Recent experiments aiming to measure phenomena predicted by strong field quantum electrodynamics have done so by colliding relativistic electron beams and high-power lasers. In such experiments, ...measurements of the collision parameters are not always feasible, however, precise knowledge of these parameters is required for accurate tests of strong-field quantum electrodynamics. Here, we present a novel Bayesian inference procedure which infers collision parameters that could not be measured on-shot. This procedure is applicable to all-optical non-linear Compton scattering experiments investigating radiation reaction. The framework allows multiple diagnostics to be combined self-consistently and facilitates the inclusion of prior or known information pertaining to the collision parameters. Using this Bayesian analysis, the relative validity of the classical, quantum-continuous and quantum-stochastic models of radiation reaction were compared for a series of test cases, which demonstrate the accuracy and model selection capability of the framework and and highlight its robustness in the event that the experimental values of fixed parameters differ from their values in the models.
We test the merger-induced dual active galactic nuclei (dAGN) paradigm using a sample of 35 radio galaxy pairs from the SDSS Stripe 82 field. Using Keck optical spectroscopy, we confirm 21 pairs have ...consistent redshifts, constituting kinematic pairs; the remaining 14 pairs are line-of-sight projections. We classify the optical spectral signatures via emission line ratios, equivalent widths, and excess of radio power above star-formation predicted outputs. We find 6 galaxies are classified as LINERs and 7 are AGN/starburst composites. Most of the LINERs are retired galaxies, while the composites likely have AGN contribution. All of the kinematic pairs exhibit radio power more than 10\(\times\) above the level expected from just star-formation, suggestive of a radio AGN contribution. We also analyze high-resolution (0.3") imaging at 6 GHz from the NSF's Karl G. Jansky Very Large Array for 17 of the kinematic pairs. We find 6 pairs (2 new, 4 previously known) host two separate radio cores, confirming their status as dAGNs. The remaining 11 pairs contain single AGNs, with most exhibiting prominent jets/lobes overlapping their companion. Our final census indicates a dAGN duty cycle slightly higher than predictions of purely stochastic fueling, although a larger sample (potentially culled from VLASS) is needed to fully address the dAGN fraction. We conclude that while dAGNs in the Stripe 82 field are rare, the merger process plays some role in their triggering and it facilitates low to moderate levels of accretion.
We report Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) deep IR (F160W) imaging of SDSS J1608+2716. This system, located at a redshift of z=2.575, was recently reported as a triple quasar ...candidate with subarcsecond separations (\(\sim0.25''\)) based on selection from Gaia astrometry and follow-up Keck adaptive optics-assisted integral field unit spectroscopy. Our new HST deep IR imaging reveals the presence of a fourth point-like component located \(\sim0.9''\) away from the triple system. Additionally, we detect an edge-on disk galaxy located in between the four point sources. The entire system exhibits a characteristic cusp structure in the context of strong gravitational lensing, and the observed image configuration can be successfully reproduced using a lens model based on a singular isothermal ellipsoid mass profile. These findings indicate that this system is a quadruply lensed quasar. Our results highlight the challenges associated with identifying dual/multiple quasars on \(\sim\)kpc scales at high redshifts, and emphasize the crucial role of deep, high-resolution IR imaging in robustly confirming such systems.
Dual quasars at small physical separations are an important precursor phase
of galaxy mergers, ultimately leading to the coalescence of the two
supermassive black holes. Starting from a sample of ...dual/lensed quasar
candidates discovered using astrometric jitter in Gaia data, we present a pilot
case study of one of the most promising yet puzzling candidate dual quasars at
cosmic noon (z$\sim$1.8). Using multi-wavelength imaging and spectroscopy from
X-ray to radio, we test whether the J0823+2418 system is two individual quasars
in a bound pair at separation$\sim$0.64'', or instead a single quasar being
gravitationally lensed by a foreground galaxy. We find consistent flux ratios
($\sim$1.25-1.45) between the two sources in optical, NIR, UV, and radio, and
thus similar spectral energy distributions, suggesting a strong lensing
scenario. However, differences in the radio spectral index, as well as changing
X-ray fluxes, hint at either a dual quasar with otherwise nearly identical
properties, or perhaps lensing-based time lag of $\sim$3 days paired with
intrinsic variability. We find with lens mass modeling that the relative NIR
positions and magnitudes of the two quasars and a marginally detected central
galaxy are consistent with strong lensing. Archival SDSS spectra likewise
suggest a foreground absorber via Mg II absorption lines. We conclude that
J0823+2418 is likely a lensed quasar, and therefore that the VODKA sample
contains a population of these lensed systems (perhaps as high as 50%) as well
as dual quasars.
