Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1412.6694

Large-scale environment of $z\sim 5.7$ CIV absorption systems -II. Spectroscopy of Lyman-$α$ emitters

C. Gonzalo Díaz·Emma V. Ryan-Weber·Jeff Cooke·Yusei Koyama·Masami Ouchi
View original source ↗Read source document ↗Export metadata ↓

Abstract

The flow of baryons to and from a galaxy, which is fundamental for galaxy formation and evolution, can be studied with galaxy-metal absorption system pairs. Our search for galaxies around CIV absorption systems at $z\sim5.7$ showed an excess of photometric Lyman-$α$ emitter (LAE) candidates in the fields J1030+0524 and J1137+3549. Here we present spectroscopic follow-up of 33 LAEs in both fields. In the first field, three out of the five LAEs within 10$h^{{-}1}$ projected comoving Mpc from the CIV system are within $\pm500$ km s$^{{-}1}$ from the absorption at $z_{\text{CIV}}=5.7242\pm0.0001$. The closest candidate (LAE 103027+052419) is robustly confirmed at $212.8^{+14}_{-0.4}h^{-1}$ physical kpc from the CIV system. In the second field, the LAE sample is selected at a lower redshift ($Δz\sim0.04$) than the CIV absorption system as a result of the filter transmission and, thus, do not trace its environment. The observed properties of LAE 103027+052419 indicate that it is near the high-mass end of the LAE distribution, probably having a large HI column density and large-scale outflows. Therefore, our results suggest that the CIV system is likely produced by a star-forming galaxy which has been injecting metals into the intergalactic medium since $z>6$. Thus, the CIV system is either produced by LAE 103027+052419, implying that outflows can enrich larger volumes at $z>6$ than at $z\sim3.5$, or an undetected dwarf galaxy. In either case, CIV systems like this one trace the ionized intergalactic medium at the end of cosmic hydrogen reionization and may trace the sources of the ionizing flux density.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

C. Gonzalo Díaz, Emma V. Ryan-Weber, Jeff Cooke, Yusei Koyama, Masami Ouchi. 2015-02-09. Large-scale environment of $z\sim 5.7$ CIV absorption systems -II. Spectroscopy of Lyman-$α$ emitters. https://doi.org/10.1093/mnras%2Fstu2738

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

LMC-induced Perturbations in the Milky Way Halo:I. HaloDance Simulation Suite and Observational Forecasts

The gravitational interaction between the Milky Way (MW) and the Large Magellanic Cloud (LMC) perturbs the MW halo's density and kinematics, encoding information about both galaxies' masses and structures. We present a suite of 2,848 high-resolution ($10^7$ particles) N-body simulations that systematically vary the mass and shape of both galaxies' haloes. We model how the mean velocities and velocity dispersions of halo stars (30--120 kpc) depend on system parameters, and forecast constraints achievable with current and future observations. Assuming Gaia DR3-level astrometry, 20 km/s radial velocity precision, 10% distance precision, and a sample of $\sim$4,000 RR Lyrae stars, we achieve 1$σ$ uncertainties of $0.11 \times 10^{12} M_\odot$ in MW mass, $2.33 \times 10^{10} M_\odot$ in LMC mass, 2.38 in halo concentration ($c$), and 0.06 in halo flattening ($q$). These correspond to fractional uncertainties of 11%, 16%, 25%, and 6% respectively, relative to fiducial values. Improved Gaia proper motions (DR5) yield modest gains (up to 14%), while adding radial velocities improves constraints by up to 60% relative to using Gaia astrometry alone. Doubling the sample size to $\sim$8,000 stars yields an additional 30% improvement, whereas reducing distance uncertainties has minimal impact ($\le$10%). Mean velocities trace LMC-induced perturbations, while velocity dispersions constrain MW halo properties, jointly breaking degeneracies. Our results demonstrate that combining Gaia astrometry with large spectroscopic surveys will enable precise characterization of the MW-LMC system. This methodology paper establishes the framework for interpreting observations; future work will apply these tools to existing spectroscopic datasets. The full simulation suite, HaloDance, will be made publicly available at: https://github.com/Yanjun-Sheng/HaloDance.

