Locally authored papers of the past 5 days

This is the list of the papers for the past 5 days that include local authors affiliated with Princeton University's Astrophysical Sciences department.

Papers with local authors from 2025-02-10

Andrew W. Howard, Evan Sinukoff, Sarah Blunt, Erik A. Petigura, Ian J. M. Crossfield, Howard Isaacson, Molly Kosiarek, Ryan A. Rubenzahl, John M. Brewer, Benjamin J. Fulton, Courtney D. Dressing, Lea A. Hirsch, Heather Knutson, John H. Livingston, Sean M. Mills, Arpita Roy, Lauren M. Weiss, Bjorn Benneke, David R. Ciardi, Jessie L. Christiansen, William D. Cochran, Justin R. Crepp, Erica Gonzales, Brad M. S. Hansen, Kevin Hardegree-Ullman, Steve B. Howell, Sébastien Lépine, Arturo O. Martinez, Leslie A. Rogers, Joshua E. Schlieder, Michael Werner, Alex S. Polanski, Isabel Angelo, Corey Beard, Aida Behmard, Luke G. Bouma, Casey L. Brinkman, Ashley Chontos, Fei Dai, Paul A. Dalba, Steven Giacalone, Samuel K. Grunblatt, Michelle L. Hill, Stephen R. Kane, Jack Lubin, Andrew W. Mayo, Teo Mocnik, Joseph M. Akana Murphy, Malena Rice, Lee J. Rosenthal, Dakotah Tyler, Judah Van Zandt, Samuel W. Yee
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Paper 7 — arXiv:2502.04436
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Paper 7 — arXiv:2502.04436

We report the masses, sizes, and orbital properties of 86 planets orbiting 55 stars observed by NASA's K2 Mission with follow-up Doppler measurements by the HIRES spectrometer at the W. M. Keck Observatory and the Automated Planet Finder at Lick Observatory. Eighty-one of the planets were discovered from their transits in the K2 photometry, while five were found based on subsequent Doppler measurements of transiting planet host stars. The sizes of the transiting planets range from Earth-size to larger than Jupiter (1-3 REarth is typical), while the orbital periods range from less than a day to a few months. For 32 of the planets, the Doppler signal was detected with significance greater than 5-sigma (51 were detected with >3-sigma significance). An important characteristic of this catalog is the use of uniform analysis procedures to determine stellar and planetary properties. This includes the transit search and fitting procedures applied to the K2 photometry, the Doppler fitting techniques applied to the radial velocities, and the spectral modeling to determine bulk stellar parameters. Such a uniform treatment will make the catalog useful for statistical studies of the masses, densities, and system architectures of exoplanetary systems. This work also serves as a data release for all previously unpublished RVs and associated stellar activity indicators obtained by our team for these systems, along with derived stellar and planet parameters.

Adam K. Leroy, Jiayi Sun, Sharon Meidt, Oscar Agertz, I-Da Chiang, Jindra Gensior, Simon C. O. Glover, Oleg Y. Gnedin, Annie Hughes, Eva Schinnerer, Ashley T. Barnes, Frank Bigiel, Alberto D. Bolatto, Dario Colombo, Jakob den Brok, Melanie Chevance, Ryan Chown, Cosima Eibensteiner, Damian R. Gleis, Kathryn Grasha, Jonathan D. Henshaw, Ralf S. Klessen, Eric W. Koch, Elias K. Oakes, Hsi-An Pan, Miguel Querejeta, Erik Rosolowsky, Toshiki Saito, Karin Sandstrom, Sumit K. Sarbadhicary, Yu-Hsuan Teng, Antonio Usero, Dyas Utomo, Thomas G. Williams

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Paper 18 — arXiv:2502.04481
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Paper 18 — arXiv:2502.04481

