Submitted to the AAS corridor (ApJ Letters or ApJ). It is difficult to visualize the uniformity of these strange clusters. Our best attempt is Fig. 2, where we compare them to globular clusters in Virgo galaxies
It was recently proposed that the dark matter-deficient ultra-diffuse galaxies DF2 and DF4 in the NGC1052 group could be the products of a "bullet dwarf" collision between two gas-rich progenitor galaxies. In this model DF2 and DF4 formed at the same time in the immediate aftermath of the collision, and a strong prediction is that their globular clusters should have nearly identical stellar populations. Here we test this prediction by measuring accurate F606W-F814W colors from deep HST/ACS imaging. We find that the clusters are extremely homogeneous. The mean color difference between the globular clusters in DF2 and DF4 is $-0.003\pm 0.005$ mag and the observed scatter for the combined sample of 18 clusters with $M_V<-8.6$ in both galaxies is $0.015 \pm 0.002$ mag. After accounting for observational uncertainties and stochastic cluster-to-cluster variation in the number of red giants, the remaining scatter is $0.008^{+0.005}_{-0.006}$ mag. Both the color difference and the scatter are an order of magnitude smaller than in other dwarf galaxies, and we infer that the bullet scenario passes an important test that could have falsified it. No other formation models have predicted this extreme uniformity of the globular clusters in the two galaxies. We find that the galaxies themselves are slightly redder than the clusters, consistent with a previously-measured metallicity difference. Numerical simulations have shown that such differences are expected in the bullet scenario, as the galaxies continued to self-enrich after the formation of the globular clusters.
10 pages, 8 figures, accepted for publication in MNRAS
We numerically follow the response of density-enhanced slabs to impulsive, localized, transverse velocity perturbations by working in the framework of ideal magnetohydrodynamics (MHD). Both linear and nonlinear regimes are addressed. Kink wave trains are seen to develop along the examined slabs, sharing the characteristics that more oscillatory patterns emerge with time and that the apparent wavelength increases with distance at a given instant. Two features nonetheless arise due to nonlinearity, one being a density cavity close to the exciter and the other being the appearance of shocks both outside and inside the nominal slab. These features may be relevant for understanding the interaction between magnetic structures and such explosive events as coronal mass ejections. Our numerical findings on kink wave trains in solar coronal slabs are discussed in connection with typical measurements of streamer waves.
23 pages, 8 Figures, 1 Table. Accepted to ApJ
We construct a physically-parameterized probabilistic autoencoder (PAE) to learn the intrinsic diversity of type Ia supernovae (SNe Ia) from a sparse set of spectral time series. The PAE is a two-stage generative model, composed of an Auto-Encoder (AE) which is interpreted probabilistically after training using a Normalizing Flow (NF). We demonstrate that the PAE learns a low-dimensional latent space that captures the nonlinear range of features that exists within the population, and can accurately model the spectral evolution of SNe Ia across the full range of wavelength and observation times directly from the data. By introducing a correlation penalty term and multi-stage training setup alongside our physically-parameterized network we show that intrinsic and extrinsic modes of variability can be separated during training, removing the need for the additional models to perform magnitude standardization. We then use our PAE in a number of downstream tasks on SNe Ia for increasingly precise cosmological analyses, including automatic detection of SN outliers, the generation of samples consistent with the data distribution, and solving the inverse problem in the presence of noisy and incomplete data to constrain cosmological distance measurements. We find that the optimal number of intrinsic model parameters appears to be three, in line with previous studies, and show that we can standardize our test sample of SNe Ia with an RMS of $0.091 \pm 0.010$ mag, which corresponds to $0.074 \pm 0.010$ mag if peculiar velocity contributions are removed. Trained models and codes are released at \href{https://github.com/georgestein/suPAErnova}{github.com/georgestein/suPAErnova}
