected main-sequence SFGs. The typical galactic-average SFR surface density is 2.5 M yr−1 kpc−2, sufficiently high to drive outflows. In X-ray-selected AGN where radio emission is enhanced over the level associated with star formation, the radio excess pinpoints the AGNs, which are found to be cospatial with star formation. The median extinction-independent size of main-sequence SFGs is two times larger than those of bright submillimeter galaxies, whose SFRs are 3-8 times larger, providing a constraint on the characteristic SFR (∼300 M yr−1) above which a significant population of more compact SFGs appears to emerge.
Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, ...7.045, 7.109, 7.213 and 7.215 (refs 1-4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z > 6.5, given that Lyman α is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We show that measures of star formation rates (SFRs) for infrared galaxies using either single-band 24 is a subset of m or extinction-corrected Pa alpha luminosities are consistent in the total ...infrared luminosity = L(TIR) ~ 1010 L range. MIPS 24 is a subset of m photometry can yield SFRs accurately from this luminosity upward: SFR(M yr-1) = 7.8 X 10-10 L(24 is a subset of m, L ) from L(TIR) = 5X 109 L to 1011 L and SFR = 7.8 X 10-10 L(24 is a subset of m, L )(7.76 X 10-11 L(24))0.048 for higher L(TIR). For galaxies with L(TIR) >= 1010 L , these new expressions should provide SFRs to within 0.2 dex. For L(TIR) >= 1011 L , we find that the SFR of infrared galaxies is significantly underestimated using extinction-corrected Pa alpha (and presumably using any other optical or near-infrared recombination lines). As a part of this work, we constructed spectral energy distribution templates for eleven luminous and ultraluminous purely star forming infrared galaxies and over the spectral range 0.4 is a subset of m to 30 cm. We use these templates and the SINGS data to construct average templates from 5 is a subset of m to 30 cm for infrared galaxies with L(TIR) = 5X 109 to 1013 L . All of these templates are made available online.
ABSTRACT We have acquired Hubble Space Telescope (HST) and Very Large Telescope near-infrared spectra and images of supernova (SN) Refsdal after its discovery as an Einstein cross in fall 2014. The ...HST light curve of SN Refsdal has a shape consistent with the distinctive, slowly rising light curves of SN 1987A-like SNe, and we find strong evidence for a broad H P-Cygni profile and Na I D absorption in the HST grism spectrum at the redshift (z = 1.49) of the spiral host galaxy. SNe IIn, largely powered by circumstellar interaction, could provide a good match to the light curve of SN Refsdal, but the spectrum of a SN IIn would not show broad and strong H and Na I D absorption. From the grism spectrum, we measure an H expansion velocity consistent with those of SN 1987A-like SNe at a similar phase. The luminosity, evolution, and Gaussian profile of the H emission of the WFC3 and X-shooter spectra, separated by ∼2.5 months in the rest frame, provide additional evidence that supports the SN 1987A-like classification. In comparison with other examples of SN 1987A-like SNe, photometry of SN Refsdal favors bluer B − V and V − R colors and one of the largest luminosities for the assumed range of potential magnifications. The evolution of the light curve at late times will provide additional evidence about the potential existence of any substantial circumstellar material. Using MOSFIRE and X-shooter spectra, we estimate a subsolar host-galaxy metallicity (8.3 0.1 dex and <8.4 dex, respectively) near the explosion site.
We analyze star formation (SF) as a function of stellar mass (M sub(*)) and redshift z in the All-Wavelength Extended Groth Strip International Survey. For 2905 field galaxies, complete to 10 ...super(10)(10 super(10.8)) M sub((.)) at z < 0.7(1), with Keck spectroscopic redshifts out to z = 1.1, we compile SF rates (SFRs) from emission lines, GALEX, and Spitzer MIPS 24 km photometry, optical-NIR M sub(*) measurements, and HST morphologies. Galaxies with reliable signs of SF form a distinct "main sequence" (MS), with a limited range of SFRs at a given M sub(*) and z (1 s c0.3 dex), and log(SFR) approximately proportional to log M sub(*). The range of log (SFR) remains constant to z > 1, while the MS as a whole moves to higher SFR as z increases. The range of the SFR along the MS constrains the amplitude of episodic variations of SF and the effect of mergers on the SFR. Typical galaxies spend 667%(95%) of their lifetime since z = 1 within a factor of 2(4) of their average SFR at a given M sub(*) and z. The dominant mode of the evolution of SF since z 6 1 is apparently a gradual decline of the average SFR in most individual galaxies, not a decreasing frequency of starburst episodes, or a decreasing factor by which SFRs are enhanced in starbursts. LIRGs at z 6 1 seem to mostly reflect the high SFR typical for massive galaxies at that epoch. The smooth MS may reflect that the same set of few physical processes governs SF prior to additional quenching processes. A gradual process like gas exhaustion may play a dominant role.
Optical parametric chirped-pulse amplification (OPCPA) Dubietis
et al.
, Opt. Commun.