The search for dual supermassive black holes (SMBHs) is of immense interest in modern astrophysics. Galaxy mergers may be an important route to fuel and to produce SMBH pairs. Actively accreting SMBH ...pairs can be observed as a dual quasar, which are vital probes of SMBH growth. Gaia observations have enabled a novel technique to systematically search for such dual quasars at previously unreachable sub-kpc scales, based on the small jitters of the light centroid as the two quasars vary stochastically. Here we present the first detailed study of a 0.46'', 3.8 kpc separation, VODKA-selected dual quasar, J0749+2255, at \(z=2.17\) using JWST/NIRSpec integral field unit spectroscopy. This is one of the most distant, small separation dual quasars identified today. Dual quasars at cosmic noon are not well characterized. We detect the faint ionized gas of the host galaxy, best traced by the narrow \ha\ emission. Line ratio diagnostics show a mix of ionization from the two quasars and intense star formation. The spatially-resolved spectra of the two quasars suggest that they have very similar black hole properties (two \(M_{BH}\sim 10^9\ \textrm{M}_{\odot}\) with large Eddington ratio reaching \(L/L_{Edd}\sim0.2\)) hinting at the possible synchronized growth and accretion from the same gas supply. Surprisingly, the ionized gas kinematics suggest an extended, rotating disk rather than a disturbed system that would be expected in a major gas-rich galaxy merger. While it is unclear if J0749+2255 is representative of the dual quasar evolution, the observations with JWST revealed a major puzzle. It would be interesting to see what observations of other dual quasars will show.
Dual quasars, two active supermassive black holes at galactic scales, represent crucial objects for studying the impact of galaxy mergers and quasar activity on the star formation rate (SFR) within ...their host galaxies, particularly at cosmic noon when SFR peaks. We present JWST/MIRI mid-infrared integral field spectroscopy of J074922.96+225511.7, a dual quasar with a projected separation of 3.8 kilo-parsec at a redshift \(z\) of 2.17. We detect spatially extended Fe II 5.34\(\rm \mu\)m and polycyclic aromatic hydrocarbon (PAH) 3.3\(\mu\)m emissions from the star formation activity in its host galaxy. We derive the SFR of 10\(^{3.0\pm0.2}\) M\(_{\odot}\) yr\(^{-1}\) using PAH 3.3\(\mu\)m, which is five times higher than that derived from the cutoff luminosity of the infrared luminosity function for galaxies at \(z\sim2\). While the SFR of J0749+2255 agrees with that of star-forming galaxies of comparable stellar mass at the same redshifts, its molecular gas content falls short of expectations based on the molecular Kennicutt-Schmidt law. This discrepancy may result from molecular gas depletion due to the longer elevated stage of star formation, even after the molecular gas reservoir is depleted. We do not observe any quasar-driven outflow that impacts PAH and Fe II in the host galaxy based on the spatially resolved maps. From the expected flux in PAH-based star formation, the Fe II line likely originates from the star-forming regions in the host galaxy. Our study highlights the stardust nature of J0749+2255, indicating a potential connection between the dual quasar phase and intense star formation activities.