We compare measurements of star formation efficiency to cloud-scale gas properties across PHANGS-ALMA. Dividing 67 galaxies into 1.5 kpc scale regions, we calculate the molecular gas depletion time, tau_dep= Sigma_mol/Sigma_SFR, and the star formation efficiency per free-fall time, eff=tau_ff/tau_dep, for each region. Then we test how tau_dep and eff vary as functions of the regional mass-weighted mean molecular gas properties on cloud scales (60-150pc): gas surface density, <Sigma_mol^cloud>, velocity dispersion, <sigma_mol^cloud>, virial parameter, <alpha_vir^cloud>, and gravitational free-fall time, <tau_ff^cloud>. <tau_ff^cloud> and tau_dep correlate positively, consistent with the expectation that gas density plays a key role in setting the rate of star formation. Our fiducial measurements suggest tau_dep \propto <tau_ff^cloud>^0.5 and eff \approx 0.34%, though the exact numbers depend on the adopted fitting methods. We also observe anti-correlations between tau_dep and <Sigma_mol^cloud> and between tau_dep^mol and <sigma_mol^cloud> . All three correlations may reflect the same underlying link between density and star formation efficiency combined with systematic variations in the degree to which self-gravity binds molecular gas in galaxies. We highlight the tau_dep-<sigma_mol^cloud> relation because of the lower degree of correlation between the axes. Contrary to theoretical expectations, we observe an anti-correlation between tau_dep^mol and <alpha_vir^cloud> and no significant correlation between eff and <alpha_vir^cloud>. Our results depend sensitively on the adopted CO-to-H2 conversion factor, with corrections for excitation and emissivity effects in inner galaxies playing an important role. We emphasize that our simple methodology and clean selection allow easy comparison to numerical simulations and highlight this as a logical next direction.

Giorgio Manzoni, Tom Broadhurst, Jeremy Lim, Tao Liu, George Smoot, Carlton M. Baugh, Scott Tompkins, Rogier Windhorst, Simon Driver, Timothy Carleton, Brenda Frye, Leo Fung, Jiashuo Zhang, Seth H. Cohen, Christopher J. Conselice, Norman A. Grogin, Rolf A. Jansen, Anton M. Koekemoer, Rafael Ortiz III, Norbert Pirzkal, Christopher N. A. Willmer
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Paper 29 — arXiv:2502.04702
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Paper 29 — arXiv:2502.04702

A distinct power-law break is apparent m_AB approximately 21 in the deep Near-Infrared PEARLS-JWST galaxy counts. The break becomes more pronounced at longer wavelengths, with the counts slope flattening smoothly with apparent magnitude in the shortest band used at 0.9 microns, trending towards an increasingly broken slope by the longest wavelength passband of JWST NIRCam, 4.4 microns. This behaviour is remarkably well predicted by the GALFORM semi-analytical model of galaxy formation. We use the model to diagnose the origin of this behaviour. We find that the features that are responsible for the break are: 1) the inherent break in the luminosity function; 2) the change in the volume element with redshift and 3) the redshift-dependent nature of the k-correction. We study the contribution to these effects by early and late-type galaxies, using as a proxy for morphology the bulge-to-total stellar mass ratio. We find that the way in which ellipticals populate the bright end of the luminosity function while spirals dominate the faint end is preserved in the galaxy number counts, with a characteristic stellar mass at the break of approximately 10^10 M_sun. We also find that the shape of the number counts is mainly driven by galaxies with relatively low redshift (z < 2) for the PEARLS observational limit of m_AB < 28. We give a comprehensive description of why the galaxy number counts in the near-infrared PEARLS-JWST observation look the way they do and which population of galaxies is dominant at each apparent magnitude.

Zhen Cao, F. Aharonian, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, W. Bian, A.V. Bukevich, C.M. Cai, W.Y. Cao, Zhe Cao, J. Chang, J.F. Chang, A.M. Chen, E.S. Chen, H.X. Chen, Liang Chen, Long Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.B. Chen, X.J. Chen, Y. Chen, N. Cheng, Y.D. Cheng, M.C. Chu, M.Y. Cui, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, Danzengluobu, Y.X. Diao, X.Q. Dong, K.K. Duan, J.H. Fan, Y.Z. Fan, J. Fang, J.H. Fang, K. Fang, C.F. Feng, H. Feng, L. Feng, S.H. Feng, X.T. Feng, Y. Feng, Y.L. Feng, S. Gabici, B. Gao, C.D. Gao, Q. Gao, W. Gao, W.K. Gao, M.M. Ge, T.T. Ge, L.S. Geng, G. Giacinti, G.H. Gong, Q.B. Gou, M.H. Gu, F.L. Guo, J. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, O.A. Hannuksela, M. Hasan, H.H. He, H.N. He, J.Y. He, X.Y. He, Y. He, S. Hernández-Cadena, Y.K. Hor, B.W. Hou, C. Hou, X. Hou, H.B. Hu, S.C. Hu, C. Huang, D.H. Huang, J.J. Huang, T.Q. Huang, W.J. Huang, X.T. Huang, X.Y. Huang, Y. Huang, Y.Y. Huang, X.L. Ji, H.Y. Jia, K. Jia
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Paper 40 — arXiv:2502.04848
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Paper 40 — arXiv:2502.04848

The core-collapse supernova remnant (SNR) Cassiopeia A (Cas A) is one of the brightest galactic radio sources with an angular radius of $\sim$ 2.5 $\arcmin$. Although no extension of this source has been detected in the $\gamma$-ray band, using more than 1000 days of LHAASO data above $\sim 0.8$ TeV, we find that its spectrum is significantly softer than those obtained with Imaging Air Cherenkov Telescopes (IACTs) and its flux near $\sim 1$ TeV is about two times higher. In combination with analyses of more than 16 years of \textit{Fermi}-LAT data covering $0.1 \, \mathrm{GeV} - 1 \, \mathrm{TeV}$, we find that the spectrum above 30 GeV deviates significantly from a single power-law, and is best described by a smoothly broken power-law with a spectral index of $1.90 \pm 0.15_\mathrm{stat}$ ($3.41 \pm 0.19_\mathrm{stat}$) below (above) a break energy of $0.63 \pm 0.21_\mathrm{stat} \, \mathrm{TeV}$. Given differences in the angular resolution of LHAASO-WCDA and IACTs, TeV $\gamma$-ray emission detected with LHAASO may have a significant contribution from regions surrounding the SNR illuminated by particles accelerated earlier, which, however, are treated as background by IACTs. Detailed modelling can be used to constrain acceleration processes of TeV particles in the early stage of SNR evolution.

Papers with local authors from 2025-02-07

Hongrui Gu, Zhou Fan, Gang Zhao, Yang Huang, Timothy C. Beers, Wei Wang, Jie Zheng, Jingkun Zhao, Chun Li, Yuqin Chen, Haibo Yuan, Haining Li, Kefeng Tan, Yihan Song, Ali Luo, Nan Song, Yujuan Liu
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Paper 12 — arXiv:2502.03548
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Paper 12 — arXiv:2502.03548

Stellar parameters for large samples of stars play a crucial role in constraining the nature of stars and stellar populations in the Galaxy. An increasing number of medium-band photometric surveys are presently used in estimating stellar parameters. In this study, we present a machine-learning approach to derive estimates of stellar parameters, including [Fe/H], logg, and Teff, based on a combination of medium-band and broad-band photometric observations. Our analysis employs data primarily sourced from the SAGE Survey , which aims to observe much of the Northern Hemisphere. We combine the $uv$-band data from SAGES DR1 with photometric and astrometric data from Gaia EDR3, and apply the random forest method to estimate stellar parameters for approximately 21 million stars. We are able to obtain precisions of 0.09 dex for [Fe/H], 0.12 dex for logg, and 70 K for Teff. Furthermore, by incorporating 2MASS and WISE infrared photometric and GALEX ultraviolet data, we are able to achieve even higher precision estimates for over 2.2 million stars. These results are applicable to both giant and dwarf stars. Building upon this mapping, we construct a foundational dataset for research on metal-poor stars, the structure of the Milky Way, and beyond. With the forthcoming release of additional bands from SAGE Survey such DDO51 and H-alpha, this versatile machine learning approach is poised to play an important role in upcoming surveys featuring expanded filter sets

Papers with local authors from 2025-02-06

Valentin Mauerhofer, Pratika Dayal, Martin G. Haehnelt, Taysun Kimm, Joakim Rosdahl, Romain Teyssier
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Paper 12 — arXiv:2502.02647
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Paper 12 — arXiv:2502.02647

The field of high redshift galaxy formation has been revolutionised by JWST, which is yielding unprecedented insights on galaxy assembly at early times. Our key aim is to study the physical mechanisms that can explain the unexpected abundance of bright galaxies at $z \geq 11$, as well as their metal enrichment and spectral properties. We also use recent data to determine the key sources of reionisation. To do so, we implement cold gas fractions and star formation efficiencies derived from the SPHINX20 high-resolution radiation-hydrodynamics simulation into DELPHI, a semi-analytic model that tracks the assembly of dark matter halos and their baryonic components from $z \sim 4.5-40$. In addition, we explore two different methodologies to boost galaxy luminosities at $z \geq 11$: a stellar initial mass function (IMF) that becomes increasingly top-heavy with decreasing metallicity and increasing redshift (eIMF model), and star formation efficiencies that increase with increasing redshift (eSFE model). Our key findings are: (i) both the eIMF and eSFE models can explain the abundance of bright galaxies at $z \geq 11$; (ii) dust attenuation plays an important role for the bright-end of the UV LF at $z \leq 11$; (iii) the mass-metallicity relation is in place as early as $z \sim 17$ in all models although its slope is model-dependent; (iv) within the spread of both models and observations, all of our models are in good agreement with current estimates of $\beta$ slopes at $z \sim 5-17$ and Balmer break strengths at $z \sim 6-10$; (v) in the eIMF model, galaxies at $z\geq12$ or with $\rm{M_{UV}}\geq-18$ show values of $\xi_{\rm{ion}} \sim 10^{25.55}~{\rm [Hz~erg^{-1}]}$, twice larger than in other models; (vi) star formation in galaxies below $10^{9}\rm{M_{\odot}}$ is the key driver of reionisation, providing the bulk ($\sim 85\%$) of ionising photons down to its midpoint at $z \sim 7$.

Erin Kimbro, Vivienne Baldassare, Guy Worthey, Marla Geha, Jenny Greene
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Paper 21 — arXiv:2502.02751
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Paper 21 — arXiv:2502.02751

We analyze Hubble Space Telescope (HST) optical imaging of eight low-mass galaxies hosting active galactic nuclei (AGN) identified via their photometric variability in \cite{baldassare_search_2020}. We use GALFIT to model the 2D galaxy light profiles, and find a diversity of morphologies. The galaxies with regular morphologies are best fit with pseudo-bulges and disks, rather than classical bulges. We estimate black hole masses using scaling relations and find black hole masses of 10$^{3.7-6.6}$ M$_\odot$. We compare this sample to dwarf galaxies with AGN selected via optical spectroscopy. On average, the variable host galaxies have lower mass black holes. We analyze the brightest point source in each galaxy and find their properties are not entirely consistent with star clusters, indicating that they are likely AGN. These point sources are found to have lower luminosities than spectroscopically selected dwarf AGN, but brighter than the point sources in dwarf galaxies not identified as AGN. Our detailed imaging analysis shows that variability selection has the potential to find lower mass black holes and lower luminosity AGN than optical spectroscopy. These active dwarfs may have been missed by spectroscopic searches due to star formation dilution or low gas content.

Wei-Yang Wang, Xiaohui Liu, Dongzi Li, Bing Zhang, Chen-Hui Niu, Jifeng Liu, Renxin Xu, Weiwei Zhu
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Paper 25 — arXiv:2502.02857
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Paper 25 — arXiv:2502.02857

Frequency-dependent polarization properties provide crucial insights into the radiation mechanisms and magnetic environments of fast radio bursts (FRBs). We explore an analytical solution of radiative transfer of the polarization properties of FRBs as a strong incoming wave propagates in a homogeneous magnetized plasma. The case of a thermal plasma is studied in more detail. The rotational axis of the polarization spectrum undergoes precession with frequency on the Poincaré sphere when the medium has both strong Faraday rotation and conversion. Such precession on the Poincaré sphere could occur in hot or cold plasma with a strong magnetic field component perpendicular to the line of sight. The analytical solution with the mixing Faraday case offers a more physical description of the physical properties of the magnetic environment of FRBs than the empirical ``generalized Faraday rotation'' method commonly adopted in the literature. Significant absorption can exist in a dense plasma medium, which may give rise to a highly circularly polarized outgoing wave. The frequency-dependent Stokes parameters may be associated with reversing rotation measures or the presence of a persistent radio source around an FRB.

Oliver James White, Guifré Molera Calvés, Shinji Horiuchi, Jon Giorgini, Nick Stacy, Andrew Cole, Chris Phillips, Phil Edwards, Ed Kruzins, Jamie Stevens, Lance Benner, Edwin Peters
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Paper 27 — arXiv:2502.02890
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Paper 27 — arXiv:2502.02890

We detail the use of the University of Tasmania's (UTAS) optical and radio telescopes to conduct observations of near-Earth asteroids from 2021 to 2024. The Canberra Deep Space Communication Complex transmitted a radio signal at 7159.45 MHz, with the radar echo detected by the UTAS radio telescopes. The method of accounting for the Doppler shift between the stations and the near-Earth object is described so that others can implement a similar program. We present our results, with confirmed detections of 1994 PC1 and 2003 UC20 asteroids using the Hobart and Katherine 12-m antennas, demonstrating the feasibility of using small radio telescopes for these observations. Additionally, the recently upgraded Ceduna 30 m antenna was used to detect 2024 MK. Data collected from other observatories, such as Tidbinbilla, as well as the UTAS radar tracking of the moon are also presented in the context of demonstrating the means of applying these Doppler corrections and the accuracy of each method. Optical observations conducted in this period are also detailed as they complement radar observations and aid in refining the orbit parameters.

