分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The relation between the integrated thermal Sunyaev-Zeldovich (tSZ) $y$-decrement versus halo mass ($Y$--$M$) can potentially constrain galaxy formation models, if theoretical and observational systematics can be properly assessed. We investigate the $Y$--$M$ relation in the SIMBA and IllustrisTNG-100 cosmological hydrodynamic simulations, quantifying the effects of feedback, line-of-sight projection, and beam convolution. We find that SIMBA's AGN jet feedback generates strong deviations from self-similar expectations for the $Y$--$M$ relation, especially at $M_{500}<10^{13}M_{\odot}$. In SIMBA, this is driven by suppressed in-halo $y$ contributions owing to lowered halo baryon fractions. IllustrisTNG results more closely resemble SIMBA without jets. Projections of line-of-sight structures weaken these model differences slightly, but they remain significant -- particularly at group and lower halo masses. In contrast, beam smearing at $\textit{Planck}$ resolution makes the models indistinguishable, and both models appear to agree well with $\textit{Planck}$ data down to the lowest masses probed. We show that the arcminute resolution expected from forthcoming facilities would retain the differences between model predictions, and thereby provide strong constraints on AGN feedback.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the nature of the low-redshift CGM in the Simba cosmological simulations as traced by ultraviolet absorption lines around galaxies in bins of stellar mass ($M_\star>10^{10}M_\odot$) for star-forming, green valley and quenched galaxies at impact parameters $r_\perp\leq 1.25r_{200}$. We generate synthetic spectra for HI, MgII, CII, SiIII, CIV, and OVI, fit Voigt profiles to obtain line properties, and estimate the density, temperature, and metallicity of the absorbing gas. We find that CGM absorbers are most abundant around star forming galaxies with $M_\star < 10^{11}M_\odot$, while the abundance of green valley galaxies show similar behaviour to those of quenched galaxies, suggesting that the CGM "quenches" before star formation ceases. HI absorbing gas exists across a broad range of cosmic phases (condensed gas, diffuse gas, hot halo gas and Warm-Hot Intergalactic Medium), while essentially all low-ionisation metal absorption arises from condensed gas. OVI absorbers are split between hot halo gas and the WHIM. The fraction of collisionally ionised CGM absorbers is $\sim 25-55\%$ for CIV and $\sim 80-95\%$ for OVI, depending on stellar mass and impact parameter. In general, the highest column density absorption features for each ion arise from dense gas. Satellite gas, defined as that within $10r_{1/2,\star},$ contributes $\sim 3\%$ of overall HI absorption but $\sim 30\%$ of MgII absorption, with the fraction from satellites decreasing with increasing ion excitation energy.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shoko Jin
Scott C. Trager
Gavin B. Dalton
J. Alfonso L. Aguerri
J. E. Drew
Jesús Falcón-Barroso
Boris T. Gänsicke
Vanessa Hill
Angela Iovino
Matthew M. Pieri
Bianca M. Poggianti
D. J. B. Smith
Antonella Vallenari
Don Carlos Abrams
David S. Aguado
Teresa Antoja
Alfonso Aragón-Salamanca
Yago Ascasibar
Carine Babusiaux
Marc Balcells
摘要： WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges at $R\sim20\,000$. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for $\sim$3 million stars and detailed abundances for $\sim1.5$ million brighter field and open-cluster stars; (ii) survey $\sim0.4$ million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey $\sim400$ neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in $z1$ million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at $z>2$. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator.
点击量
待评议
点击量
下载量
评论
