为了研究恒星源是否可以解释由5<z<6.4类星体样品的mm/sub-mm观测推断的>10^8 Msun尘埃质量,我们发展了一个化学演化模型,该模型遵循金属和尘埃对恒星特征寿命的演化,考虑到尘埃的破坏机制。使用恒星尘埃网格作为初始质量和金属丰度的函数,40 Msun和0-1 Zsun的情况下,我们发现在高红移下AGB星在宇宙尘埃演化中的作用可能被忽略了.我们将含尘埃的化学演化模型应用于z=6.4的最远类星体SDSS J1148+ 5251的宿主星系.(i)Li et al.在数值模拟中获得的恒星形成历史。(2007)预测在z= 6.4时已经形成了一个大的恒星核球,(ii)如果远红外区的大部分光度是由年轻恒星产生的,那么恒星的形成速率为1000 Msun/yr,这与观测结果一致。AGB尘埃的贡献很大(80%)。当采用恒定的恒星形成率时,AGB尘埃的贡献减少到50%,但形成的尘埃总质量是一个小的因素2。两个模型预测的快速富集的ISM与金属和相对温和的碳丰度的演变,与观测的限制。这支持了恒星源可以解释观测到的尘埃的观点,但也表明AGB星对尘埃产生的贡献不能被忽视,即使是在目前观测到的最极端的红移下。
英文摘要:
With the aim of investigating whether stellar sources can account for the >10^8 Msun dust masses inferred from mm/sub-mm observations of samples of 5<z<6.4 quasars,we develop a chemical evolution model which follows the evolution of metals and dust on the stellar characteristic lifetimes, taking into account dust destruction mechanisms.Using a grid of stellar dust yields as a function of the initial mass and metallicity over the range 1-40 Msun and 0-1 Zsun,we show that the role of AGB stars in cosmic dust evolution at high redshift might have been over-looked.We apply the chemical evolution model with dust to the host galaxy of the most distant quasar at z=6.4, SDSS J1148+5251.Given the current uncertainties on the star formation history of the host galaxy, we have considered two models: (i) a star formation history obtained in a numerical simulation by Li et al.(2007) which predicts that a large stellar bulge is already formed at z=6.4,and (ii) a constant star formation rate of 1000 Msun/yr, as suggested by the observations if most of the FIR luminosity is due to young stars.The total mass of dust predicted at z=6.4 by the first model is 2x10^8Msun,within the range of values inferred by observations,with a substantial contribution (80%) of AGB-dust.When a constant star formation rate is adopted,the contribution of AGB-dust decreases to 50% but the total mass of dust formed is a factor 2 smaller.Both models predict a rapid enrichment of the ISM with metals and a relatively mild evolution of the carbon abundance,in agreement with observational constraints. This supports the idea that stellar sources can account for the dust observed but show that the contribution of AGB stars to dust production cannot be neglected, even at the most extreme redshifts currently accessible to observations.