Papers with local authors from 2025-02-05

We use order of magnitude estimates and observational constraints to argue that feedback from relativistic cosmic rays (CRs) produced by massive black holes is likely to have a particularly large effect at radii of order the virial radius and larger in group-mass halos. We show that for a range of plausible (but uncertain) CR transport parameters and energetics, the pressure produced by CRs generated by the central massive black hole over its lifetime can be of order the thermal gas pressure in the outskirts of $\sim 10^{13-14} M_\odot$ halos (but not in more massive clusters). The properties of this CR feedback at low redshift are not well predicted by the radiative cooling rate of hot gas at smaller radii, which is often used as a proxy for `current' black hole feedback. This is because most black hole growth happens early in massive halos, and CR transport timescales in halo outskirts are Gyr or more; the accumulated CR energy thus depends on the full history of black hole activity in the halo. The large CR pressure in group-mass systems likely leads to CR-driven outflows that move gas from large halo radii to outside the virial radius. Such feedback would not be captured by current cosmological simulations that focus on mechanical black hole feedback; in particular, CR feedback remains active even long after the mechanical feedback sourcing the CRs has turned off. We speculate that this CR feedback may be important for explaining the weak lensing $S_8$ tension and the evidence for strong feedback at large halo radii from kinetic Sunyaev-Zeldovich measurements. Prospects for testing this mechanism observationally and implementing the necessary physics in cosmological simulations are discussed.

Xiao Cao, Yan-Mei Chen, Yong Shi, Junfeng Wang, Zhi-Jie Zhou, Min Bao, Qiusheng Gu, Alexei Moiseev, Luis C. Ho, Lan Wang, Guangquan Zeng
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Paper 31 — arXiv:2502.01921
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Paper 31 — arXiv:2502.01921

Dual active galactic nuclei (AGNs) with comparable masses are commonly witnessed among the major merged galaxies with interaction remnants. Considering almost every massive galaxy is associated with multiple dwarf satellites around it, minor mergers involving galaxies with disproportional stellar masses should be much more common than major mergers, which would naturally lead to black hole (BH) pairs with significantly different masses. However, dual AGNs generated by minor mergers involving one or two dwarf galaxies are exceptionally rare and understudied. Moreover, good estimates of the masses of both BHs are not yet available to test this idea. Here we report the evidence of a dual AGN candidate with mass ratio $\sim$7:1 located in an undisturbed disk galaxy. We identify the central BH with mass of $9.4 \times 10^6M_\odot$ from its radio emission as well as AGN-driven galactic-scale biconical outflows. The off-centered BH generates obvious broad and narrow emission-line regions, which gives us a robust estimation of a $1.3 \times 10^6M_\odot$ BH mass. We explore alternative scenarios for explaining the observational features of this system, including the complex gas kinematics triggered by central AGN activity and dust attenuation of the broad-line region of the central BH, finding that they failed to fully account for the kinematics of both the redshifted off-centered broad and narrow emission-line components.

Jeong Hwan Lee, Minjin Kim, Taehyun Kim, Hyunjin Shim, Luis C. Ho, Ho Seong Hwang, Hyunmi Song, Dohyeong Kim, Yujin Yang, Woong-Seob Jeong
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Paper 35 — arXiv:2502.01978
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Paper 35 — arXiv:2502.01978

The upcoming all-sky infrared spectrophotometric SPHEREx mission is set to provide spatially resolved stellar mass maps of nearby galaxies, offering more detailed insights than integrated light observations. In this study, we develop a strategy for estimating stellar mass using SPHEREx by examining the dependence on different stellar population synthesis (SPS) models and proposing new scaling relations based on simulated SPHEREx data. We estimate the resolved stellar masses of 19 nearby late-type galaxies from the PHANGS-MUSE survey, treating these as fiducial masses. By testing four SPS models covering infrared wavelengths, i.e., E-MILES, Bruzual \& Charlot 2003 (BC03), Charlot \& Bruzual 2019 (CB19), and FSPS, we find systematic differences in mass-to-light ratios at $3.6~{\rm \mu m}$ ($M_{\ast}/L_{\rm 3.6\mu m}$) among the SPS models. In particular, BC03 and CB19 yield mass-to-light ratios on average $\sim0.2-0.3~{\rm dex}$ lower than those from E-MILES and FSPS. These mass-to-light ratios strongly correlate with stellar age, indicating a significant impact of young stellar populations on stellar mass measurements. Our analysis, incorporating fiducial masses and simulated SPHEREx data, identifies the $1.6~{\rm \mu m}$ band as the optimal wavelength for stellar mass estimation, with the lowest scatter ($0.15-0.20~{\rm dex}$) of the stellar mass. This scatter can be further reduced to $0.10-0.12~{\rm dex}$ across all SPS models by incorporating optical and SPHEREx colors. These results can provide guidance for measuring the stellar masses of the numerous nearby galaxies that SPHEREx will survey.

