XAO OpenIR

Observational Study of Multiwavelength Synergistic Effects in 3C 120

Tue, 29 Sep 2026 10:16:56 GMT

Title: Observational Study of Multiwavelength Synergistic Effects in 3C 120 Authors: He, Yu-ting; Zhang, Ming; Yuan, Qi; Liao, Neng-hui Description: The energy dissipation and particle acceleration mechanisms within relativistic jets remain fundamental questions in active galactic nucleus research. In this paper, we present a comprehensive 13 yr (2012-2025) multiwavelength study of the broad-line radio galaxy 3C 120, utilizing Fermi Large Area Telescope (gamma rays), All-Sky Automated Survey for Supernovae (optical), and high-resolution Very Long Baseline Array (15 and 43 GHz) monitoring. Cross-correlation analyses reveal that gamma-ray flares lead radio emission by 11.08-1.88+4.03 months at 15 GHz and 8.27-5.55+3.45 months at 43 GHz. This frequency-dependent temporal hierarchy positions the high-energy dissipation zone upstream of the radio core, corroborating the opacity-driven core-shift effect. By tracking the parsec-scale jet morphology during major gamma-ray flaring epochs, we demonstrate that radio outbursts systematically coincide with compact core brightening, pronounced surges in polarized flux, abrupt electric vector position angle rotations, and the subsequent ejection of superluminal knots. Ultimately, our internal radio correlations suggest that jet dynamics are governed by a dual mechanism: long-term kinematic and flux baseline variations are geometrically modulated by a secular jet precession, while rapid, highly energetic polarimetric bursts are driven by short-lived internal shocks propagating down the jet channel.

Integrated geospatial and hydrological approach for modeling and forecasting to detect crop water stress in Laos

Tue, 29 Sep 2026 10:10:35 GMT

Title: Integrated geospatial and hydrological approach for modeling and forecasting to detect crop water stress in Laos Authors: Phommavong, Ketsana; Yan, Jianguo; Wang, Zhen; Chisenga, Chikondi Description: Climate change is a global threat as it exacerbates severe weather events and droughts, affecting food and water security. This study examines how rainfall, humidity, crop water losses, and the crop water stress index (CWSI) are changing in Laos from 2020 to 2022, focusing on trends caused by the monsoon and how droughts affect agriculture. Rainfall records indicate a delayed onset of the monsoon, with 55%-60% of the northern highlands receiving 1-10 mm at the start of the season, while the southern lowlands receive over 30 mm. In the main monsoon season, 60%-70% of Laos receives more than 50 mm of rainfall; however, the northern parts receive less rainfall due to topographical obstacles. Relative humidity varies between 40%-60% in winter and 50%-80% in spring, with greater fluctuations in 2022. Evapotranspiration is minimal (2-6 mm) in 60%-70% of the region during the dry seasons, while it increases in the southern areas with monsoon rainfall. The CWSI reaches a maximum value of 25% heavy load in May, corresponding with reduced soil moisture levels (similar to 190-200 mm) and negative soil moisture deficit index (SMDI) values. The research points to the importance of integrated drought monitoring for agricultural resilience in Laos.

The TOP-SCOPE Survey of Planck Galactic Cold Clumps: Molecular Gas Properties

Tue, 29 Sep 2026 10:04:13 GMT

Title: The TOP-SCOPE Survey of Planck Galactic Cold Clumps: Molecular Gas Properties Authors: Yuebin, Yang; Esimbek, Jarken; Liu, Tie; Baan, Willem; Liu, Xunchuan; Kim, Kee-Tae; Wu, Gang; Tang, Xindi; Zhou, Jianjun; Li, Dalei; He, Yuxin; Kang, Sung-Ju; Ma, Yingxiu; Zhou, Dongdong Description: We surveyed 2008 Planck Galactic Cold Clumps (PGCCs) in 12CO and 13CO J = 1-0 lines using the Taeduk Radio Astronomy Observatory 14 m telescope's multibeam receiver. We detected 2784 (12CO) and 2291 (13CO) velocity components, their closely correlated centroid velocities suggest that 12CO and 13CO generally trace kinematically associated gas. PGCCs have low excitation temperatures (mean similar to 10 K), mean 13CO optical depth similar to 0.5, and mean 13CO-derived H2 column density 4.3 & times; 1021 cm-2. Gas-dust correlations are moderate, with N13CO more tightly correlated with the dust-derived H2 column density from the PGCC catalog than I12CO . Colder PGCCs tend to have a higher CO-to-H2 conversion factor (XCO) and [H2]/[13CO] ratio. XCO increases clearly with the dust-derived H2 column density, consistent with enhanced CO freeze-out in high-column-density gas. Supersonic nonthermal motions are widespread: the Mach number derived from 13CO has a mean of 4.3 and a median of 3.6, increasing slightly with dust-derived H2 column density. Overall, PGCCs are cold but dynamically active, serving as a valuable laboratory for studying the initial conditions of star formation.

Tracking Protostellar Variability in Massive Protoclusters with ALMA. I. Insights from QUARKS and MaMMOtH (vol 1003, 60, 2026)

Tue, 29 Sep 2026 09:57:51 GMT

Title: Tracking Protostellar Variability in Massive Protoclusters with ALMA. I. Insights from QUARKS and MaMMOtH (vol 1003, 60, 2026) Authors: Yang, Yuhan; Liu, Tie; Liu, Sheng-Yuan; Johnstone, Doug; Herczeg, Gregory; Jiao, Wenyu; Su, Yu-Nung; Mai, Xiaofeng; Xu, Fengwei; Meyer, D. M. -A.; Zhang, Siju; Vorobyov, Eduard; Zhang, Suinan; Luo, Qiuyi; Garay, Guido; Chen, Xi; Jiao, Yunfan; Gu, Qilao; Zhang, Yankun; Tatematsu, Ken'ichi; Kim, Kee-Tae; Sobolev, Andrey M.; Parfenov, Sergey; Ladeyschikov, Dmitry A.; Bronfman, Leonardo

Direct VLBI evidence for a buried active galactic nucleus in the triple-merger luminous infrared galaxy UGC 2369S

Tue, 29 Sep 2026 09:51:30 GMT

Title: Direct VLBI evidence for a buried active galactic nucleus in the triple-merger luminous infrared galaxy UGC 2369S Authors: Xu, Wancheng; Frey, Sandor; Cui, Lang; Gabanyi, Krisztina Eva Description: Context. UGC 2369S is a luminous infrared galaxy (LIRG) undergoing a late-stage merger in a triple system, where the heavily obscured northern core is suspected to host an active galactic nucleus (AGN). However, severe dust and gas obscuration makes definitive confirmation challenging. Aims. We aim to provide direct observational evidence for the buried AGN through high-resolution radio imaging, while investigating the AGN accretion and feedback properties within this merger-driven gas-rich environment. Methods. We analyzed archival European VLBI Network (1.6 GHz) and Very Long Baseline Array (1.7 and 5 GHz) data of UGC 2369S. Through high-resolution imaging and visibility-domain Gaussian modeling, we characterized the morphology and intensity of its milliarcsecond-scale radio emission. Results. A compact radio component is detected in the northern core, exhibiting high brightness temperatures (T-b > 10(7) K) and a flat radio spectrum (alpha approximate to -0.45), which confirms the presence of an obscured AGN. The sub-Eddington accretion rate (lambda(Edd) approximate to 2.7 & times; 10(-4)) indicates that it falls within the radiatively inefficient accretion flow state. Conclusions. We provide direct imaging evidence for an AGN in the northern core of UGC 2369S, revealing a deeply buried, jet-emitting low-luminosity AGN enshrouded by a Compton-thick gas cocoon. This demonstrates that VLBI is a uniquely effective tool for disentangling nuclear accretion and feedback processes within the heavily obscured environments of multiple-merger systems.

A 44-min periodic radio transient in a supernova remnant

Tue, 29 Sep 2026 09:32:30 GMT

Title: A 44-min periodic radio transient in a supernova remnant Authors: Li, Di; Yuan, Mao; Wu, Lin; Yan, Jingye; Lv, Xuning; Tsai, Chaowei; Wang, Pei; Zhao, Jiaqi; Zhu, Weiwei; Deng, Li; Lan, Ailan; Xu, Renxin; Chen, Xianglei; Meng, Lingqi; Li, Jian; Li, Xiangdong; Zhou, Ping; Yang, Haoran; Xue, Mengyao; Lu, Jiguang; Miao, Chenchen; Wang, Weiyang; Niu, Jiarui; Fang, Ziyao; Fu, Qiuyang; Feng, Yi; Zhang, Peijing; Jiang, Jinchen; Miao, Xueli; Chen, Yu; Sun, Lingchen; Yang, Yang; Deng, Xiang; Dai, Shi; Chen, Xue; Yao, Jumei; Liu, Yujie; Li, Changheng; Zhang, Minglu; Yang, Yiwen; Zhou, Yucheng; Zhou, Yiyi; Zhang, Yongkun; Niu, Chenhui; Zhao, Rushuang; Zhang, Lei; Peng, Bo; Wu, Ji; Wang, Chi Description: Long-period radio transients (LPTs) are a newly discovered class of radio emitters with periods ranging from minutes to hours. The astrophysical nature remains undetermined, particularly of LPTs with no detectable companions. We report the first evidence for a plausible supernova remnant (SNR) association with an LPT (DART J1832-0911, 2656.23 +/- 0.15 s period), which supports a neutron star origin of such objects. The dispersion measure of this LPT, SNR's CO emission and neutral hydrogen (HI) absorption, and low probability of chance of alignment with field pulsars are all consistent with such an association. The source displays either phase-locked circular or nearly 100% linear polarization, indicating its strong and geometrically stable magnetic field. No detectable optical counterpart was found, even with a 10 mclass telescope. The SNR association and the stable polarization suggest that DART J1832-0911 most likely originates from a young neutron star, whose spin could have been braked by supernova's fallback materials. This discovery provides critical insights into the nature of ultra-long period transients and their link to stellar remnants. (c) 2026 The Authors. Published by Elsevier B.V. and Science China Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

SN 2021pfs: A type Ia supernova likely affected by progenitor metallicity, as revealed by comparison with its twin counterpart

Tue, 29 Sep 2026 09:32:27 GMT

Title: SN 2021pfs: A type Ia supernova likely affected by progenitor metallicity, as revealed by comparison with its twin counterpart Authors: Iskandar, Abdusamatjan; Wang, Xiaofeng; Esamdin, Ali; Li, Wenxiong; Zeng, Xiangyun; Huang, Ruifeng; Hu, Maokai; Lu, Guoliang; Howell, D. Andrew; McCully, Curtis; Wyatt, Samuel; Hiramatsu, Daichi; Gonzalez, Estefania Padilla; Pellegrino, Craig; Newsome, Megan; Galbany, Lluis; Sand, David J.; Smith, Nathan; Sears, Huei Description: We present extensive photometric and spectroscopic observations of the normal type Ia supernovae (SNe Ia) 2021pfs, which occurred in the Seyfert 2 galaxy NGC 5427 at a redshift of 0.009. SN 2021pfs reached an absolute B-band peak magnitude of M-max(B) =-19.28 +/- 0.40 mag and a post-peak decline rate of Delta m(15)(B) =1.13 +/- 0.06 mag. The observed properties of this nearby SN Ia closely resemble those of SN 2011fe, including the main optical spectroscopic features and photometric evolution. Despite their similar decline rates, SN 2021pfs rose more rapidly in the U band but more slowly in the r and i bands compared to SN 2011fe in very early phases. This photometric difference, particularly at short wavelengths, can introduce a systematic uncertainty of up to similar to 12% in distance estimates. Analysis of the host galaxy's local and global environment shows an environment consistent with producing a higher-metallicity progenitor for SN 2021pfs than that of SN 2011fe. This higher progenitor metallicity may explain the observed photometric discrepancy and the resulting distance between SN 2021pfs and SN 2011fe, though a larger sample of such "twin" SNe Ia is needed to confirm this trend and assess its impact on cosmological measurements.

Evolution of Starless Cores in Massive Clumps Seen by the ALMA ASHES and QUARKS Surveys

Tue, 29 Sep 2026 09:32:24 GMT

Title: Evolution of Starless Cores in Massive Clumps Seen by the ALMA ASHES and QUARKS Surveys Authors: Yang, Dongting; Liu, Hong-li; Qin, Sheng-li; Liu, Tie; Jiao, Wenyu; Garay, Guido; Sanhueza, Patricio; Xu, Fengwei; Zhu, Lei; Dib, Sami; Tang, Xindi; Stutz, Amelia; Mai, Xiaofeng; Zhang, Siju; Yang, A. Y.; Tej, Anandmayee; Li, Shanghuo; Liu, Xunchuan; Garcia, Pablo; Juvela, Mika; Chibueze, James O.; Gorai, Prasanta; Kim, Kee-tae; Lee, Chang Won; Baug, Tapas; Das, Swagat Ranjan; Gupta, Shivani; Hwang, Jihye; Bronfman, Leonardo; Soam, Archana; Dewangan, L. K. Description: We present a systematic comparative analysis of 324 starless cores in early-phase infrared-dark clouds (IRDCs; ASHES survey) and evolved-phase infrared-bright clouds (IRBCs; QUARKS survey) using 1.3 mm continuum and line data by the Atacama Large Millimeter/submillimeter Array. Despite having comparable sizes (similar to 2500 au), starless cores in IRBCs exhibit systematically higher median mass (1.5 M circle dot versus 0.6 M circle dot), number density, and surface density-enhancements of approximately a factor of 2 relative to starless cores in IRDCs. Starless cores in IRBCs also display relatively stronger nonthermal motions (sigma similar to 0.5 km s-1 versus 0.3 km s-1), higher total virial parameters (median alpha vir,tot similar to 2.3 versus 1.0), and steeper density profiles, indicating more centrally concentrated structures in feedback-driven, turbulence-enhanced environments. These findings support a dual evolutionary origin: (i) new core formation in evolved IRBCs under altered initial conditions and (ii) subsequent dynamical mass growth via accretion from extended reservoirs. The prevalence of low-mass starless cores-even in late-stage IRBC environments-challenges models requiring massive prestellar cores and instead favors competitive-like dynamical mass accretion scenarios for high-mass star formation.

A molecule-rich torus-like structure in the 21 μm source IRAS 23304+6147 (vol. 696, A102, 2025)

Tue, 29 Sep 2026 09:32:22 GMT

Title: A molecule-rich torus-like structure in the 21 μm source IRAS 23304+6147 (vol. 696, A102, 2025) Authors: Sun, Hao-Min; Zhang, Yong; Ouyang, Xu-Jia; Qin, Sheng-Li; Nakashima, Junichi; Qiu, Jian-Jie; Li, Xiao-Hu

EP250827b/SN 2025wkm: An X-Ray Flash-supernova Powered by a Central Engine and Circumstellar Interaction

Tue, 29 Sep 2026 09:32:18 GMT

Title: EP250827b/SN 2025wkm: An X-Ray Flash-supernova Powered by a Central Engine and Circumstellar Interaction Authors: Srinivasaragavan, Gokul P.; Li, Dongyue; Hall, Xander J.; Gottlieb, Ore; Schroeder, Genevieve; Liu, Heyang; O'Connor, Brendan; Jin, Chichuan; Kasliwal, Mansi; Ahumada, Tomas; Wu, Qinyu; Fryer, Christopher L.; Niblett, Annabelle E.; