The CGM and IGM at z∼\sim5: metal budget and physical connection

We present further results of a survey for absorption line systems in the spectra of four high redshift quasars (5.79 $\le$ z$_{\textrm{em}}$ $\le$ 6.13) obtained with the ESO Very Large Telescope X-Shooter. We identify 36 $\textrm{CIV}$ and 7 $\textrm{SiIV}$ systems with a $\ge$ 5$\sigma$ significance. The highest redshift $\textrm{CIV}$ and $\textrm{SiIV}$ absorbers identified in this work are at z = 5.80738 $\pm$ 0.00017 and z = 5.77495 $\pm$ 0.00038, respectively. We compute the comoving mass density of $\textrm{SiIV}$ ($\Omega_{\textrm{SiIV}}$) and find that it evolves from $\Omega_{\textrm{SiIV}}$ = 4.3$^{+2.1}_{-2.1}$ $\times$10$^{-9}$ at = 5.05 to $\Omega_{\textrm{SiIV}}$ = 1.4$^{+0.6}_{-0.4}$ $\times$10$^{-9}$ at = 5.66. We also measure $\Omega_{\textrm{CIV}}$ = 1.6$^{+0.4}_{-0.1}$ $\times$10$^{-8}$ at = 4.77 and $\Omega_{\textrm{CIV}}$ = 3.4$^{+1.6}_{-1.1}$ $\times$10$^{-9}$ at = 5.66. We classify our $\textrm{CIV}$ absorber population by the presence of associated $\textit{low}$ and/or $\textit{high ionisation}$ systems and compute their velocity width ($\Delta$v$_{90}$). We find that all $\textrm{CIV}$ systems with $\Delta$v$_{90}$ > 200 kms$^{-1}$ have associated $\textit{low ionisation}$ systems. We investigate two such systems, separated by 550 physical kpc along a line of sight, and find it likely that they are both tracing a multi-phase medium where hot and cold gas is mixing at the interface between the CGM and IGM. We further discuss the \textrm{MgII} systems presented in a previous work and we identify 5 $\textrm{SiII}$, 10 $\textrm{AlII}$, 12 $\textrm{FeII}$, 1 $\textrm{CII}$, 7 $\textrm{MgI}$ and 1 $\textrm{CaII}$ associated transitions. We compute the respective comoving mass densities in the redshift range 2 to 6, as allowed by the wavelength coverage.Comment: Accepted for publication in MNRAS 22 pages, 19 figures, 6 table

Network failure: Biotechnology firms, clusters and collaborations far from the world superclusters

This article traces the trajectory of biotechnology firms, clusters and collaborations in Australia between 2003 and 2014. Combining descriptive analyses, network visualizations and statistical modelling of longitudinal data collected from multiple sources, we investigate Australian firms’ ability to overcome the three challenges characterizing biotechnology: first, accessing new knowledge and intellectual property; second, raising early-stage funding for timely product development; and third, bringing products to market. Like biotechnology firms worldwide, Australian firms adopt a network approach to success, relying on different types of collaborative ties with diverse partners to access complementary resources and facilitate learning and innovation. The aspiration here is a virtuous cycle, where networks promote innovation and innovation promotes networks, as occurs in the world superclusters. In contrast, our analyses show that the collaborations of Australian biotechnology firms produce not so much a virtuous cycle, as a dead end. Specifically, local collaborations with public research organizations generate network effects in meeting the challenges of new knowledge and early-stage funding, but do not extend to the challenge of bringing products to market. We link this 'network failure' to the limitations of public research organizations as anchor tenants with the capability to catalyze collaborations with distant partner organizations directed towards commercialization, in particular giant multinational pharmaceutical corporations. Our study enriches the substantial literature on networked innovation, which is biased towards celebrating the benefits of networks and collaborations for innovation and performance, particularly in biotechnology