Papers with local authors from 2025-02-04

Debosmita Pathak, Adam Leroy, Todd Thompson, Laura Lopez, Ashley Barnes, Daniel Dale, Ian Blackstone, Simon C. O. Glover, Shyam Menon, Jessica Sutter, Thomas Williams, Dalya Baron, Francesco Belfiore, Frank Bigiel, Alberto Bolatto, Mederic Boquien, Rupali Chandar, Mélanie Chevance, Ryan Chown, Kathryn Grasha, Brent Groves, Ralf Klessen, Kathryn Kreckel, Jing Li, José Méndez-Delgado, Erik W. Rosolowsky, Karin Sandstrom, Sumit Sarbadhicary, Jiayi Sun, Leonardo 'Ubeda
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Paper 16 — arXiv:2502.00165
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Paper 16 — arXiv:2502.00165

Radiation pressure is a key mechanism by which stellar feedback disrupts molecular clouds and drives HII region expansion. This includes direct radiation pressure exerted by UV photons on dust grains, pressure associated with photoionization, and infrared (IR) radiation pressure on grains due to dust-reprocessed IR photons. We present a new method that combines high resolution mid-IR luminosities from JWST-MIRI, optical attenuation and nebular line measurements from VLT-MUSE, and HST H$\alpha$-based region sizes to estimate the strength of radiation pressure in $\approx 18,000$ HII regions across 19 nearby star-forming galaxies. This is the most extensive and direct estimate of these terms beyond the Local Group to date. In the disks of galaxies, we find that the total reprocessed IR pressure is on average 5% of the direct UV radiation pressure. This fraction rises to 10% in galaxy centers. We expect reprocessed IR radiation pressure to dominate over UV radiation pressure in regions where $L_{\rm F2100W}/L_{\rm H\alpha}^{\rm corr} \gtrsim 75$. Radiation pressure due to H ionizations is lower than pressure on dust in our sample, but appears likely to dominate the radiation pressure budget in dwarf galaxies similar to the Small Magellanic Cloud. The contribution from all radiation pressure terms appears to be subdominant compared to thermal pressure from ionized gas, reinforcing the view that radiation pressure is most important in compact, heavily embedded, and young regions.

Interplanetary Coronal Mass Ejections (ICMEs) are the primary sources of geomagnetic storms at Earth. Negative out-of-ecliptic component (Bz) of magnetic field in the ICME or its associated sheath region is necessary for it to be geo-effective. For this reason, magnetohydrodynamic simulations of CMEs containing data-constrained flux ropes are more suitable for forecasting their geo-effectiveness as compared to hydrodynamic models of the CME. ICMEs observed in situ by radially aligned spacecraft can provide an important setup to validate the physics-based heliospheric modeling of CMEs. In this work, we use the constant-turn flux rope (CTFR) model to study an ICME that was observed in situ by Solar Orbiter (SolO) and at Earth, when they were in a near-radial alignment. This was a stealth CME that erupted on 2020 April 14 and reached Earth on 2020 April 20 with a weak shock and a smoothly rotating magnetic field signature. We found that the CTFR model was able to reproduce the rotating magnetic field signature at both SolO and Earth with very good accuracy. The simulated ICME arrived 5 hours late at SolO and 5 hours ahead at Earth, when compared to the observed ICME. We compare the propagation of the CME front through the inner heliosphere using synthetic J-maps and those observed in the heliospheric imager data and discuss the role of incorrect ambient SW background on kinematics of the simulated CME. This study supports the choice of the CTFR model for reproducing the magnetic field of ICMEs.

Sydney Vach, George Zhou, Andrew W. Mann, Madyson G. Barber, Tyler R. Fairnington, Chelsea X. Huang, James G. Rogers, Luke G. Bouma, Joachim Krüger, Duncan Wright, Annabelle E. Niblett, Jack M. Nelson, Stephanie T. Douglas, Samuel N. Quinn, David W. Latham, Allyson Bieryla, Karen A. Collins, Michelle Kunimoto, Cristilyn N. Watkins, Richard P. Schwarz, Kevin I. Collins, Ramotholo Sefako, Keith Horne, Steve B. Howell, Catherine A. Clark, Colin Littlefield, Jessie L. Christiansen, Zahra Essack, Joshua N. Winn
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Paper 37 — arXiv:2502.00576
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Paper 37 — arXiv:2502.00576