Four major genes in wheat (Triticum aestivum L.), with the dominant alleles designated Vrn-A1, Vrn-B1, Vrn-D1, and Vrn4, are known to have large effects on the vernalization response, but the effects ...on cold hardiness are ambiguous. Near-isogenic experimental lines (NILs) in a Triple Dirk (TD) genetic background with different vernalization alleles were evaluated for cold hardiness. Although TD is homozygous dominant for Vrn-A1 (formerly Vrn1) and Vrn-B1 (formerly Vrn2), four of the lines are each homozygous dominant for a different vernalization gene, and one line is homozygous recessive for all four vernalization genes. Following establishment, the plants were initially acclimated for 6 weeks in a growth chamber and then stressed in a low temperature freezer from which they were removed over a range of temperatures as the chamber temperature was lowered 1.3°C h-1. Temperatures resulting in no regrowth from 50% of the plants (LT50) were determined by estimating the inflection point of the sigmoidal response curve by nonlinear regression. The LT50 values were -6.7°C for cv. TD, -6.6°C for the Vrn-A1 and Vrn4 lines, -8.1°C for the Vrn-D1 (formerly Vrn3) line, -9.4°C for the Vrn-B1 line, and -11.7°C for the homozygous recessive winter line. The LT50 of the true winter line was significantly lower than those of all the other lines. Significant differences were also observed between some, but not all, of the lines possessing dominant vernalization alleles. The presence of dominant vernalization alleles at one of the four loci studied significantly reduced cold hardiness following acclimation.
Lyman continuum and line emission are thought to be important agents in the reionization of the early universe. Haro 11 is a rare example of a local galaxy in which Ly\(\alpha\) and continuum ...emission have escaped without being absorbed or scattered by ambient gas and dust, potentially as a consequence of feedback from its X-ray sources. We build on our previous Chandra analysis of Haro 11 by analyzing three new observations. Our subpixel spatial analysis reveals that the two previously known X-ray sources are each better modelled as ensembles of at least 2 unresolved point sources. The spatial variability of these components reveals X1 as a dynamical system where one luminous X-ray source (\(L_{\rm X} \sim 10^{41}\) erg s\(^{-1}\)) fades as a secondary source begins to flare. These might be intermediate mass black holes or low luminosity active galactic nuclei near the center of the galaxy in the process of merging. Optical emission line diagnostics drawn from the literature suggest that while the galaxy as a whole is consistent with starburst signatures of ionization, the individual regions wherein the X-ray sources reside are more consistent with AGN/composite classification. The sources in X2 exhibit some degree of flux variability. X2a dominates the flux of this region during most observations (\(L_{\rm X} \sim 6\ \times\ 10^{40}\) erg s\(^{-1}\)), and gives the only evidence in the galaxy of a soft Ultra-Luminous X-ray source capable of high energy winds, which we suggest are responsible for allowing the coincident Ly\(\alpha\) emission to escape.
In recent years, hydrodynamic optical-field-ionized (HOFI) channels have emerged as a promising technique to create laser waveguides suitable for guiding tightly-focused laser pulses in a plasma, as ...needed for laser-plasma accelerators. While experimental advances in HOFI channels continue to be made, the underlying mechanisms and the roles of the main parameters remain largely unexplored. In this work, we propose a start-to-end simulation pipeline of the HOFI channel formation and the resulting guiding properties, and use it to explore the underlying physics and the tunability of HOFI channels. This approach is benchmarked against experimental measurements. HOFI channels are shown to feature excellent guiding properties over a wide range of parameters, making them a promising and tunable waveguide option for laser-plasma accelerators.
We present a comparative study of active galactic nuclei (AGN) between galaxy pairs and isolated galaxies with the final data release of the MaNGA integral field spectroscopic survey. We build a ...sample of 391 kinematic galaxy pairs within the footprint of the survey and select AGN using the survey's spectra. We use the comoving volume densities of the AGN samples to quantify the effects that tidal interactions have on the triggering of nuclear accretion. Our hypothesis is that the pair sample contains AGN that are triggered by not only stochastic accretion but also tidally induced accretion and correlated accretion. With the level of stochastically triggered AGN fixed by the control sample, we model the strength of tidally induced accretion and correlated accretion as a function of projected separation (rp) and compare the model expectations with the observed volume densities of dual AGN and offset AGN (single AGN in a pair). At rp ~ 10 kpc, we find that tidal interactions induce ~30% more AGN than stochastic fueling and cause ~12% of the offset AGN to become dual AGN because of correlations. The strength of both these effects decreases with increasing rp. We also find that the OIII luminosities of the AGN in galaxy pairs are consistent with those found in isolated galaxies, likely because stochastically fed AGN dominate even among close pairs. Our results illustrates that while we can detect tidally induced effects statistically, it is challenging to separate tidally induced AGN and stochastically triggered AGN in interacting galaxies.
