Highly ionized region surrounding SN Refsdal revealed by MUSE

Supernova (SN) Refsdal is the first multiply imaged, highly magnified, and spatially resolved SN ever observed. The SN exploded in a highly magnified spiral galaxy at z = 1.49 behind the Frontier Fields cluster MACS1149, and provides a unique opportunity to study the environment of SNe at high z. We exploit the time delay between multiple images to determine the properties of the SN and its environment before, during, and after the SN exploded. We use the integral-field spectrograph MUSE on the VLT to simultaneously target all observed and model-predicted positions of SN Refsdal. We find Mg ii emission at all positions of SN Refsdal, accompanied by weak Fe ii* emission at two positions. The measured ratios of [O ii] to Mg ii emission of 10–20 indicate a high degree of ionization with low metallicity. Because the same high degree of ionization is found in all images, and our spatial resolution is too coarse to resolve the region of influence of SN Refsdal, we conclude that this high degree of ionization has been produced by previous SNe or a young and hot stellar population. We find no variability of the [O ii] line over a period of 57 days. This suggests that there is no variation in the [O ii] luminosity of the SN over this period, or that the SN has a small contribution to the integrated [O ii] emission over the scale resolved by our observations

Statistical stellar mass corrections for high-z galaxies observed with JWST broadband filters due to template degeneracies

Stellar masses in future James Webb Space Telescope (JWST) deep blank fields will be mainly derived by fitting the spectral energy distribution (SED) with theoretical galaxy templates. We investigate the uncertainties and biases of the stellar masses derived by using the LePhare code for SED fitting and the Yggdrasil theoretical templates. We consider a sample of mock galaxies at z = 7–10 with mock JWST observations with S/N_(F150W) ≥ 10. Our goal is to provide a list of statistical stellar mass corrections to include on the stellar mass derivation for different output galaxy properties and JWST filter combinations to correct for template degeneracies. Median statistical stellar mass corrections vary from −0.83 to 0.87 dex, while 25% (75%) quartiles range from −0.83 (−0.67) to 0.51 (0.88) dex, depending on filter combinations and galaxy models. The most challenging cases are galaxies with nebular emission lines, especially the ones that are wrongly identified as galaxies without, relative dust-free galaxies, and galaxies with small metallicities (i.e., Z = 1/50 Zꙩ). The stellar mass estimation of galaxies correctly identified without emission lines is generally fine, except at z = 10 when considering only the eight NIRCam bands, which make the MIRI bands very valuable. We have tested our stellar mass corrections using the public JAGUAR galaxy catalog, deriving that the average discrepancy in the recovered stellar mass distribution decreases by 20%–50% at z > 7 after the correction. We found that without the stellar mass corrections, the number of low-mass galaxies (M* < 10^(7) Mꙩ) is overestimated, which can potentially lead to systematic errors in the calculation of the galaxy stellar mass function faint-end slope at high z

The SCUBA-2 Cosmology Legacy Survey: the nature of bright submm galaxies from 2 deg2 of 850-μm imaging

We present physical properties [redshifts (z), star-formation rates (SFRs) and stellar masses ( Mstar Mstar )] of bright (S850 ≥ 4 mJy) submm galaxies in the ≃2 deg2 COSMOS and UDS fields selected with SCUBA-2/JCMT. We complete the galaxy identification process for all (≃2000) S/N ≥ 3.5 850-μm sources, but focus our scientific analysis on a high-quality subsample of 651 S/N ≥ 4 sources with complete multiwavelength coverage including 1.1-mm imaging. We check the reliability of our identifications, and the robustness of the SCUBA-2 fluxes by revisiting the recent ALMA follow-up of 29 sources in our sample. Considering >4 mJy ALMA sources, our identification method has a completeness of ≃86 per cent with a reliability of ≃92 per cent, and only ≃15–20 per cent of sources are significantly affected by multiplicity (when a secondary component contributes >1/3 of the primary source flux). The impact of source blending on the 850-μm source counts as determined with SCUBA-2 is modest; scaling the single-dish fluxes by ≃0.9 reproduces the ALMA source counts. For our final SCUBA-2 sample, we find median z=2.40+0.10−0.04 z=2.40−0.04+0.10 , SFR = 287 ± 6 M⊙  yr− 1 and log(Mstar/M⊙)=11.12±0.02 log⁡(Mstar/M⊙)=11.12±0.02 (the latter for 349/651 sources with optical identifications). These properties clearly locate bright submm galaxies on the high-mass end of the ‘main sequence’ of star-forming galaxies out to z ≃ 6, suggesting that major mergers are not a dominant driver of the high-redshift submm-selected population. Their number densities are also consistent with the evolving galaxy stellar mass function. Hence, the submm galaxy population is as expected, albeit reproducing the evolution of the main sequence of star-forming galaxies remains a challenge for theoretical models/simulations

