Near-Infrared MOSFIRE Spectra of Dusty Star-Forming Galaxies at 0.2<z<4

We present near-infrared and optical spectroscopic observations of a sample of 450$\mu$m and 850$\mu$m-selected dusty star-forming galaxies (DSFGs) identified in a 400 arcmin$^2$ area in the COSMOS field. Thirty-one sources of the 102 targets were spectroscopically confirmed at $0.2<z<4$, identified primarily in the near-infrared with Keck MOSFIRE and some in the optical with Keck LRIS and DEIMOS. The low rate of confirmation is attributable both to high rest-frame optical obscuration in our targets and limited sensitivity to certain redshift ranges. The high-quality photometric redshifts available in the COSMOS field allow us to test the robustness of photometric redshifts for DSFGs. We find a subset (11/31$\approx35$%) of DSFGs with inaccurate ($\Delta z/(1+z)>0.2$) or non-existent photometric redshifts; these have very distinct spectral energy distributions from the remaining DSFGs, suggesting a decoupling of highly obscured and unobscured components. We present a composite rest-frame 4300--7300\AA\ spectrum for DSFGs, and find evidence of 200$\pm$30 km s$^{-1}$ gas outflows. Nebular line emission for a sub-sample of our detections indicate that hard ionizing radiation fields are ubiquitous in high-z DSFGs, even more so than typical mass or UV-selected high-z galaxies. We also confirm the extreme level of dust obscuration in DSFGs, measuring very high Balmer decrements, and very high ratios of IR to UV and IR to H$\alpha$ luminosities. This work demonstrates the need to broaden the use of wide bandwidth technology in the millimeter to the spectroscopic confirmations of large samples of high-z DSFGs, as the difficulty in confirming such sources at optical/near-infrared wavelengths is exceedingly challenging given their obscuration.Comment: 14 pages, 13 figures, ApJ accepted. Composite DSFG Halpha spectrum available at www.as.utexas.edu/~cmcasey/downloads.htm

Punktlighet i jernbanen - hvert sekund teller

Denne boken gir en innføring i punktlighetsarbeid for jernbane, og er ment som et supplement til annen litteratur som finnes på området. Boken er basert på forsknings‐ og utviklingsarbeid utført ved SINTEF, Norges teknisk‐naturvitenskapelige universitet (NTNU) og Transportøkonomisk institutt (TØI) i samarbeid med de største aktørene i norsk jernbanesektor. Jernbanen er et komplekst og sammensatt trafikksystem der kravene til kvalitet og presisjon er stadig økende. En av de mest sentrale kvalitetsindikatorene ved transport er punktlighet. Gjennom en serie større forskningsprosjekter de siste 10–15 årene har aktører i norsk jernbanesektor i fellesskap utviklet kunnskap og løsninger for å nå målet om god punktlighet og forutsigbarhet i togtrafikken. Jernbaneverket har vært prosjekteier for disse prosjektene, SINTEF, TØI og NTNU har vært utøvende forskningspartnere, mens CargoNet, NSB og Flytoget har deltatt i arbeidet. Prosjektene ble finansiert av Norges forskningsråd og de deltakende organisasjonene. Denne boken bygger på resultatene fra forskningsprosjektene og fokuserer på analyser av punktlighetsdata. Vi vil takke alle som har bidratt til å realisere denne boken; både i utarbeidelsen av boken og gjennom finansiering og gjennomføring av de forutgående forskningsprosjektene. Framtiden er spennende – framtiden går på skinner!publishedVersio

Lipid peroxidation and chlorophyll fluorescence of photosystem ii performance during drought and heat stress is associated with the antioxidant capacities of C3 sunflower and C4 maize varieties

Agricultural production is predicted to be adversely affected by an increase in drought and heatwaves. Drought and heat damage cellular membranes, such as the thylakoid membranes where photosystem II occurs (PSII). We investigated the chlorophyll fluorescence (ChlF) of PSII, photosynthetic pigments, membrane damage, and the activity of protective antioxidants in drought-tolerant and -sensitive varieties of C3 sunflower and C4 maize grown at 20/25 and 30/35 &deg;C. Drought-tolerant varieties retained PSII electron transport at lower levels of water availability at both temperatures. Drought and heat stress, in combination and isolation, had a more pronounced effect on the ChlF of the C3 species. For phenotyping, the maximum fluorescence was the most effective ChlF measure in characterizing varietal variation in the response of both species to drought and heat. The drought-tolerant sunflower and maize showed lower lipid peroxidation under drought and heat stress. The greater retention of PSII function in the drought-tolerant sunflower and maize at higher temperatures was associated with an increase in the activities of antioxidants (glutathione reductase, superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase), whereas antioxidant activity declined in the drought-sensitive varieties. Antioxidant activity should play a key role in the development of drought- and heat-tolerant crops for future food security

Strain-induced Evolution of Electronic Band Structures in a Twisted Graphene Bilayer

