We investigate the stellar mass–black hole mass (
Experiments have been conducted in the DIII-D tokamak to explore the
- NSF-PAR ID:
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Nuclear Fusion
- Page Range / eLocation ID:
- Article No. 106004
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
We investigate the stellar mass–black hole mass (
) relation with type 1 active galactic nuclei (AGNs) down to , corresponding to a ≃ −21 absolute magnitude in rest-frame ultraviolet, at z= 2–2.5. Exploiting the deep and large-area spectroscopic survey of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX), we identify 66 type 1 AGNs with ranging from 107–1010 M⊙that are measured with single-epoch virial method using C ivemission lines detected in the HETDEX spectra. of the host galaxies are estimated from optical to near-infrared photometric data taken with Spitzer, the Wide-field Infrared Survey Explorer, and ground-based 4–8 m class telescopes by CIGALEspectral energy distribution (SED) fitting. We further assess the validity of SED fitting in two cases by host-nuclear decomposition performed through surface brightness profile fitting on spatially resolved host galaxies with the James Webb Space Telescope/NIRCam CEERS data. We obtain the relation covering the unexplored low-mass ranges of , and conduct forward modeling to fully account for the selection biases and observational uncertainties. The intrinsic relation at z∼ 2 has a moderate positive offset of 0.52 ± 0.14 dex from the local relation, suggestive of more efficient black hole growth at higher redshift even in the low-mass regime of . Our relation is inconsistent with the suppression at the low- regime predicted by recent hydrodynamic simulations at a 98% confidence level, suggesting that feedback in the low-mass systems may be weaker than those produced in hydrodynamic simulations.
J= 1 → 0) observations for the EDGE-CALIFA survey, which is a mapping survey of 126 nearby galaxies at a typical spatial resolution of 1.5 kpc. Using detected12CO emission as a prior, we detect13CO in 41 galaxies via integrated line flux over the entire galaxy and in 30 galaxies via integrated line intensity in resolved synthesized beams. Incorporating our CO observations and optical IFU spectroscopy, we perform a systematic comparison between the line ratio and the properties of the stars and ionized gas. Higher values are found in interacting galaxies compared to those in noninteracting galaxies. The global slightly increases with infrared color F60/ F100but appears insensitive to other host-galaxy properties such as morphology, stellar mass, or galaxy size. We also present azimuthally averaged profiles for our sample up to a galactocentric radius of 0.4 r25(∼6 kpc), taking into account the13CO nondetections by spectral stacking. The radial profiles of are quite flat across our sample. Within galactocentric distances of 0.2 r25, the azimuthally averaged increases with the star formation rate. However, Spearman rank correlation tests show the azimuthally averaged does not strongly correlate with any other gas or stellar properties in general, especially beyond 0.2 r25from the galaxy centers. Our findings suggest that in the complex environments in galaxy disks, is not a sensitive tracer for ISM properties. Dynamical disturbances, like galaxy interactions or the presence of a bar, also have an overall impact on , which further complicates the interpretations of variations.
Fast radio bursts (FRBs) are brief, energetic, typically extragalactic flashes of radio emission whose progenitors are largely unknown. Although studying the FRB population is essential for understanding how these astrophysical phenomena occur, such studies have been difficult to conduct without large numbers of FRBs and characterizable observational biases. Using the recently released catalog of 536 FRBs published by the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) collaboration, we present a study of the FRB population that also calibrates for selection effects. Assuming a Schechter function, we infer a characteristic energy cut-off of
erg and a differential power-law index of γ= . Simultaneously, we infer a volumetric rate of [ (stat.) Gpc−3yr−1above a pivot energy of 1039erg and below a scattering timescale of 10 ms at 600 MHz, and find we cannot significantly constrain the cosmic evolution of the FRB population with star-formation rate. Modeling the host’s dispersion measure (DM) contribution as a log-normal distribution and assuming a total Galactic contribution of 80 pc cm−3, we find a median value of pc cm−3, comparable with values typically used in the literature. Proposed models for FRB progenitors should be consistent with the energetics and abundances of the full FRB population predicted by our results. Finally, we infer the redshift distribution of FRBs detected with CHIME, which will be tested with the localizations and redshifts enabled by the upcoming CHIME/FRB Outriggers project.
While radiation is known to degrade AlGaN/GaN high-electron-mobility transistors (HEMTs), the question remains on the extent of damage governed by the presence of an electrical field in the device. In this study, we induced displacement damage in HEMTs in both ON and OFF states by irradiating with 2.8 MeV Au4+ion to fluence levels ranging from
to ions cm−2, or 0.001–2 displacement per atom (dpa). Electrical measurement is done in situ, and high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray (EDX), geometrical phase analysis (GPA), and micro-Raman are performed on the highest fluence of Au4+irradiated devices. The selected heavy ion irradiation causes cascade damage in the passivation, AlGaN, and GaN layers and at all associated interfaces. After just 0.1 dpa, the current density in the ON-mode device deteriorates by two orders of magnitude, whereas the OFF-mode device totally ceases to operate. Moreover, six orders of magnitude increase in leakage current and loss of gate control over the 2-dimensional electron gas channel are observed. GPA and Raman analysis reveal strain relaxation after a 2 dpa damage level in devices. Significant defects and intermixing of atoms near AlGaN/GaN interfaces and GaN layer are found from HRTEM and EDX analyses, which can substantially alter device characteristics and result in complete failure.
We present a multiwavelength analysis of the galaxy cluster SPT-CL J0607-4448 (SPT0607), which is one of the most distant clusters discovered by the South Pole Telescope at
z= 1.4010 ± 0.0028. The high-redshift cluster shows clear signs of being relaxed with well-regulated feedback from the active galactic nucleus (AGN) in the brightest cluster galaxy (BCG). Using Chandra X-ray data, we construct thermodynamic profiles and determine the properties of the intracluster medium. The cool-core nature of the cluster is supported by a centrally peaked density profile and low central entropy ( keV cm2), which we estimate assuming an isothermal temperature profile due to the limited spectral information given the distance to the cluster. Using the density profile and gas cooling time inferred from the X-ray data, we find a mass-cooling rate yr−1. From optical spectroscopy and photometry around the [O ii] emission line, we estimate that the BCG star formation rate is yr−1, roughly two orders of magnitude lower than the predicted mass-cooling rate. In addition, using ATCA radio data at 2.1 GHz, we measure a radio jet power erg s−1, which is consistent with the X-ray cooling luminosity ( erg s−1within rcool= 43 kpc). These findings suggest that SPT0607 is a relaxed, cool-core cluster with AGN-regulated cooling at an epoch shortly after cluster formation, implying that the balance between cooling and feedback can be reached quickly. We discuss the implications for these findings on the evolution of AGN feedback in galaxy clusters.