astro-ph.GA↗
arXiv2026

Gravitational Waves from Cosmic Dawn: Tracing Cosmic Black Hole Binaries with ET, LGWA, and LISA

Next-generation detectors, such as LISA, LGWA, and ET, will for the first time probe the high redshift Universe, offering unique insight into the birth, growth, and dynamics of the first black holes (BHs) during their earliest stages of formation. We aim to predict merger rates and gravitational wave (GW) signatures of "cosmic" binary BHs forming as a result of galaxy mergers at $z\geq 4$. We investigate how BH seeding, accretion physics, and dynamical delays affect their properties and detectability across cosmic epochs. We used the semi-analytic model Cosmic Archaeology Tool (CAT) to trace the evolution and delayed mergers, driven by dynamical friction, of BH binaries formed from light, medium-weight, and heavy seeds under Eddington-limited (EL) and super-Eddington (SE) accretion prescriptions. We employed the GWFish package to evaluate their GW signals and detectability by LISA, LGWA, and ET. Our results show the impact of BH accretion and seeding prescriptions on the properties and distribution of detectable sources. In the EL model, the detected populations are dominated by nearly equal-mass binaries ($\tilde{q} = 0.7$). In contrast, SE growth leads to lower mass ratios for LISA detections ($\tilde{q} \sim 0.2$) and medium ratios for ET and LGWA ($\tilde{q} \sim 0.4$ and $0.3$, respectively). We present the total detection rates predicted under the two accretion scenarios. The SE model allows BHs to grow faster, transferring a significant fraction of detectable systems from the ET band to the LISA band, compared to the EL model. As a result, the predicted LISA detection rate increases from ~ 32 yr$^{-1}$ in the EL case to ~ 64 yr$^{-1}$ in the SE scenario, and the ET detection rate reduces from ~ 64 yr$^{-1}$ in the EL model to only ~ 4 yr$^{-1}$ in the SE scenario. In both scenarios, LGWA yields comparable detection rates (~ 21 yr$^{-1}$ in EL and ~ 12 yr$^{-1}$ in SE).

astro-ph.GA↗
arXiv2026

The Radio-FIR Correlation in the Context of Deep Radio Source Counts

Increasingly deep, confusion-limited radio surveys have pushed direct radio source-count measurements down to tens of $μ$Jy at 1.4 GHz. Confusion-noise P(D) analyses extend the statistical counts to below $1\,\mathrm{μJy}$. Radio source counts have allowed for constraints on the radio-derived star formation rate density (SFRD) history through models of the backwards evolution of the local radio luminosity function, using the radio-FIR correlation, $q \propto \log(L_{\mathrm{FIR}}/L_{1.4})$, to convert radio luminosities to FIR luminosities and hence star-formation rates. Recent deep radio source counts from MeerKAT suggest a potential tension in the SFRD history between radio and UV/IR measurements at $1\lesssim z\lesssim 2$. This corresponds to a $\gtrsim 3σ$ discrepancy between the predicted and measured source counts near the star forming galaxy source count $S^2n(S)$ peak of ${\sim}30\,\mathrm{μJy}$ under both a pure luminosity (PLE) and combined luminosity and density evolution (LADE). We consider what the requirement of agreement between radio source counts and the observed UV/IR SFRD indicates about the redshift evolution of the radio-FIR correlation and its intrinsic scatter out to $z=3$. We introduce a radio-luminosity based parameterization to $q_{\mathrm{FIR}}(z)$ based on changing thermal radio fractions alone that agrees with the observed stellar-mass dependent $q_{\mathrm{FIR}}(z)$ better than a non-evolving or decreasing $q_{\mathrm{FIR}}(z)$. Despite this, we find that a decreasing $q_{\mathrm{FIR}}(z)$ at fixed radio luminosity provides better agreement between source counts and the observed SFRD, while a $q_{\mathrm{FIR}}(z)$ that breaks down due to cosmic ray losses requires an intrinsic scatter up to $σ_q\approx 0.3\,\mathrm{dex}$.

astro-ph.GA↗