Measuring the properties of planets younger than about 50 Myr helps to test different planetary formation and evolution models. NASA's Transiting Exoplanet Survey Satellite (TESS) has observed nearly the entire sky, including a wide range of star-forming regions and young stellar clusters, expanding our census of the newborn planet population. In this work, we present the discovery of the TIC 88785435 planetary system located in the Upper-Centaurus Lupus (UCL) region of the Scorpius-Centaurus OB association (Sco-Cen) and a preliminary survey of the planet population within Sco-Cen. TIC 88785435 is a pre-main sequence, K7V dwarf ($M_\star = 0.72M_\odot$, $R_\star = 0.91R_\odot$, $T_\mathrm{eff}$ = 3998K, V = 11.7 mag) located within the bounds of UCL. We investigate the distribution of rotation periods measured from the TESS long-cadence data and the Halpha and Li abundances from the spectra of TIC 88785435. TESS long-candence data reveal that TIC 88785435 hosts a transiting super-Neptune ($R_b = 5.03R_\oplus$, P = 10.51 days), TIC 88785435 b. Ground-based follow-up validates the planetary nature of TIC 88785435 b. Using the TESS data, we perform a preliminary survey to investigate how TIC 88785435 b compares to the population of newly born planets located within Sco-Cen.

Jiangdan Li, Christian Wolf, Jiao Li, Yangping Luo, Jingkun Zhao, Bingqiu Chen, Lin Zhang, Shi Jia, Xuefei Chen, Zhanwen Han
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Paper 44 — arXiv:2502.00822
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Paper 44 — arXiv:2502.00822

The formation of compact binary systems is largely driven by their evolution through a common envelope (CE) phase, crucial for understanding phenomena such as type Ia supernovae and black hole mergers. Despite their importance, direct observational evidence for CE material has been elusive due to the transient nature of these envelopes. Numerical simulations suggest that some envelope material may persist post-ejection. In this study, we investigate circumstellar material (CSM) surrounding hot subdwarf (sdB) stars, focusing on material ejected during the CE phase of binary evolution. We analyze Ca II K absorption lines in 727 sdB candidates from the LAMOST-LRS survey, selecting 145 stars with strong absorption features, indicating the presence of CSM. We compare the velocities of the Ca II K lines with the systemic velocities of sdB binaries, confirming that the material originates from ejected common-envelope material. The results show that the CSM persists long after the CE event, suggesting the formation of a stable, long-lived circumstellar environment around sdB stars. This study enhances our understanding of the role of CSM in post-CE evolution and provides new insights into the physical processes shaping the evolution of sdB binaries.

Carlos Hervías-Caimapo, Kevin Wolz, Adrien La Posta, Susanna Azzoni, David Alonso, Kam Arnold, Carlo Baccigalupi, Simon Biquard, Michael L. Brown, Erminia Calabrese, Yuji Chinone, Samuel Day-Weiss, Jo Dunkley, Rolando Dünner, Josquin Errard, Giulio Fabbian, Ken Ganga, Serena Giardiello, Emilie Hertig, Kevin M. Huffenberger, Bradley R. Johnson, Baptiste Jost, Reijo Keskitalo, Theodore S. Kisner, Thibaut Louis, Magdy Morshed, Lyman A. Page, Christian L. Reichardt, Erik Rosenberg, Max Silva-Feaver, Wuhyun Sohn, Yoshinori Sueno, Dan B. Thomas, Ema Tsang King Sang, Amalia Villarrubia-Aguilar, Kyohei Yamada
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Paper 53 — arXiv:2502.00946
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Paper 53 — arXiv:2502.00946

We present a transfer function-based method to estimate angular power spectra from filtered maps for cosmic microwave background (CMB) surveys. This is especially relevant for experiments targeting the faint primordial gravitational wave signatures in CMB polarisation at large scales, such as the Simons Observatory (SO) small aperture telescopes. While timestreams can be filtered to mitigate the contamination from low-frequency noise, usual methods that calculate the mode coupling at individual multipoles can be challenging for experiments covering large sky areas or reaching few-arcminute resolution. The method we present here, although approximate, is more practical and faster for larger data volumes. We validate it through the use of simulated observations approximating the first year of SO data, going from half-wave plate-modulated timestreams to maps, and using simulations to estimate the mixing of polarisation modes induced by an example of time-domain filtering. We show its performance through an example null test and with an end-to-end pipeline that performs inference on cosmological parameters, including the tensor-to-scalar ratio $r$. The performance demonstration uses simulated observations at multiple frequency bands. We find that the method can recover unbiased parameters for our simulated noise levels.

