Search Publications
Solar Modulation of Galactic Cosmic-Ray Protons Based on a Modified Force-field Approach
Qin, Gang; Shen, Zhenning; Yang, Hao +4 more
In this work, a modified force-field approach is established to investigate the long-term solar modulation of galactic cosmic-ray (GCR) protons. In this approach, the solar modulation potential φ is assumed to be energy dependent. As φ also depends on the local interstellar spectrum (LIS), a new proton LIS model is first presented based on data fr…
A LAMOST BHB Catalog and Kinematics Therein. I. Catalog and Halo Properties
Shen, Juntai; Smith, Martin C.; Li, Zhao-Yu +1 more
In this paper, we collect a sample of stars observed both in LAMOST and Gaia, which have colors implying a temperature hotter than 7000 K. We train a machine-learning algorithm on LAMOST spectroscopic data which has been tagged with stellar classifications and metallicities, and use this machine to construct a catalog of blue horizontal branch sta…
The Cepheid Distance to the Narrow-line Seyfert 1 Galaxy NGC 4051
Ferrarese, L.; Vestergaard, M.; Peterson, B. M. +15 more
We derive a distance of D = 16.6 ± 0.3 Mpc (µ = 31.10 ± 0.04 mag) to the archetypal narrow-line Seyfert 1 galaxy NGC 4051 based on Cepheid period-luminosity relations and new Hubble Space Telescope multiband imaging. We identify 419 Cepheid candidates and estimate the distance at both optical and near-infrared wavelengths using subsamples of…
The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. II. The Star-formation History of Andromeda I Derived from Long-period Variables
Javadi, Atefeh; Saremi, Elham; van Loon, Jacco Th. +4 more
An optical monitoring survey in the nearby dwarf galaxies was carried out with the 2.5 m Isaac Newton Telescope. 55 dwarf galaxies and four isolated globular clusters in the Local Group were observed with the Wide Field Camera. The main aims of this survey are to identify the most evolved asymptotic giant branch stars and red supergiants at the en…
Spatially Resolved BPT Mapping of Nearby Seyfert 2 Galaxies
Elvis, Martin; Storchi-Bergmann, Thaisa; Fabbiano, G. +5 more
We present spatially resolved Baldwin-Phillips-Terlevich (BPT) mapping of the extended narrow-line regions (ENLRs) of seven nearby Seyfert 2 galaxies, using Hubble Space Telescope narrowband filter imaging. We construct the BPT diagrams using ≤0"1 resolution emission line images of [O III] λ5007, Hα, [S II] λλ6717, 6731, and Hβ. By mapping these d…
Predicting the Spectrum of UGC 2885, Rubin's Galaxy with Machine Learning
Holwerda, Benne W.; Bailin, Jeremy; Böker, Torsten +10 more
Wu & Peek predict SDSS-quality spectra based on Pan-STARRS broadband grizy images using machine learning (ML). In this article, we test their prediction for a unique object, UGC 2885 ("Rubin's galaxy"), the largest and most massive, isolated disk galaxy in the local universe (D < 100 Mpc). After obtaining the ML predicted spectrum, we compa…
Mixed Modes and Asteroseismic Surface Effects. II. Subgiant Systematics
Bieryla, Allyson; Latham, David W.; Basu, Sarbani +3 more
Models of solar-like oscillators yield acoustic modes at different frequencies than would be seen in actual stars possessing identical interior structure, due to modeling error near the surface. This asteroseismic "surface term" must be corrected when mode frequencies are used to infer stellar structure. Subgiants exhibit oscillations of mixed aco…
A Distance-deviation Consistency and Model-independent Method to Test the Cosmic Distance-Duality Relation
Fang, Guanwen; Zhou, Chichun; Hu, Jian +2 more
A distance-deviation consistency and model-independent method to test the cosmic distance-duality relation (CDDR) is provided. This method is worthy of attention for two reasons. First, a distance-deviation consistency method is used to pair subsamples: instead of pairing subsamples with redshift deviations smaller than a value of, say, $\left|{\r…
Kinetic Alfvén Waves in Space Plasma Environment with κ-electrons
Lakhina, G. S.; Singh, S. V.; Barik, K. C.
A resonant instability of kinetic Alfvén waves (KAWs) driven by ion beam is discussed through a theoretical model encompassing Maxwellian background ions and beam ions and non-Maxwellian κ-electrons. The ion beam velocity alone as a source is able to excite the KAWs up to a significant growth. The non-Maxwellian parameter κ impedes the growth of K…
Resolved Nuclear Kinematics Link the Formation and Growth of Nuclear Star Clusters with the Evolution of Their Early- and Late-type Hosts
Böker, Torsten; Neumayer, Nadine; Emsellem, Eric +7 more
We present parsec-scale kinematics of 11 nearby galactic nuclei, derived from adaptive-optics assisted integral-field spectroscopy at (near-infrared) CO band-head wavelengths. We focus our analysis on the balance between ordered rotation and random motions, which can provide insights into the dominant formation mechanism of nuclear star clusters (…