88
, 437 (1992) implemented by multikilojoule Nd:glass pump lasers is a promising approach to produce ...ultraintense pulses (
${>}10^{23}~\text{W}/\text{cm}^{2}$
). Technologies are being developed to upgrade the OMEGA EP Laser System with the goal to pump an optical parametric amplifier line (EP OPAL) with two of the OMEGA EP beamlines. The resulting ultraintense pulses (1.5 kJ, 20 fs,
$10^{24}~\text{W}/\text{cm}^{2}$
) would be used jointly with picosecond and nanosecond pulses produced by the other two beamlines. A midscale OPAL pumped by the Multi-Terawatt (MTW) laser is being constructed to produce 7.5-J, 15-fs pulses and demonstrate scalable technologies suitable for the upgrade. MTW OPAL will share a target area with the MTW laser (50 J, 1 to 100 ps), enabling several joint-shot configurations. We report on the status of the MTW OPAL system, and the technology development required for this class of all-OPCPA laser system for ultraintense pulses.
The field of worksite health promotion has moved toward the development and testing of comprehensive programs that target health behaviors with interventions operating at multiple levels of ...influence. Yet, observational and process evaluation studies indicate that such programs are challenging for worksites to implement effectively. Research has identified several organizational factors that promote or inhibit effective implementation of comprehensive worksite health promotion programs. However, no integrated theory of implementation has emerged from this research. This article describes a theory of the organizational determinants of effective implementation of comprehensive worksite health promotion programs. The model is adapted from theory and research on the implementation of complex innovations in manufacturing, education and health care settings. The article uses the Working Well Trial to illustrate the model's theoretical constructs. Although the article focuses on comprehensive worksite health promotion programs, the conceptual model may also apply to other types of complex health promotion programs. An organization-level theory of the determinants of effective implementation of worksite health promotion programs
ABSTRACT In Hubble Space Telescope (HST) imaging taken on 2014 November 10, four images of supernova (SN) "Refsdal" (redshift z = 1.49) appeared in an Einstein-cross-like configuration (images S1-S4) ...around an early-type galaxy in the cluster MACS J1149.5+2223 (z = 0.54). Almost all lens models of the cluster have predicted that the SN should reappear within a year in a second host-galaxy image created by the cluster's potential. In HST observations taken on 2015 December 11, we find a new source at the predicted position of the new image of SN Refsdal approximately from the previous images S1-S4. This marks the first time the appearance of a SN at a particular time and location in the sky was successfully predicted in advance! We use these data and the light curve from the first four observed images of SN Refsdal to place constraints on the relative time delay and magnification of the new image (SX) compared to images S1-S4. This enables us, for the first time, to test "blind" lens model predictions of both magnifications and time delays for a lensed SN. We find that the timing and brightness of the new image are consistent with the blind predictions of a fraction of the models. The reappearance illustrates the discriminatory power of this blind test and its utility to uncover sources of systematic uncertainty. From planned HST photometry, we expect to reach a precision of 1%-2% on the time delay between S1-S4 and SX.
We present a complete census of all Herschel-detected sources within the six massive lensing clusters of the HST Frontier Fields (HFF). We provide a robust legacy catalogue of 263 sources with ...Herschel fluxes, primarily based on imaging from the Herschel Lensing Survey and PEP/HerMES Key Programmes. We optimally combine Herschel, Spitzer and WISE infrared (IR) photometry with data from HST, VLA and ground-based observatories, identifying counterparts to gain source redshifts. For each Herschel-detected source we also present magnification factor (μ), intrinsic IR luminosity and characteristic dust temperature, providing a comprehensive view of dust-obscured star formation within the HFF. We demonstrate the utility of our catalogues through an exploratory overview of the magnified population, including more than 20 background sub-LIRGs unreachable by Herschel without the assistance gravitational lensing.
We analyze star formation (SF) as a function of stellar mass (M sub(*)) and redshift z in the All-Wavelength Extended Groth Strip International Survey, for star-forming field galaxies with M sub(*) ...10 super(10) M sub((.)) out to z = 1.1. The data indicate that the high specific SF rates (SFRs) of many less massive galaxies do not represent late, irregular or recurrent, starbursts in evolved galaxies. They rather seem to reflect the onset (initial burst) of the dominant SF episode of galaxies, after which SF gradually declines on gigayear timescales to z = 0 and forms the bulk of a galaxy's M sub(*). With decreasing mass, this onset of major SF shifts to decreasing z for an increasing fraction of galaxies (staged galaxy formation). This process may be an important component of the "downsizing" phenomenon. We find that the predominantly gradual decline of SFRs described by Noeske et al. can be reproduced by exponential SF histories (t models), if less massive galaxies have systematically longer e-folding times t, and a later onset of SF (z sub(f)). Our model can provide a first parameterization of SFR as a function of M sub(*) and z, and quantify mass dependences of t and z sub(f) from direct observations of M sub(*) and SFRs up to z> 1. The observed evolution of SF in galaxies can plausibly reflect the dominance of gradual gas exhaustion. The data are also consistent with the history of cosmological accretion onto dark matter halos.
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