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1. Measuring the Variance of the Macquart Relation in Redshift–Extragalactic Dispersion Measure Modeling

   https://doi.org/10.3847/1538-4357/ad2705  

   Baptista, Jay ; Prochaska, J. Xavier ; Mannings, Alexandra G. ; James, C. W. ; Shannon, R. M. ; Ryder, Stuart D. ; Deller, A. T. ; Scott, Danica R. ; Glowacki, Marcin ; Tejos, Nicolas ( April 2024 , The Astrophysical Journal)

   The Macquart relation describes the correlation between the dispersion measure (DM) of fast radio bursts (FRBs) and the redshiftzof their host galaxies. The scatter of the Macquart relation is sensitive to the distribution of baryons in the intergalactic medium including those ejected from galactic halos through feedback processes. The variance of the distribution in DMs from the cosmic web (DM_cosmic) is parameterized by a fluctuation parameterF. In this work, we present a new measurement ofFusing 78 FRBs of which 21 have been localized to host galaxies. Our analysis simultaneously fits for the Hubble constantH₀and the DM distribution due to the FRB host galaxy. We find that the fluctuation parameter is degenerate with these parameters, most notablyH₀, and use a uniform prior onH₀to measure${\log }_{10}F>-0.86$at the 3σconfidence interval and a new constraint on the Hubble constant$H_0={85.3}_{-8.1}^{+9.4}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$. Using a synthetic sample of 100 localized FRBs, the constraint on the fluctuation parameter is improved by a factor of ∼2. Comparing ourFmeasurement to simulated predictions from cosmological simulation (IllustrisTNG), we find agreement between redshifts 0.4 <z andz< 2.0. However, atz< 0.4, the simulations underpredictF, which we attribute to the rapidly changing extragalactic DM excess distribution at low redshift.

    

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2. The FRB 20190520B Sight Line Intersects Foreground Galaxy Clusters

   https://doi.org/10.3847/2041-8213/acefb5  

   Lee, Khee-Gan ; Khrykin, Ilya S. ; Simha, Sunil ; Ata, Metin ; Huang, Yuxin ; Prochaska, J. Xavier ; Tejos, Nicolas ; Cooke, Jeff ; Nagamine, Kentaro ; Zhang, Jielai ( August 2023 , The Astrophysical Journal Letters)

   The repeating fast radio burst FRB 20190520B is an anomaly of the FRB population thanks to its high dispersion measure (DM = 1205 pc cm⁻³) despite its low redshift ofz_frb= 0.241. This excess has been attributed to a large host contribution of DM_host≈ 900 pc cm⁻³, far larger than any other known FRB. In this paper, we describe spectroscopic observations of the FRB 20190520B field obtained as part of the FLIMFLAM survey, which yielded 701 galaxy redshifts in the field. We find multiple foreground galaxy groups and clusters, for which we then estimated halo masses by comparing their richness with numerical simulations. We discover two separateM_halo> 10¹⁴M_⊙galaxy clusters atz= 0.1867 and 0.2170 that are directly intersected by the FRB sight line within their characteristic halo radiusr₂₀₀. Subtracting off their estimated DM contributions, as well that of the diffuse intergalactic medium, we estimate a host contribution of${\mathrm{D}\mathrm{M}}_{\mathrm{h}\mathrm{o}\mathrm{s}\mathrm{t}}={430}_{-220}^{+140}$or${280}_{-170}^{+140}\mathrm{p}\mathrm{c}{\mathrm{c}\mathrm{m}}^{-3}$(observed frame), depending on whether we assume that the halo gas extends tor₂₀₀or 2 ×r₂₀₀. This significantly smaller DM_host—no longer the largest known value—is now consistent with Hαemission measures of the host galaxy without invoking unusually high gas temperatures. Combined with the observed FRB scattering timescale, we estimate the turbulent fluctuation and geometric amplification factor of the scattering layer to be$\tilde{F}G\approx 4.5–11{({\mathrm{pc}}^2\mathrm{km})}^{-1/3}$, suggesting that most of the gas is close to the FRB host. This result illustrates the importance of incorporating foreground data for FRB analyses both for understanding the nature of FRBs and to realize their potential as a cosmological probe.

    

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3. Formation and evolution of post-solitons following a high intensity laser-plasma interaction with a low-density foam target

   https://doi.org/10.1088/1361-6587/abf85c  

   Blackman, David R. ; Adak, Amitava ; Singh, Prashant K. ; Lad, Amit D. ; Chatterjee, Gourab ; Ridgers, Christopher P. ; Del Sorbo, Dario ; Trines, Raoul M. G. M. ; Robinson, A. P. L. ; Nazarov, Wigen ; et al ( May 2021 , Plasma Physics and Controlled Fusion)

   The formation and evolution of post-solitons has been discussed for quite some time both analytically and through the use of particle-in-cell (PIC) codes. It is however only recently that they have been directly observed in laser-plasma experiments. Relativistic electromagnetic (EM) solitons are localised structures that can occur in collisionless plasmas. They consist of a low-frequency EM wave trapped in a low electron number-density cavity surrounded by a shell with a higher electron number-density. Here we describe the results of an experiment in which a 100 TW Ti:sapphire laser (30 fs, 800 nm) irradiates a$0.03\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$TMPTA foam target with a focused intensity$I_{\mathrm{l}}=9.5\times {10}^{17}\mathrm{W}\mathrm{c}{\mathrm{m}}^{-2}$. A third harmonic (${\lambda }_{\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{b}\mathrm{e}}\simeq 266$nm) probe is employed to diagnose plasma motion for 25 ps after the main pulse interaction via Doppler-Spectroscopy. Both radiation-hydrodynamics and 2D PIC simulations are performed to aid in the interpretation of the experimental results. We show that the rapid motion of the probe critical-surface observed in the experiment might be a signature of post-soliton wall motion.