Submitted to A&A Letters, lens model and redshift catalogue available at: this https URL
We present our lens mass model of SMACS J0723, the first strong gravitational lens observed by the James Webb Space Telescope (JWST). We use data from the Hubble Space Telescope and Multi Unit Spectroscopic Explorer (MUSE) to build our 'pre-JWST' lens model, and refine it with newly available JWST near-infrared imaging in our JWST model. To reproduce the positions of all multiple lensed images with good accuracy, the adopted mass parameterization consists of one cluster-scale component, accounting mainly for the dark matter distribution, the galaxy cluster members and an external shear component. The pre-JWST model has, as constraints, 19 multiple images from six background sources, of which four have secure spectroscopic redshift measurements from this work. The JWST model has more than twice the number of constraints, 27 additional multiple images from another ten lensed sources. Both models can reproduce very well the multiple image positions with a $\delta_{rms}$ of $0.39''$ and $0.51''$, for the pre-JWST and JWST models, respectively. The total mass estimates within a radius of 128~kpc (~ the Einstein radius) are $7.9_{-0.2}^{+0.3}\times 10^{13}\rm M_{\odot}$ and $8.6_{-0.2}^{+0.2}\times 10^{13}\rm M_{\odot}$, for the pre-JWST and JWST models, respectively. We predict with our mass models the redshifts of the newly detected JWST sources, which are crucial information for systems without spectroscopic measurements for further studies and follow-up observations. Interestingly, one family detected with JWST is found to be at a very high redshift, $z>7.5$ (68% confidence level) and with one image having lensing magnification of $|\mu|=9.8_{-1.1}^{+0.9}$, making it an interesting case for future studies. The lens models, including magnification maps and redshifts estimated from the model are made publicly available, along with the full spectroscopic redshift catalogue from MUSE.
35 pages, 19 figures, 4 tables. Submitted to ApJS. Mosaics and photometric catalogs can be accessed online this https URL
16 pages, 7 figures, submitted to ApJ
Accepted for publication in Astrophysical Journal, 22 pages, 5 figure
Submitted to MNRAS
15 pages, 8 figures, accepted for publication in the Astrophysical Journal
19 pages, 6 figures
Submitted to MNRAS. 18 pages, 11 figures
23 pages, Comments are welcome
20 pages, 17 figures, accepted for publication in MNRAS
10 pages, 8 figures, accepted to the ICML 2022 Machine Learning for Astrophysics workshop
Accepted by ApJ, Jul 2022, Comments welcome
26 pages, 12 figures, Review in a topical collection series of Astrophysics and Space Sciences on the proposed Polstar satellite. arXiv admin note: substantial text overlap with arXiv:2111.11552
8.5 pages, 4 figs. The first constraints on alternative dark energy and modified gravity using Pantheon+ sample
Submitted to ApJ
17 pages, 6 figures, accepted for publication in AJ
10 pages, 9 figures. Published in SPIE Proc
18 pages, 9 figures
Accepted for publication in MNRAS Letters
11 pages, 6 figures, submitted to MNRAS
30 pages, 11 figures, accepted for publication in PASJ
Submitted to Monthly Notices of the Royal Astronomical Society
11 pages, 4 figures, accepted for publication on MNRAS
5 pages, 2 figures
12 pages; to be submitted to ApJ
26 pages, 22 figures, submitted to MNRAS
published in Astronomy Report, translated by Yandex translator with correction of scientific lexis, 16 pages, 6 figures, 3 table, appendix
13 pages, 12 figures, accepted for publication in MNRAS
Submitted to A&A. Comments welcome
Accepted for publication by Monthly Notices of the Royal Astronomical Society
39 pages, 10 Figures and 7 Tables. INAF Technical Report n. 149 (2022). this http URL
14 pages plus appendices, 15 figures
Presented at SPIE Astronomical Telescopes + Instrumentation 2022
14 pages, 11 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society
9 pages, 8 figures
Accepted to AJ. 19 pages, 15 figures
22 pages, 27 figures, 4 tables. Submitted to MNRAS. Comments welcome
26 pages, 5 figures
18 pages, 14 figures
8 pages + appendices and references; 2 tables and 1 figure
28 pages, 9 figures