分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We present measurements of [NeIII]{\lambda}3869 emission in z~1 low-mass galaxies taken from the Keck/DEIMOS spectroscopic surveys HALO7D and DEEPWinds. We identify 167 individual galaxies with significant [NeIII] emission lines, including 112 "dwarf" galaxies with log(M_{\star}/M_{\odot}) 7 galaxies identified in JWST Early Release Observations, finding four HALO7D dwarfs with similar size, metallicity, and star formation properties.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Sukanya Chakrabarti
Joshua D. Simon
Peter A. Craig
Henrique Reggiani
Puragra Guhathakurta
Paul A. Dalba
Evan N. Kirby
Philip Chang
Daniel R. Hey
Alessandro Savino
Marla Geha
摘要： We describe the discovery of a solar neighborhood ($d=474$~pc) binary system consisting of a main-sequence sunlike star and a massive non-interacting black hole candidate. We selected this system from the \textit{Gaia} DR3 binary catalog based on its high mass ratio and location close to the main sequence. The spectral energy distribution (SED) of the visible star is well described by a single stellar model, indicating that no contribution from another luminous source is needed to fit the observed photometry. We derive stellar parameters from a high S/N Magellan/MIKE spectrum, classifying the star as a main-sequence star with $T_{\rm eff} = 5972~\rm K$, $\log{g} = 4.54$, and $M = 0.91$~\msun. The spectrum also shows no indication of a second luminous component. We have measured radial velocities of this system with the Automated Planet Finder, Magellan, and Keck over the past three months, which we use to determine the spectroscopic orbit of the binary. We show that the velocity data are consistent with the \textit{Gaia} astrometric orbit and provide independent evidence for a massive dark companion. From a combined fit of the astrometric and spectroscopic data, we derive a companion mass of $11.9^{+2.0}_{-1.6}$\msun. We conclude that this binary system harbors a massive black hole on an eccentric $(e =0.45 \pm 0.02)$, long-period ($185.4 \pm 0.1$ d) orbit. The main-sequence star that orbits this black hole is moderately metal-poor ($\mbox{[Fe/H]} = -0.30$), on a Galactic orbit similar to thin disk stars. Our conclusions are independent of \cite{ElBadry2022Disc}, who recently reported the discovery of the same system, and find a marginally lower companion mass than we do here.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Weichen Wang
Susan A. Kassin
S. M. Faber
David C. Koo
Emily C. Cunningham
Hassen M. Yesuf
Guillermo Barro
Puragra Guhathakurta
Benjamin Weiner
Alexander de la Vega
Yicheng Guo
Timothy M Heckman
Camilla Pacifici
Bingjie Wang
Charlotte Welker
摘要： Strong galactic winds are ubiquitous at $z\gtrsim 1$. However, it is not well known where inside galaxies these winds are launched from. We study the cool winds ($\sim 10^4$\,K) in two spatial regions of a massive galaxy at $z=1.3$, which we nickname the "Baltimore Oriole's Nest." The galaxy has a stellar mass of $10^{10.3\pm 0.3} M_\odot$, is located on the star-forming main sequence, and has a morphology indicative of a recent merger. Gas kinematics indicate a dynamically complex system with velocity gradients ranging from 0 to 60 $\mathrm{km}\cdot\mathrm{s}^{-1}$. The two regions studied are: a dust-reddened center (Central region), and a blue arc at 7 kpc from the center (Arc region). We measure the \ion{Fe}{2} and \ion{Mg}{2} absorption line profiles from deep Keck/DEIMOS spectra. Blueshifted wings up to 450 km$\cdot$s$^{-1}$ are found for both regions. The \ion{Fe}{2} column densities of winds are $10^{14.7\pm 0.2}\,\mathrm{cm}^{-2}$ and $10^{14.6\pm 0.2}\,\mathrm{cm}^{-2}$ toward the Central and Arc regions, respectively. Our measurements suggest that the winds are most likely launched from both regions. The winds may be driven by the spatially extended star formation, the surface density of which is around 0.2 $M_\odot\,\mathrm{yr}^{-1}\cdot \mathrm{kpc}^{-2}$ in both regions. The mass outflow rates are estimated to be $4\,M_\odot\,\mathrm{yr}^{-1}$ and $3\,M_\odot\,\mathrm{yr}^{-1}$ for the Central and Arc regions, with uncertainties of one order-of-magnitude or more. Findings of this work and a few previous studies suggest that the cool galactic winds at $z\gtrsim 1$ might be commonly launched from the entire spatial extents of their host galaxies due to extended galaxy star formation.
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