Search Publications
Do Current X-Ray Observations Capture Most of the Black-hole Accretion at High Redshifts?
Papovich, Casey; Yang, Guang; Estrada-Carpenter, Vicente +4 more
The cosmic black hole accretion density (BHAD) is critical for our understanding of the formation and evolution of supermassive black holes (BHs). However, at high redshifts (z > 3), X-ray observations report BHADs significantly (~10 times) lower than those predicted by cosmological simulations. It is therefore paramount to constrain the high-z…
The 3.3 µm Infrared Emission Feature: Observational and Laboratory Constraints on Its Carrier
Tokunaga, Alan T.; Bernstein, Lawrence S.
We examine the self-consistency of laboratory and observational data for potential carriers of the 3.3 µm infrared emission feature (IEF), a member of the ubiquitous family of strong interstellar IEFs at 3.3, 3.4, 6.2, 7.7, 8.6, 11.2, and 12.7 µm. Previous studies have shown that most Galactic sources (reflection nebulae, H II regions,…
Modification of icy planetesimals by early thermal evolution and collisions: Constraints for formation time and initial size of comets and small KBOs
Jutzi, Martin; Golabek, Gregor J.
Comets and small Kuiper belt objects are considered to be among the most primitive objects in the solar system as comets like C/1995 O1 Hale-Bopp are rich in highly volatile ices like CO. It has been suggested that early in the solar system evolution the precursors of both groups, the so-called icy planetesimals, were modified by both short-lived …
Astrophysical properties of newly discovered Magellanic Cloud star clusters
Piatti, Andrés E.
New star cluster candidates projected toward the Large and Small Magellanic Clouds (LMC, SMC) have been recently discovered from relatively deep imaging surveys. Here, we conduct a sound analysis of 24 star cluster candidates located in the outer regions of the LMC and SMC using point spread function photometry produced by the Survey of the Magell…
Effects of solar flares and coronal mass ejections on Earth's horizontal magnetic field and solar wind parameters during the minimum solar cycle 24
Yoshikawa, A.; Syed Zafar, S. N. A.; Umar, R. +3 more
Previous studies have reported that coronal mass ejections (CMEs) and solar flares lead to the development of huge storms and high-speed streams. Our aim in this paper is to investigate the response of the geomagnetic index SYM/H to the solar wind parameters, such as solar wind speed V, dynamic pressure P, input energy IE and the interplanetary ma…
NGC 147 Corroborates the Break in the Stellar Mass-Stellar Metallicity Relation for Galaxies
Leethochawalit, Nicha; Kirby, Evan N.; Zhuang, Zhuyun +1 more
The stellar mass-stellar metallicity relation (MZR) is an essential approach to probing the chemical evolution of galaxies. It reflects the balance between galactic feedback and gravitational potential as a function of stellar mass. However, the current MZR of local dwarf satellite galaxies (M* ≲ 108 M⊙; measured f…
Observations of whistler mode waves by Solar Orbiter's RPW Low Frequency Receiver (LFR): In-flight performance and first results
Maksimovic, M.; Bale, S. D.; Chust, T. +29 more
Context. The Radio and Plasma Waves (RPW) instrument is one of the four in situ instruments of the ESA/NASA Solar Orbiter mission, which was successfully launched on February 10, 2020. The Low Frequency Receiver (LFR) is one of its subsystems, designed to characterize the low frequency electric (quasi-DC - 10 kHz) and magnetic (∼1 Hz-10 kHz) field…
Characteristics of source locations and solar cycle distribution of the strong solar proton events (≥1000 pfu) from 1976 to 2018
Le, Gui-Ming; Zhao, Ming-Xian; Qi-Li +3 more
We studied the source locations and solar cycle distribution of strong solar proton events (SPEs, ≥1000 pfu) measured at the Earth from 1976 to 2018. There were 43 strong SPEs during this period. 27.9 per cent of the strong SPEs were ground level enhancement (GLE) events. We detect more strong SPEs coming from the Western hemisphere. The strong SP…
Kelvin-Helmholtz Instability Associated with Reconnection and Ultra Low Frequency Waves at the Ground: A Case Study
Grigorenko, E. E.; Kronberg, E. A.; Nykyri, K. +7 more
The Kelvin-Helmholtz instability (KHI) and its effects relating to the transfer of energy and mass from the solar wind into the magnetosphere remain an important focus of magnetospheric physics. One such effect is the generation of Pc4-Pc5 ultra low frequency (ULF) waves (periods of 45-600 s). On 3 July 2007 at ~0500 magnetic local time the Cluste…
Prediction of Soft Proton Intensities in the Near-Earth Space Using Machine Learning
Tiengo, Andrea; Allen, Robert C.; Gastaldello, Fabio +14 more
The spatial distribution of energetic protons contributes to the understanding of magnetospheric dynamics. Based upon 17 yr of the Cluster/RAPID observations, we have derived machine-learning-based models to predict the proton intensities at energies from 28 to 962 keV in the 3D terrestrial magnetosphere at radial distances between 6 and 22 R…