The Origin of Dust in the Early Universe: Probing the Star Formation History of Galaxies by their Dust Content
对于在高红移(z = 6.4)类星体J1148+5251中观测到的~ 4 \times 10^8 M \odot尘埃的起源,提出了两种不同的方案。第一个假设是这个星系比宇宙在那个时期的年龄年轻得多,所以只有超新星(SNe)才能产生这种尘埃。第二种情况假设银河系的年龄要大得多,因此尘埃可能是在质量较低的渐近巨星分支(AGB)恒星中形成的。提出了新的积分解决方案的化学演化的金属和尘埃在星系中,我们提供了一个关键的评估这两种情况下,和观测结果,可以区分两者。我们表明,AGB恒星可以产生推断质量的尘埃在这个对象中,然而,最终质量的幸存尘埃取决于星系的恒星形成历史(SFH)。一般来说,超新星不能产生观测到的尘埃量,除非平均SN事件在其喷出物中产生超过~ 1 M \odot的尘埃。然而,可以构建特殊的SFHS,其中SNe可以产生推断的尘埃质量,合理的平均尘埃产量约为0.15 M \odot。这两种情况提出了星系光谱能量分布的不同起源,不同的恒星形成效率和恒星质量,以及J1148+5251型超亮红外(IR)天体的不同共动数密度。诊断中红外精细结构线的检测,以及确定这些物体的共动数密度的更完整的调查可以区分这两种情况。
How dead are dead galaxies? Mid-Infrared fluxes of quiescent galaxies at redshift 0.3 < z < 2.5: implications for star formation rates and dust heating
Herschel-ATLAS: Properties of dusty massive galaxies at low and high redshifts
我们提出了一个比较的物理性质的休息帧$250μ$ m选定的样本的大规模,尘埃星系从$0<z<5.3$。我们的样本包括文献中的29个高红移亚毫米星系(SMG)和赫歇尔-阿特拉斯的$z<0.5$上的843个尘埃星系,这些星系被选择为与SMG具有相似的恒星质量。$z>1$ SMG的平均SFR为$390^{+80}_{-70}\,$ M $_\odot$ yr $^{-1}$,是在恒星质量上与SMG匹配的低红移样本的SFR($=3.3\pm{0.2}$ M $_\odot$ yr $^{-1}$)的120倍。与低红移尘埃星系的$(1.6\pm0.1)\times{10}^8\,$ M $_\odot$相比,SMG拥有大量的尘埃($1.2^{+0.3}_{-0.2}\times{10}^9\,$ M $_\odot$)。在低红移的尘埃光度占主导地位的弥漫ISM,而大部分的尘埃光度的SMG起源于恒星形成区。在相同的尘埃质量的SMG是向更高的SFR相比,低红移的H-ATLAS星系偏移。这不仅是因为SMG中的气体比例较高,而且还因为它们正在经历一种更有效的恒星形成模式,这与它们的爆发性恒星形成历史相一致。SMG和低红移星系之间的SFR偏移与CO研究中发现的相似,这表明尘埃质量和CO一样是分子气体的良好示踪剂。
We post-process galaxies in the IllustrisTNG simulations with SKIRT radiative transfer calculations to make predictions for the rest-frame near-infrared (NIR) and far-infrared (FIR) properties of galaxies at $z\geq 4$. The rest-frame $K$- and $z$-band galaxy luminosity functions from TNG are overall consistent with observations, despite a $\sim 0.5\,\mathrm{dex}$ underprediction at $z=4$ for $M_{\rm K}\lesssim -25$ and $M_{\rm z}\lesssim -24$. Predictions for the JWST MIRI observed galaxy luminosity functions and number counts are given. Based on theoretical estimations, we show that the next-…
We explore the possibility of detecting the first galaxies with the next generation Origins Space Telescope (OST) by applying an analytical model of primordial dust emission. By analysing source densities as a function of redshift (z), and considering deep-field exposures with the Origins Survey Spectrometer, we estimate that the redshift horizon for detecting one individual source would be above z~7 for systems with dust-to-metal ratios higher than those expected for typical primeval galaxies. On the other hand, if confusion limits could be overcome, the Far-infrared Imager and Polarimeter wo…
We report Atacama Large Millimetre Array (ALMA) observations of four high-redshift dusty star-forming galaxy candidates selected from far-Infrared (FIR)/submm observations in the COSMOS field. We securely detect all galaxies in the continuum and spectroscopically confirm them at z=3.62--5.85 using ALMA 3mm line scans, detecting multiple CO and/or [CI] transitions. This includes the most distant dusty galaxy currently known in the COSMOS field, ID85001929 at z=5.847. These redshifts are lower than we had expected as these galaxies have substantially colder dust temperatures (i.e., their SEDs pe…
We compare the properties of stellar populations of model galaxies from the Cosmic Reionization On Computers (CROC) project with the exiting UV and IR data. Since CROC simulations do not follow cosmic dust directly, we adopt two variants of the dust-follows-metals ansatz to populate model galaxies with dust. Using the dust radiative transfer code Hyperion, we compute synthetic stellar spectra, UV continuum slopes, and IR fluxes for simulated galaxies. We find that the simulation results generally match observational measurements, but, perhaps, not in full detail. The differences seem to indica…
We present a novel scenario for the growth of dust grains in galaxies at high-redshift ($z\sim 6$). In our model, the mechanical feedback from massive star clusters evolving within high-density pre-enriched media allows to pile-up a large amount of matter into massive supershells. If the gas metallicity ($\geq$ Z$_{\odot}$), number density ($\geq 10^6$ cm$^{-3}$) and dust-to-gas mass ratio ($\sim 1/150 \times Z$) within the supershell are sufficiently large, such supershells may become optically thick to the starlight emerging from their host star clusters and even to radiation from the Cosmic…
