Monthly Notices of the Royal Astronomical Society

Berg, Trystyn A M; Hayes, Christian R; Cristiani, Stefano; McConnachie, Alan; Robertson, J Gordon; Sestito, Federico; Simpson, Chris; Waller, Fletcher; Chin, Timothy; Densmore, Adam; Diaz, Ruben J; Edgar, Michael L; Fuentes Lettura, Javier; Gómez-Jiménez, Manuel; Kalari, Venu M; Lawrence, Jon; Margheim, Steven; Pazder, John; Ruiz-Carmona, Roque; Salinas, Ricardo; Silva, Karleyne M G; Silversides, Katherine; Venn, Kim A

doi: 10.1093/mnras/stae1033pmid: N/A

ABSTRACTThe Gemini High-resolution Optical SpecTrograph (GHOST) is a new Echelle spectrograph available on the Gemini-South telescope as of Semester 2024A. We present the first high-resolution spectrum of the quasar J1449−1227 (redshift zem = 3.27) using data taken during the commissioning of GHOST. The observed quasar hosts an intervening iron-poor {[Fe/H] = −2.5} damped Lyman α system (DLA) at redshift z = 2.904. Taking advantage of the high spectral resolving power of GHOST (R ≈ 55 000), we are able to accurately model the metal absorption lines of the metal-poor DLA and find a supersolar [Si/Fe], suggesting that the DLA gas is in an early stage of chemical enrichment. Using simple ionization models, we find that the large range in the C iv/Si iv column density ratio of individual components within the DLA’s high-ionization absorption profile can be reproduced by several metal-poor Lyman limit systems surrounding the low-ionization gas of the DLA. It is possible that this metal-poor DLA resides within a complex system of metal-poor galaxies or filaments with inflowing gas. The high spectral resolution, wavelength coverage, and sensitivity of GHOST make it an ideal spectrograph for characterizing the chemistry and kinematics of quasar absorption lines.

Yang, Yuangui; Wang, Shuang

doi: 10.1093/mnras/stae1352pmid: N/A

ABSTRACTWe reported the light curves (LCs) and orbital period variations of four short-period eclipsing binaries in the Southern hemisphere. From short-cadence time-series observations of the TESS, the intrinsic light changes rapidly with time. Δmmax and Δmmin exhibit random wave-like variations or quasi-periodicities. We deduced 14 sets of photometric solutions from the truncated LCs using the W-D programme. The results imply that V757 Cen and BC Gru are near-contact binaries, whose one or two components almost fill the Roche lobes with $f\gt 98{{\ \rm per\ cent}}$. Meanwhile, V535 Ara and AQ Tuc are A-subtype contact binaries. The asymmetric LCs were modelled by a cool spot assumed on a more massive component, which was used to track the stellar longitudes of star-spots. Based on all available eclipsing times (ETs), including 1495 ones from TESS LCs, the orbital period variations of four binaries were analysed. The (O − C) curves are coincidentally demonstrated by the light-time effect via the presence of the third bodies. The modulation periods approximate to 50 ∼ 60 yr. In the coplanar orbit with the central binaries, the third companions’ masses are 0.105 M⊙ for V757 Cen, 0.340 M⊙ for BC Gru, 0.238 M⊙ for V535 Ara, and 0.343 M⊙ for AQ Tuc, whose systems are stable according to Harrington’s criterion. Therefore, the four short-period eclipsing binaries, V757 Cen, BC Gru, V535 Ara, and AQ Tuc are hierarchical triple stellar systems.

Gebek, Andrea; Trčka, Ana; Baes, Maarten; Martorano, Marco; Pillepich, Annalisa; Kapoor, Anand Utsav; Nersesian, Angelos; van der Wel, Arjen