Physical Characterization of an Unlensed, Dusty Star-forming Galaxy at z = 5.85

We present a physical characterization of MM J100026.36+021527.9 (a.k.a. "Mambo-9"), a dusty star-forming galaxy (DSFG) at z = 5.850 \ub1 0.001. This is the highest-redshift unlensed DSFG (and fourth most distant overall) found to date and is the first source identified in a new 2 mm blank-field map in the COSMOS field. Though identified in prior samples of DSFGs at 850 \u3bcm to 1.2 mm with unknown redshift, the detection at 2 mm prompted further follow-up as it indicated a much higher probability that the source was likely to sit at z &gt; 4. Deep observations from the Atacama Large Millimeter and submillimeter Array (ALMA) presented here confirm the redshift through the secure detection of 12CO(J = 6\u21925) and p-H2O (21,1 \u2192 20,2). Mambo-9 is composed of a pair of galaxies separated by 6 kpc with corresponding star formation rates of 590 M o\u2d9 yr-1 and 220 M o\u2d9 yr-1, total molecular hydrogen gas mass of (1.7 \ub1 0.4) 7 1011 M o\u2d9, dust mass of (1.3 \ub1 0.3) 7 109 M o\u2d9, and stellar mass of (3.2-1.5+1.0) 7 109 M o\u2d9. The total halo mass, (3.3 \ub1 0.8) 7 1012 M o\u2d9, is predicted to exceed 1015 M o\u2d9 by z = 0. The system is undergoing a merger-driven starburst that will increase the stellar mass of the system tenfold in \u3c4 depl = 40-80 Myr, converting its large molecular gas reservoir (gas fraction of 96-2+1) into stars. Mambo-9 evaded firm spectroscopic identification for a decade, following a pattern that has emerged for some of the highest-redshift DSFGs found. And yet, the systematic identification of unlensed DSFGs like Mambo-9 is key to measuring the global contribution of obscured star formation to the star formation rate density at z \u2a86 4, the formation of the first massive galaxies, and the formation of interstellar dust at early times ( 721 Gyr)

The VANDELS ESO public spectroscopic survey

VANDELS is a uniquely deep spectroscopic survey of high-redshift galaxies with the VIMOS spectrograph on ESO’s Very Large Telescope (VLT). The survey has obtained ultradeep optical (0.48 < λ < 1.0 μ m) spectroscopy of ≃2100 galaxies within the redshift interval 1.0 ≤ z ≤ 7.0, over a total area of ≃0.2 deg2 centred on the CANDELS Ultra Deep Survey and Chandra Deep Field South fields. Based on accurate photometric redshift pre-selection, 85 per cent of the galaxies targeted by VANDELS were selected to be at z ≥ 3. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the fundamental aim of the survey is to provide the high-signal-to-noise ratio spectra necessary to measure key physical properties such as stellar population ages, masses, metallicities, and outflow velocities from detailed absorption-line studies. Using integration times calculated to produce an approximately constant signal-to-noise ratio (20 < tint< 80 h), the VANDELS survey targeted: (a) bright star-forming galaxies at 2.4 ≤ z ≤ 5.5, (b) massive quiescent galaxies at 1.0 ≤ z ≤ 2.5, (c) fainter star-forming galaxies at 3.0 ≤ z ≤ 7.0, and (d) X-ray/Spitzer-selected active galactic nuclei and Herschel-detected galaxies. By targeting two extragalactic survey fields with superb multiwavelength imaging data, VANDELS will produce a unique legacy data set for exploring the physics underpinning high-redshift galaxy evolution. In this paper, we provide an overview of the VANDELS survey designed to support the science exploitation of the first ESO public data release, focusing on the scientific motivation, survey design, and target selection

AzTEC half square degree survey of the SHADES fields - II. Identifications, redshifts, and evidence for large-scale structure

The AzTEC 1.1mm survey of the two SCUBA HAlf Degree Extragalactic Survey (SHADES) fields is the largest (0.7 deg2) blank-field millimetre-wavelength survey un- dertaken to date at a resolution of ≃ 18 arcsec and a depth of ≃ 1mJy. We have used the deep optical-to-radio multi-wavelength data in the SHADES Lockman Hole East and SXDF/UDS fields to obtain galaxy identifications for ≃ 64% (≃ 80% includ- ing tentative identifications) of the 148 AzTEC-SHADES 1.1mm sources reported by Austermann et al. (2010), exploiting deep radio and 24 μm data complemented by methods based on 8 μm flux-density and red optical-infrared (i − K) colour. This unusually high identification rate can be attributed to the relatively bright millimetre- wavelength flux-density threshold, combined with the relatively deep supporting multi- frequency data now available in these two well-studied fields.We have further exploited the optical–mid-infrared–radio data to derive a ≃ 60% (≃ 75% including tentative identifications) complete redshift distribution for the AzTEC-SHADES sources, yield- ing a median redshift of z ≃ 2.2, with a high-redshift tail extending to at least z ≃ 4. Despite the larger area probed by the AzTEC survey relative to the original SCUBA SHADES imaging, the redshift distribution of the AzTEC sources is consistent with that displayed by the SCUBA sources, and reinforces tentative evidence that the red- shift distribution of mm/sub-mm sources in the Lockman Hole field is significantly different from that found in the SXDF/UDS field. Comparison with simulated sur- veys of similar scale extracted from semi-analytic models based on the Millennium simulation indicates that this is as expected if the mm/sub-mm sources are massive (M > 1011M⊙) star-forming galaxies tracing large-scale structures over scales of 10– 20Mpc. This confirms the importance of surveys covering several square degrees (as now underway with SCUBA2) to obtain representative samples of bright (sub)mm- selected galaxies. This work provides a foundation for the further exploitation of the Spitzer and Herschel data in the SHADES fields in the study of the stellar masses and specific star-formation rates of the most active star-forming galaxies in cosmic history.

Theoretical studies of non inductive current drive in compact toroids

Three non inductive current drive methods that can be applied to compact toroids are studied. The use of neutral beams to drive current in field reversed configurations and spheromaks is studied using a Monte Carlo code that includes a complete ionization package and follows the exact particle orbits in a self-consistent equilibrium calculated including the beam and plasma currents. Rotating magnetic fields are investigated as a current drive method for spherical tokamaks by employing a two dimensional model with fixed ions and massless electrons. The time evolution of the axial components of the magnetic field and vector potential is obtained by combining an Ohm's law that includes the Hall term with Maxwell's equations. The use of helicity injection to sustain a flux core spheromak is studied using the principle of minimum rate of energy dissipation. The Euler-Lagrange equations obtained using helicity balance as a constraint are solved to determine the current and magnetic field profiles of the relaxed states.6575Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Simulating JWST deep extragalactic imaging surveys and physical parameter recovery

We present a new prospective analysis of deep multi-band imaging with the James Webb Space Telescope (JWST). In this work, we investigate the recovery of high-redshift 5 > z > 12 galaxies through extensive image simulations of accepted JWST programs, including the Early Release Science in the EGS field and the Guaranteed Time Observations in the HUDF. We introduced complete samples of ∼300 000 galaxies with stellar masses of log(M∗/M⊙)> 6 and redshifts of 0 5 galaxy samples can be reduced to >0:01 arcmin-2 with a limited impact on galaxy completeness.We investigate multiple high-redshift galaxy selection techniques and find that the best compromise between completeness and purity at 5 < z < 10 using the full redshift posterior probability distributions. In the EGS field, the galaxy completeness remains higher than 50% at magnitudes mUV < 27:5 and at all redshifts, and the purity is maintained above 80 and 60% at z ≥ 7 and 10, respectively. The faint-end slope of the galaxy UV luminosity function is recovered with a precision of 0.1-0.25, and the cosmic star formation rate density within 0.1 dex. We argue in favor of additional observing programs covering larger areas to better constrain the bright end