    

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4. The EDGE-CALIFA Survey: Spatially Resolved 13 CO(1–0) Observations and Variations in 12 CO(1–0)/ 13 CO(1–0) in Nearby Galaxies on Kiloparsec Scales

   https://doi.org/10.3847/1538-4365/acd840  

   Cao, Yixian ; Wong, Tony ; Bolatto, Alberto D. ; Leroy, Adam K. ; Rosolowsky, Erik ; Utomo, Dyas ; Sánchez, Sebastián F. ; Barrera-Ballesteros, Jorge K. ; Levy, Rebecca C. ; Colombo, Dario ; et al ( August 2023 , The Astrophysical Journal Supplement Series)

   We present¹³CO(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${\mathit{}}_{12/13}\equiv I{[}^{12}\mathrm{CO}(J=1\to 0)]/I{[}^{13}\mathrm{CO}(J=1\to 0)]$and the properties of the stars and ionized gas. Higher${\mathit{}}_{12/13}$values are found in interacting galaxies compared to those in noninteracting galaxies. The global${\mathit{}}_{12/13}$slightly increases with infrared colorF₆₀/F₁₀₀but appears insensitive to other host-galaxy properties such as morphology, stellar mass, or galaxy size. We also present azimuthally averaged${\mathit{}}_{12/13}$profiles for our sample up to a galactocentric radius of 0.4r₂₅(∼6 kpc), taking into account the¹³CO nondetections by spectral stacking. The radial profiles of${\mathit{}}_{12/13}$are quite flat across our sample. Within galactocentric distances of 0.2r₂₅, the azimuthally averaged${\mathit{}}_{12/13}$increases with the star formation rate. However, Spearman rank correlation tests show the azimuthally averaged${\mathit{}}_{12/13}$does not strongly correlate with any other gas or stellar properties in general, especially beyond 0.2r₂₅from the galaxy centers. Our findings suggest that in the complex environments in galaxy disks,${\mathit{}}_{12/13}$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${\mathit{}}_{12/13}$, which further complicates the interpretations of${\mathit{}}_{12/13}$variations.

    

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5. Deciphering the sensitivity of urban canopy air temperature to anthropogenic heat flux with a forcing-feedback framework

   https://doi.org/10.1088/1748-9326/ace7e0  

   Wang, Linying ; Sun, Ting ; Zhou, Wenyu ; Liu, Maofeng ; Li, Dan ( August 2023 , Environmental Research Letters)

   The sensitivity of urban canopy air temperature ($T_a$) to anthropogenic heat flux ($Q_{AH}$) is known to vary with space and time, but the key factors controlling such spatiotemporal variabilities remain elusive. To quantify the contributions of different physical processes to the magnitude and variability of$\mathrm{\Delta }{T}_a/\mathrm{\Delta }{Q}_{AH}$(where$\mathrm{\Delta }$represents a change), we develop a forcing-feedback framework based on the energy budget of air within the urban canopy layer and apply it to diagnosing$\mathrm{\Delta }{T}_a/\mathrm{\Delta }{Q}_{AH}$simulated by the Community Land Model Urban over the contiguous United States (CONUS). In summer, the median$\mathrm{\Delta }{T}_a/\mathrm{\Delta }{Q}_{AH}$is around 0.01$\text{K\hspace{0.17em}}{\left(\text{W\hspace{0.17em}}{\text{m}}^{-\text{2}}\right)}^{-1}$over the CONUS. Besides the direct effect of$Q_{AH}$on$T_a$, there are important feedbacks through changes in the surface temperature, the atmosphere–canopy air heat conductance ($c_a$), and the surface–canopy air heat conductance. The positive and negative feedbacks nearly cancel each other out and$\mathrm{\Delta }{T}_a/\mathrm{\Delta }{Q}_{AH}$is mostly controlled by the direct effect in summer. In winter,$\mathrm{\Delta }{T}_a/\mathrm{\Delta }{Q}_{AH}$becomes stronger, with the median value increased by about 20% due to weakened negative feedback associated with$c_a$. The spatial and temporal (both seasonal and diurnal) variability of$\mathrm{\Delta }{T}_a/\mathrm{\Delta }{Q}_{AH}$as well as the nonlinear response of$\mathrm{\Delta }{T}_a$to$\mathrm{\Delta }{Q}_{AH}$are strongly related to the variability of$c_a$, highlighting the importance of correctly parameterizing convective heat transfer in urban canopy models.

    

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