doi: 10.1093/mnras/stae1377pmid: N/A

ABSTRACTWe apply the 3D dust radiative transfer code skirt to the low-redshift (z ≤ 0.1) galaxy population in the TNG100 cosmological simulation, the fiducial run of the IllustrisTNG project. We compute global fluxes and spectral energy distributions (SEDs) from the far-ultraviolet to the submillimetre for $\approx 60\, 000$ galaxies, with the same post-processing methodology that was previously applied to the TNG50 simulation. We verify that TNG100 reproduces observational luminosity functions at low redshifts to excellent precision, unlike TNG50. Additionally, we test the realism of our TNG100 plus skirt fluxes by comparing various flux and colour relations to data from the GAMA survey. TNG100 broadly reproduces the observed distributions, but we predict ultraviolet colours that are too blue by $\approx 0.4\, \mathrm{mag}$, possibly related to the extinction in the star-forming regions subgrid model not being selective enough. Furthermore, we find that the simulated galaxies exhibit mid-infrared fluxes elevated by up to $\approx 0.5\, \mathrm{mag}$ that we attribute to overly effective stochastic heating of the diffuse dust. All synthetic broad-band fluxes and SEDs are made publicly available in three orientations and four apertures, and can readily be used to study TNG100 galaxies in a mock observational fashion.

Rowntree, Aaron R; Singh, Ankit; Vincenzo, Fiorenzo; Gibson, Brad K; Gouin, Céline; Galárraga-Espinosa, Daniela; Lee, Jaehyun; Kim, Juhan; Laigle, Clotilde; Park, Changbom; Pichon, Christophe; Few, Gareth; Hong, Sungwook E; Kim, Yonghwi

doi: 10.1093/mnras/stae1384pmid: N/A

ABSTRACTMetallicity offers a unique window into the baryonic history of the cosmos, being instrumental in probing evolutionary processes in galaxies between different cosmic environments. We aim to quantify the contribution of these environments to the scatter in the mass–metallicity relation (MZR) of galaxies. By analysing the galaxy distribution within the cosmic skeleton of the Horizon Run 5 cosmological hydrodynamical simulation at redshift z = 0.625, computed using a careful calibration of the T-ReX filament finder, we identify galaxies within three main environments: nodes, filaments, and voids. We also classify galaxies based on the dynamical state of the clusters and the length of the filaments in which they reside. We find that the cosmic environment significantly contributes to the scatter in the MZR; in particular, both the gas metallicity and its average relative standard deviation increase when considering denser large-scale environments. The difference in the average metallicity between galaxies within relaxed and unrelaxed clusters is ≈0.1dex, with both populations displaying positive residuals, δZg, from the averaged MZR. Moreover, the difference in metallicity between node and void galaxies accounts for $\approx 0.14 \, \text{dex}$ in the scatter of the MZR at stellar mass $M_{\star } \approx 10^{9.35}\, \text{M}_{\odot }$. Finally, both the average [O/Fe] in the gas and the galaxy gas fraction decrease when moving to higher large-scale densities in the simulation, suggesting that the cores of cosmic environments host – on average – older and more massive galaxies, whose enrichment is affected by a larger number of Type Ia Supernova events.

Boshkayev, K; Konysbayev, T; Kurmanov, Ye; Muccino, M; Quevedo, H

doi: 10.1093/mnras/stae1388pmid: N/A

ABSTRACTQuasi-periodic oscillation (QPOs) analysis is important for understanding the dynamical behaviour of many astrophysical objects during transient events such as gamma-ray bursts, solar flares, magnetar flares, and fast radio bursts. In this paper, we analyse QPO data in low-mass X-ray binary (LMXB) systems, using the Lense-Thirring, Kerr, and approximate Zipoy-Voorhees metrics. We demonstrate that the inclusion of spin and quadrupole parameters modifies the well-established results for the fundamental frequencies in the Schwarzschild space–time. We interpret the QPO data within the framework of the standard relativistic precession model, allowing us to infer the values of the mass, spin, and quadrupole parameters of neutron stars in LMXBs. We explore recent QPO data sets from eight distinct LMXBs, assess their optimal parameters, and compare our findings with results in the existing literature. Finally, we discuss the astrophysical implications of our findings.