In the last decade, it has become clear that the dust-enshrouded star formation contributes significantly to early galaxy evolution. Detection of dust is therefore essential in determining the properties of galaxies in the high-redshift universe. This requires observations at the (sub-)millimeter wavelengths. Unfortunately, sensitivity and background confusion of single dish observations on the one hand, and mapping efficiency of interferometers on the other hand, pose unique challenges to observers. One promising route to overcome these difficulties is intensity mapping of fluctuations which …
We present a systematic study of the impact of a dust bias on samples of damped Lyman-$α$ absorbers (DLAs). This bias arises as an effect of the magnitude and colour criteria utilized in the Sloan Digital Sky Survey (SDSS) quasar target selection up until data release 7 (DR7). The bias has previously been quantified assuming only a contribution from the dust obscuration. In this work, we apply the full set of magnitude and colour criteria used up until SDSS DR7 in order to quantify the full impact of dust biasing against dusty and metal-rich DLAs. We apply the quasar target selection algorithm…
We consider redshift drift in a general space-time as expressed in terms of physically interpretable multipole series. An important realisation from the derived results is that redshift drift cannot in general be thought of as a direct probe of the average expansion rate of the Universe due to the presence of structure along the light beams from the astrophysical sources to the observer. We also predict the general presence of a dipolar and a quadrupolar offset in the detection of redshift drift for observers placed in locally anisotropic environments.
We investigate the evolution of dust content in galaxies from redshifts z=0 to z=9.5. Using empirically motivated prescriptions, we model galactic-scale properties -- including halo mass, stellar mass, star formation rate, gas mass, and metallicity -- to make predictions for the galactic evolution of dust mass and dust temperature in main sequence galaxies. Our simple analytic model, which predicts that galaxies in the early Universe had greater quantities of dust than their low-redshift counterparts, does a good job at reproducing observed trends between galaxy dust and stellar mass out to z~…
We explore the possibility of detecting the first galaxies with the next generation of space-based far infrared (FIR) telescopes by applying an analytical model of primordial dust emission. Our results indicate that FIR/sub-mm sources at $z \gtrsim 7$ will experience a strong negative K-correction. Systems of a given virial mass would exhibit larger dust luminosities at higher $z$, as a consequence of the increase in dust temperature driven by the higher temperature floor set by the cosmic microwave background. In addition, high-$z$ systems are more concentrated, which enhances the heating eff…
Dust properties within a galaxy are known to change from the diffuse medium to dense clouds due to increased local gas density. However, the question of whether dust properties change with redshift remains elusive. In this paper, using the fact that the mean radiation intensity of the interstellar medium (ISM) of star-forming galaxies increases with redshift, we show that dust properties should change due to increasing efficiency of rotational disruption by radiative torques, an effect named RAdiative Torque Disruption (RATD). We first show that, due to RATD, the size distribution of interstel…
Do low-redshift observations open the doors to an open universe?
Instituto de Física Corpuscular (CSIC-Universitat de València)(粒子物理研究所(西班牙科学理事会-瓦伦西亚大学));Dipartimento di Fisica “E. Pancini”, Università di Napoli “Federico II”(那不勒斯费德里科二世大学E. Pancini物理系);Scuola Superiore Meridionale(南方高等学院);INFN, Sezione di Napoli(意大利国家核物理研究所那不勒斯分部);Institute of Theoretical Astrophysics, University of Oslo(奥斯陆大学理论天体物理研究所)