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Creators/Authors contains: "Chen, C -C"

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  1. ABSTRACT We present a new method for modelling the kinematics of galaxies from interferometric observations by performing the optimization of the kinematic model parameters directly in visibility space instead of the conventional approach of fitting velocity fields produced with the clean algorithm in real-space. We demonstrate our method on Atacama Large Millimeter/submillimeter Array (ALMA) observations of $$^{12}$$CO (2–1), (3–2), or (4–3) emission lines from an initial sample of 30 massive 850 $$\mu$$m-selected dusty star-forming galaxies with far-infrared luminosities $$\gtrsim$$\, 10^{12}$$ L$$_{\odot }$$ in the redshift range $$z \sim$$ 1.2–4.7. Using the results from our modelling analysis for the 12 of the 20 sources with the highest signal-to-noise emission lines that show disc-like kinematics, we conclude the following: (i) our sample prefers a CO-to-$$H_2$$ conversion factor, of $$\alpha _{\rm CO} = 0.74 \pm 0.37$$; (ii) these far-infrared luminous galaxies follow a similar Tully–Fisher relation between the circular velocity, $$V_{\rm circ}$$, and baryonic mass, $$M_{\rm b}$$, as less strongly star-forming samples at high redshift, but extend this relation to much higher masses – showing that these are some of the most massive disc-like galaxies in the Universe; (iii) finally, we demonstrate support for an evolutionary link between massive high-redshift dusty star-forming galaxies and the formation of local early-type galaxies using the both the distributions of the baryonic and kinematic masses of these two populations on the $$M_{\rm b}$$ – $$\sigma$$ plane and their relative space densities. 
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  2. Abstract We present JWST NIRCam imaging targeting 13z ~ 3 infrared-luminous (LIR ∼ 5 × 1012L) galaxies from the ALESS survey with uniquely deep, high-resolution (0 . 08–0 . 16) Atacama Large Millimeter/submillimeter Array 870μm imaging. The 2.0–4.4μm (observed frame) NIRCam imaging reveals the rest-frame near-infrared stellar emission in these submillimeter-selected galaxies at the same (sub)kiloparsec resolution as the 870μm dust continuum. The newly revealed stellar morphologies show striking similarities with the dust continuum morphologies at 870μm, with the centers and position angles agreeing for most sources, clearly illustrating that the spatial offsets reported previously between the 870μm and Hubble Space Telescope morphologies were due to strong differential dust obscuration. The F444W sizes are 78% ± 21% larger than those measured at 870μm, in contrast to recent results from hydrodynamical simulations that predict larger 870μm sizes. We report evidence for significant dust obscuration in F444W for the highest-redshift sources, emphasizing the importance of longer-wavelength MIRI imaging. The majority of the sources show evidence that they are undergoing mergers/interactions, including tidal tails/plumes—some of which are also detected at 870μm. We find a clear correlation between NIRCam colors and 870μm surface brightness on  ∼1 kpc scales, indicating that the galaxies are primarily red due to dust—not stellar age—and we show that the dust structure on  ∼kpc scales is broadly similar to that in nearby galaxies. Finally, we find no strong stellar bars in the rest-frame near-infrared, suggesting the extended bar-like features seen at 870μm are highly obscured and/or gas-dominated structures that are likely early precursors to significant bulge growth. 
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  3. Laser cooling is a key ingredient for quantum control of atomic systems in a variety of settings. In divalent atoms, two-stage Doppler cooling is typically used to bring atoms to the uK regime. Here, we implement a pulsed radial cooling scheme using the ultranarrow 1S0-3P0 clock transition in ytterbium to realize sub-recoil temperatures, down to tens of nK. Together with sideband cooling along the one-dimensional lattice axis, we efficiently prepare atoms in shallow lattices at an energy of 6 lattice recoils. Under these conditions key limits on lattice clock accuracy and instability are reduced, opening the door to dramatic improvements. Furthermore, tunneling shifts in the shallow lattice do not compromise clock accuracy at the 10-19 level. 
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  4. Galaxies grow inefficiently, with only a small percentage of the available gas converted into stars each free-fall time. Feedback processes, such as outflowing winds driven by radiation pressure, supernovae, or supermassive black hole accretion, can act to halt star formation if they heat or expel the gas supply. We report a molecular outflow launched from a dust-rich star-forming galaxy at redshift 5.3, 1 billion years after the Big Bang. The outflow reaches velocities up to 800 kilometers per second relative to the galaxy, is resolved into multiple clumps, and carries mass at a rate within a factor of 2 of the star formation rate. Our results show that molecular outflows can remove a large fraction of the gas available for star formation from galaxies at high redshift. 
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  5. The Askaryan Radio Array (ARA) is an ultrahigh energy (UHE, >10^17  eV) neutrino detector designed to observe neutrinos by searching for the radio waves emitted by the relativistic products of neutrino-nucleon interactions in Antarctic ice. In this paper, we present constraints on the diffuse flux of ultrahigh energy neutrinos between 1016 and 1021  eV resulting from a search for neutrinos in two complementary analyses, both analyzing four years of data (2013–2016) from the two deep stations (A2, A3) operating at that time. We place a 90% CL upper limit on the diffuse all flavor neutrino flux at 1018  eV of EF(E)=5.6×10^−16  cm^−2 s^−1 sr^−1. This analysis includes four times the exposure of the previous ARA result and represents approximately 1/5^th the exposure expected from operating ARA until the end of 2022. 
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  6. null (Ed.)