Yaguang Li, Daniel Huber, J. M. Joel Ong, Jennifer van Saders, R. R. Costa, Jens Reersted Larsen, Sarbani Basu, Timothy R. Bedding, Fei Dai, Ashley Chontos, Theron W. Carmichael, Daniel Hey, Hans Kjeldsen, Marc Hon, Tiago L. Campante, Mário J. P. F. G. Monteiro, Mia Sloth Lundkvist, Nicholas Saunders, Howard Isaacson, Andrew W. Howard, Steven R. Gibson, Samuel Halverson, Kodi Rider, Arpita Roy, Ashley D. Baker, Jerry Edelstein, Chris Smith, Benjamin J. Fulton, Josh Walawender
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Paper 54 — arXiv:2502.00971
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Paper 54 — arXiv:2502.00971

We present the first asteroseismic analysis of the K3\,V planet host HD~219134, based on four consecutive nights of radial velocities collected with the Keck Planet Finder. We applied Gold deconvolution to the power spectrum to disentangle modes from sidelobes in the spectral window, and extracted 25 mode frequencies with spherical degrees $0\leq\ell\leq3$. We derive the fundamental properties using five different evolutionary-modeling pipelines and report a mass of 0.763 $\pm$ 0.020 (stat) $\pm$ 0.007 (sys) M$_\odot$, a radius of 0.748 $\pm$ 0.007 (stat) $\pm$ 0.002 (sys) R$_\odot$, and an age of 10.151 $\pm$ 1.520 (stat) $\pm$ 0.810 (sys) Gyr. Compared to the interferometric radius 0.783 $\pm$ 0.005~R$_\odot$, the asteroseismic radius is 4\% smaller at the 4-$\sigma$ level -- a discrepancy not easily explained by known interferometric systematics, modeling assumptions on atmospheric boundary conditions and mixing lengths, magnetic fields, or tidal heating. HD~219134 is the first main-sequence star cooler than 5000~K with an asteroseismic age estimate and will serve as a critical calibration point for stellar spin-down relations. We show that existing calibrated prescriptions for angular momentum loss, incorporating weakened magnetic braking with asteroseismically constrained stellar parameters, accurately reproduce the observed rotation period. Additionally, we revised the masses and radii of the super-Earths in the system, which support their having Earth-like compositions. Finally, we confirm that the oscillation amplitude in radial velocity scales as $(L/M)^{1.5}$ in K dwarfs, in contrast to the $(L/M)^{0.7}$ relation observed in G dwarfs. These findings provide significant insights into the structure and angular momentum loss of K-type stars.

Ying-Ying Gan, Su Yao, Tan-Zheng Wu, Hai-Ming Zhang, Jin Zhang
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Paper 60 — arXiv:2502.01115
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Paper 60 — arXiv:2502.01115

We present a comprehensive analysis of the X-ray observations obtained from \xmm\, and \chandra\, for a sample of bona-fide Compact Symmetric Objects (CSOs) to investigate their X-ray emission properties. Ultimately, we obtain 32 effective X-ray observational spectra from 17 CSOs. Most spectra can be well described by an absorbed single power-law model, with the exception of 6 spectra requiring an additional component in the soft X-ray band and 2 spectra exhibiting an iron emission line component. The data analysis results unveil the diverse characteristics of X-ray emission from CSOs. The sample covers X-ray luminosity ranging within $10^{40}-10^{45}$ erg s$^{-1}$, intrinsic absorbing column density ($N_{\rm H}^{\rm int}$) ranging within $10^{20}-10^{23}$ cm$^{-2}$, and photon spectral index ($\Gamma_{\rm X}$) ranging within 0.75--3.0. None of the CSOs in our sample have $N_{\rm H}^{\rm int}$ > $10^{23}\rm~cm^{-2}$, indicating that the X-ray emission in these CSOs is not highly obscured. The distribution of $\Gamma_{\rm X}$ for these CSOs closely resembles that observed in a sample of radio-loud quasars and low-excitation radio galaxies (RGs). In the radio--X-ray luminosity panel, these CSOs exhibit a distribution more akin to FR I RGs than FR II RGs, characterized by higher luminosities. The positive correlation between $\Gamma_{\rm X}$ and the Eddington ratio, which has been noted in radio-quiet active galactic nuclei, is not observed in these CSOs. These findings suggest that although the contribution of the disk-corona system cannot be completely ruled out, jet/lobe radiation likely plays a dominant role in the X-ray emission of these CSOs.