分类： 天文学 >> 天文学 提交时间： 2023-02-19
J. D. R. Pierel
D. O. Jones
W. D. Kenworthy
M. Dai
R. Kessler
C. Ashall
A. Do
E. R. Peterson
B. J. Shappee
M. R. Siebert
T. Barna
T. G. Brink
J. Burke
A. Calamida
Y. Camacho-Neves
T. de Jaeger
A. V. Filippenko
R. J. Foley
L. Galbany
O. D. Fox
摘要： A large fraction of Type Ia supernova (SN Ia) observations over the next decade will be in the near-infrared (NIR), at wavelengths beyond the reach of the current standard light-curve model for SN Ia cosmology, SALT3 ($\sim 2800$--8700$A$ central filter wavelength). To harness this new SN Ia sample and reduce future light-curve standardization systematic uncertainties, we train SALT3 at NIR wavelengths (SALT3-NIR) up to 2 $\mu$m with the open-source model-training software SALTShaker, which can easily accommodate future observations. Using simulated data we show that the training process constrains the NIR model to $\sim 2$--3% across the phase range ($-20$ to $50$ days). We find that Hubble residual (HR) scatter is smaller using the NIR alone or optical+NIR compared to optical alone, by up to $\sim 30$% depending on filter choice (95% confidence). There is significant correlation between NIR light-curve stretch measurements and luminosity, with stretch and color corrections often improving HR scatter by up to $\sim20%$. For SN Ia observations expected from the \textit{Roman Space Telescope}, SALT3-NIR increases the amount of usable data in the SALT framework by $\sim 20$% at redshift $z\lesssim0.4$ and by $\sim 50$% at $z\lesssim0.15$. The SALT3-NIR model is part of the open-source {\tt SNCosmo} and {\tt SNANA} SN Ia cosmology packages.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
G. J. Bendo
S. A. Urquhart
S. Serjeant
T. Bakx
M. Hagimoto
P. Cox
R. Neri
M. D. Lehnert
H. Dannerbauer
A. Amvrosiadis
P. Andreani
A. J. Baker
A. Beelen
S. Berta
E. Borsato
V. Buat
K. M. Butler
A. Cooray
G. De Zotti
L. Dunne
摘要： We present 101 and 151 GHz ALMA continuum images for 85 fields selected from Herschel observations that have 500 micron flux densities >80 mJy and 250-500 micron colours consistent with z > 2, most of which are expected to be gravitationally lensed or hyperluminous infrared galaxies. Approximately half of the Herschel 500 micron sources were resolved into multiple ALMA sources, but 11 of the 15 brightest 500 micron Herschel sources correspond to individual ALMA sources. For the 37 fields containing either a single source with a spectroscopic redshift or two sources with the same spectroscopic redshift, we examined the colour temperatures and dust emissivity indices. The colour temperatures only vary weakly with redshift and are statistically consistent with no redshift-dependent temperature variations, which generally corresponds to results from other samples selected in far-infrared, submillimetre, or millimetre bands but not to results from samples selected in optical or near-infrared bands. The dust emissivity indices, with very few exceptions, are largely consistent with a value of 2. We also compared spectroscopic redshifts to photometric redshifts based on spectral energy distribution templates designed for infrared-bright high-redshift galaxies. While the templates systematically underestimate the redshifts by ~15%, the inclusion of ALMA data decreases the scatter in the predicted redshifts by a factor of ~2, illustrating the potential usefulness of these millimetre data for estimating photometric redshifts.
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