Here we study the evolution of local electronic properties of a twisted graphene bilayer induced by a strain and a high curvature. The strain and curvature strongly affect the local band structures of the twisted graphene bilayer; the energy difference of the two low-energy van Hove singularities decreases with increasing the lattice deformations and the states condensed into well-defined pseudo-Landau levels, which mimic the quantization of massive Dirac fermions in a magnetic field of about 100 T, along a graphene wrinkle. The joint effect of strain and out-of-plane distortion in the graphene wrinkle also results in a valley polarization with a significant gap, i.e., the eight-fold degenerate Landau level at the charge neutrality point is splitted into two four-fold degenerate quartets polarized on each layer. These results suggest that strained graphene bilayer could be an ideal platform to realize the high-temperature zero-field quantum valley Hall effect.Comment: 4 figure

Gauging the mass of metals in the gas phase of galaxies from the Local Universe to the Epoch of Reionization

The chemical enrichment of dust and metals are vital processes in constraining the star formation history of the universe. Previously, the dust masses of high-redshift star-forming galaxies have been determined through their far-infrared continuum, however, equivalent, and potentially simpler, approaches to determining the metal masses have yet to be explored at $z\gtrsim 2$. Here, we present a new method of inferring the metal mass in the interstellar medium (ISM) of galaxies out to $z\approx 8$, using the far-infrared [CII]$-158\mu$m emission line as a proxy. We calibrated the [CII]-to-$M_{\rm Z,ISM}$ conversion factor based on a benchmark observational sample at $z\approx 0$, in addition to gamma-ray burst sightlines at $z>2$ and cosmological hydrodynamical simulations of galaxies at $z\approx 0$ and $z\approx 6$. We found a universal scaling across redshifts of $\log (M_{\rm Z,ISM}/M_\odot) = \log (L_{\rm [CII]}/L_\odot) - 0.45,$ with a 0.4 dex scatter, which is constant over more than two orders of magnitude in metallicity. We applied this scaling to recent surveys for [CII] in galaxies at $z\gtrsim 2$ and determined the fraction of metals retained in the gas-phase ISM, $M_{\rm Z,ISM} / M_\star$, as a function of redshift showing that an increasing fraction of metals reside in the ISM of galaxies at higher redshifts. We place further constraints on the cosmic metal mass density in the ISM ($\Omega_{\rm Z,ISM}$) at $z\approx 5$ and $\approx 7$, yielding $\Omega_{\rm Z,ISM} = 6.6^{+13}_{-4.3}\times 10^{-7}\,M_\odot\, {\rm Mpc}^{-3}$ ($z\approx 5$) and $\Omega_{\rm Z,ISM} = 2.0^{+3.5}_{-1.3}\times 10^{-7}\,M_\odot\, {\rm Mpc}^{-3}$ ($z\approx 7$). These results are consistent with the expected metal yields from the integrated star formation history at the respective redshifts. This suggests that the majority of metals produced at $z\gtrsim 5$ are confined to the ISM of galaxies.Comment: Accepted in A&A, abstract abridge

Electric field control of spins in bilayer graphene: Local moment formation and local moment interactions

We study local moment formation for adatoms on bilayer graphene (BLG) within a mean-field theory of the Anderson impurity model. The wavefunctions of the BLG electrons induce strong particle-hole asymmetry and band dependence of the hybridization, which is shown to result in unusual features in the impurity model phase diagram. We also study the effect of varying the chemical potential, as well as varying an electric field perpendicular to the bilayer; the latter modifies the density of states of electrons in BLG and, more significantly, shifts the impurity energy. We show that this leads to regimes in the impurity phase diagram where local moments can be turned on or off by applying modest external electric fields. Finally, we show that the RKKY interaction between local moments can be varied by tuning the chemical potential (as has also been suggested in monolayer graphene) or, more interestingly, by tuning the electric field so that it induces changes in the band structure of BLG.Comment: Revised discussion and figures, 17 page

The ALPINE-ALMA [C II] survey: characterization of spatial offsets in main-sequence galaxies at z ∼ 4–6

The morphology of galaxies is shaped by stellar activity, feedback, gas and dust properties, and interactions with surroundings, and can therefore provide insight into these processes. In this paper, we study the spatial offsets between stellar and interstellar medium emission in a sample of 54 main-sequence star-forming galaxies at z ∼ 4–6 observed with the Atacama Large Millimeter/submillimeter Array (ALMA), and drawn from the ALMA Large Program to INvestigate C+ at Early times (ALPINE). We find no significant spatial offset for the majority (∼70 per cent) of galaxies in the sample among any combination of [C II], far-infrared continuum, optical, and ultraviolet emission. However, a fraction of the sample (∼30 per cent) shows offsets larger than the median by more than 3σ significance (compared to the uncertainty on the offsets), especially between [C II] and ultraviolet emission. We find that these significant offsets are of the order of ∼0.5–0.7 arcsec, corresponding to ∼3.5–4.5 kiloparsecs. The offsets could be caused by a complex dust geometry, strong feedback from stars and active galactic nuclei, large-scale gas inflow and outflow, or a combination of these phenomena. However, our current analysis does not definitively constrain the origin. Future, higher resolution ALMA and JWST observations may help resolve the ambiguity. Regardless, since there exist at least some galaxies that display such large offsets, galaxy models and spectral energy distribution fitting codes cannot assume co-spatial emission in all main-sequence galaxies, and must take into account that the observed emission across wavelengths may be spatially segregated