Lu, Anan; Haggard, Daryl; Bureau, Martin; Gensior, Jindra; Jeffreson, Sarah; Robert, Carmelle; Williams, Thomas G; Liang, Fu-Heng; Choi, Woorak; Davis, Timothy A; Babic, Sara; Boyce, Hope; Cheung, Benjamin; Drissen, Laurent; Elford, Jacob S; Liu, Lijie; Martin, Thomas; Rhea, Carter; Rousseau-Nepton, Laurie; Ruffa, Ilaria

Zhang, Xiao-Li; Zou, Ze-Cheng; Huang, Yong-Feng; Gao, Hao-Xuan; Wang, Pei; Cui, Lang; Liu, Xiang

doi: 10.1093/mnras/stae1400pmid: N/A

ABSTRACTAccording to the strange quark matter hypothesis, strange planets may exist, which are planetary mass objects composed of almost equal numbers of up, down, and strange quarks. A strange planet can revolve around its host strange star in a very close-in orbit. When it finally merges with the host, strong gravitational wave emissions will be generated. Here, the gravitational waveforms are derived for the merging process, taking into account the effects of the strange star’s magnetic field on the dynamics. Effects of the inclination angle are also considered. Templates of the gravitational waveforms are derived. It is found that the magnetic interactions significantly speed up the merging process. Coalescence events of such strange planetary systems occurring in our Galaxy as well as in local galaxies can be effectively detected by current and future gravitational experiments, which may hopefully provide a new method to test the strange quark matter hypothesis and probe the magnetic field of compact stars.

Boehnhardt, Hermann; Lara, Luisa; Gray, Zuri; Bagnulo, Stefano

doi: 10.1093/mnras/stae1412pmid: N/A

ABSTRACTWe present results on the global activity of comet 67P/Churyumov–Gerasimenko (67P), the ROSETTA target, during its first perihelion passage after the mission and after an encounter with planet Jupiter. 67P was observed by broad-band filter imaging at 33 epochs during 2021 May 21 to 2022 June 1. The mean radial flux profiles suggest that ‘equilibrium’ conditions for the dust flow in the coma existed from around perihelion until about 100 d thereafter. We propose a scenario for the smaller and larger radial exponents, measured before and after the ‘equilibrium’ phase. Four coma fans with possible source regions at +40°, –10°, –50°, and –70° latitude on the nucleus are identified. The three fans at southern latitudes may be identical with fan sources seen during post-perihelion in 2015–2016. The rotation axis of 67P may not have changed at all or at least not much (<5°) from the orientation measured during the Rosetta mission at the comet. The dust streamers in the coma originated from observed coma fans, containing mostly dust emitted within days to weeks before observation. Two dust streamers, a long- and a short-lasting one, contained heavy dust grains from emission periods hundreds of days before perihelion. Similar emission periods are obtained for the dust seen in the tail region of the comet. Similarities and differences in the dust activity during the recent apparition with that of the Rosetta mission at the comet are found.

Mao, Lisheng; Zhang, Xuemei

doi: 10.1093/mnras/stae1380pmid: N/A

ABSTRACTThe detection of quasi-periodic oscillations (QPOs) in blazar light curves is crucial for understanding their nature and fundamental physical processes. PKS J2156−0037 (z = 0.495), a blazar monitored by the Owens Valley Radio Observatory (OVRO) 40-m radio telescope, is the subject of this study. We searched for the presence of QPOs in the publicly available 15 GHz light curve of PKS J2156−0037, spanning 2008 January to 2020 January. We employed four well-established methods (the Jurkevich method, the generalized Lomb–Scargle periodogram, the weighted wavelet Z-transform, and the redfit method) that offer complementary strengths for robust periodicity detection. A consistent and statistically significant QPO signal was detected with a periodicity of around 611 d (at least 4.26σ local significance) and a global significance exceeding 99.83 per cent (or 2.92σ) based on Monte Carlo simulations with 105 simulated light curves (assuming underlying red-noise processes). This is the first reported detection of such a variability feature in this object. The possible physical mechanisms responsible for radio QPOs in blazars are discussed briefly.

Zhao, Q C; Li, H C; Tao, L; Feng, H; Zhang, S N; Walter, R; Ge, M Y; Tong, H; Ji, L; Zhang, L; Qu, J L; Huang, Y; Ma, X; Zhang, S; Yin, Q Q; Yin, H X; Ma, R C; Zhao, S J; Li, P P; Yang, Z X; Liu, H X; Yu, W; Huang, Y M; Li, Z X; Li, Y J;