UVUDF: UV Luminosity Functions at the Cosmic High Noon

We present the rest-1500 Å UV luminosity functions (LF) for star-forming galaxies during the cosmic high noon—the peak of cosmic star formation rate at 1.5 < z < 3. We use deep NUV imaging data obtained as part of the Hubble Ultra-Violet Ultra Deep Field (UVUDF) program, along with existing deep optical and NIR coverage on the HUDF. We select F225W, F275W, and F336W dropout samples using the Lyman break technique, along with samples in the corresponding redshift ranges selected using photometric redshifts, and measure the rest-frame UV LF at z ~ 1.7, 2.2, 3.0, respectively, using the modified maximum likelihood estimator. We perform simulations to quantify the survey and sample incompleteness for the UVUDF samples to correct the effective volume calculations for the LF. We select galaxies down to M_(UV) = -15.9, -16.3, -16.8 and fit a faint-end slope of α = -1.20^(+0.10)_(-0.13), -1.32^(+0.10)_(-0.14), -1.39^(+0.08)_(-0.12) at 1.4 < z < 1.9, 1.8 < z < 2.6, and 2.4 < z < 3.6, respectively. We compare the star formation properties of z ~ 2 galaxies from these UV observations with results from Hα and UV+IR observations. We find a lack of high-SFR sources in the UV LF compared to the Hα and UV+IR, likely due to dusty SFGs not being properly accounted for by the generic IRX-β relation used to correct for dust. We compute a volume-averaged UV-to-Hα ratio by abundance matching the rest-frame UV LF and Hα LF. We find an increasing UV-to-Hα ratio toward low-mass galaxies (M_∗ ≾ 5 x 10^9 M_⊙). We conclude that this could be due to a larger contribution from starbursting galaxies compared to the high-mass end

The Lyman Continuum Escape Fraction of Star-forming Galaxies at 2.4≲z≲3.72.4\lesssim z\lesssim3.7 from UVCANDELS

The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of primary Wide-Field Camera 3 Ultraviolet and Visible light F275W imaging with coordinated parallel Advanced Camera for Surveys F435W imaging, on four of the five premier extragalactic survey fields: GOODS-N, GOODS-S, EGS, and COSMOS. We introduce this survey by presenting a thorough search for galaxies at $z\gtrsim2.4$ that leak significant Lyman continuum (LyC) radiation, as well as a stringent constraint on the LyC escape fraction ($f_{\rm esc}$) from stacking the UV images of a population of star-forming galaxies with secure redshifts. Our extensive search for LyC emission and stacking analysis benefit from the catalogs of high-quality spectroscopic redshifts compiled from archival ground-based data and HST slitless spectroscopy, carefully vetted by dedicated visual inspection efforts. We report a sample of five galaxies as individual LyC leaker candidates, showing $f_{\rm esc}^{\rm rel}\gtrsim60\%$ estimated using detailed Monte Carlo analysis of intergalactic medium attenuation. We develop a robust stacking method to apply to five samples of in total 85 non-detection galaxies in the redshift range of $z\in[2.4,3.7]$. Most stacks give tight 2-$\sigma$ upper limits below $f_{\rm esc}^{\rm rel}<6\%$. A stack for a subset of 32 emission-line galaxies shows tentative LyC leakage detected at 2.9-$\sigma$, indicating $f_{\rm esc}^{\rm rel}=5.7\%$ at $z\sim2.65$, supporting the key role of such galaxies in contributing to the cosmic reionization and maintaining the UV ionization background. These new F275W and F435W imaging mosaics from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes.Comment: 33 pages, 21 figures, and 5 tables. Resubmitted after addressing the referee repor

First demonstration of early warning gravitational wave alerts

International audienceGravitational-wave observations became commonplace in Advanced LIGO-Virgo’s recently concluded third observing run. 56 nonretracted candidates were identified and publicly announced in near real time. Gravitational waves from binary neutron star mergers, however, remain of special interest since they can be precursors to high-energy astrophysical phenomena like γ-ray bursts and kilonovae. While late-time electromagnetic emissions provide important information about the astrophysical processes within, the prompt emission along with gravitational waves uniquely reveals the extreme matter and gravity during—and in the seconds following—merger. Rapid communication of source location and properties from the gravitational-wave data is crucial to facilitate multimessenger follow-up of such sources. This is especially enabled if the partner facilities are forewarned via an early warning (pre-merger) alert. Here we describe the commissioning and performance of such a low-latency infrastructure within LIGO-Virgo. We present results from an end-to-end mock data challenge that detects binary neutron star mergers and alerts partner facilities before merger. We set expectations for these alerts in future observing runs