Punktlighet i jernbanen - hvert sekund teller

Denne boken gir en innføring i punktlighetsarbeid for jernbane, og er ment som et supplement til annen litteratur som finnes på området. Boken er basert på forsknings‐ og utviklingsarbeid utført ved SINTEF, Norges teknisk‐naturvitenskapelige universitet (NTNU) og Transportøkonomisk institutt (TØI) i samarbeid med de største aktørene i norsk jernbanesektor. Jernbanen er et komplekst og sammensatt trafikksystem der kravene til kvalitet og presisjon er stadig økende. En av de mest sentrale kvalitetsindikatorene ved transport er punktlighet. Gjennom en serie større forskningsprosjekter de siste 10–15 årene har aktører i norsk jernbanesektor i fellesskap utviklet kunnskap og løsninger for å nå målet om god punktlighet og forutsigbarhet i togtrafikken. Jernbaneverket har vært prosjekteier for disse prosjektene, SINTEF, TØI og NTNU har vært utøvende forskningspartnere, mens CargoNet, NSB og Flytoget har deltatt i arbeidet. Prosjektene ble finansiert av Norges forskningsråd og de deltakende organisasjonene. Denne boken bygger på resultatene fra forskningsprosjektene og fokuserer på analyser av punktlighetsdata. Vi vil takke alle som har bidratt til å realisere denne boken; både i utarbeidelsen av boken og gjennom finansiering og gjennomføring av de forutgående forskningsprosjektene. Framtiden er spennende – framtiden går på skinner!publishedVersio

The ALMA-CRISTAL survey: Extended [CII] emission in an interacting galaxy system at z ~ 5.5

The ALMA [CII] Resolved Ism in STar-forming gALaxies (CRISTAL) survey is a Cycle 8 ALMA Large Programme that studies the cold gas component of high-redshift galaxies. Its sub-arcsecond resolution observations are key to disentangling physical mechanisms that shape galaxies during cosmic dawn. In this paper, we explore the morphology and kinematics of the cold gas, star-forming, and stellar components in the star-forming main-sequence galaxy CRISTAL-05/HZ3, at z = 5.54. Our analysis includes 0.3" spatial resolution (~2 kpc) ALMA observations of the [CII] line. While CRISTAL-05 was previously classified as a single source, our observations reveal that the system is a close interacting pair surrounded by an extended component of carbon-enriched gas. This is imprinted in the disturbed elongated [CII] morphology and the separation of the two components in the position-velocity diagram (~100 km/s). The central region is composed of two components, named C05-NW and C05-SE, with the former being the dominant one. A significant fraction of the [CII] arises beyond the close pair up to 10 kpc, while the regions forming new massive stars and the stellar component seem compact (r_[CII] ~ 4 r_UV), as traced by rest-frame UV and optical imaging obtained with the Hubble Space Telescope and the James Webb Space Telescope. Our kinematic model, using the DYSMALpy software, yields a minor contribution of dark matter of C05-NW within a radius of ~2x Reff. Finally, we explore the resolved [CII]/FIR ratios as a proxy for shock-heating produced by this merger. We argue that the extended [CII] emission is mainly caused by the merger, which could not be discerned with lower-resolution observations. Our work emphasizes the need for high-resolution observations to fully characterize the dynamic stages of infant galaxies and the physical mechanisms that drive the metal enrichment of the circumgalactic medium.Comment: Submitted to A&A - comments are welcome! - 19 pages, 13 figure

JWST NIRSpec High-resolution Spectroscopy of MACS0647-JD at z = 10.167:Resolved [O ii] Doublet and Electron Density in an Early Galaxy

We present JWST/NIRSpec high-resolution G395H/F290LP spectroscopy of MACS0647−JD, a gravitationally lensed galaxy merger at z = 10.167. The new spectroscopy, which is acquired for the two lensed images (JD1 and JD2), detects and resolves emission lines in the rest-frame ultraviolet and blue optical, including the resolved [O ii] λ λ3726, 3729 doublet, [Ne iii] λ3870, He i λ3890, Hδ, Hγ, and [O iii] λ4363. This is the first observation of the resolved [O ii] λ λ3726, 3729 doublet for a galaxy at z &gt; 8. We measure a line flux ratio [O ii] λ3729/λ3726 = 0.9 ± 0.3, which corresponds to an estimated electron density of log ( n e / cm − 3 ) = 2.9 ± 0.5 . This is significantly higher than the electron densities of local galaxies reported in the literature. We compile measurements from the literature and further analyze the redshift evolution of n e . We find that the redshift evolution follows the power-law form of n e = A × (1 + z)p with A = 54 − 23 + 31 cm−3 and p = 1.2 − 0.4 + 0.4 . This power-law form may be explained by a combination of metallicity and morphological evolution of galaxies, which become, on average, more metal poor and more compact with increasing redshift.</p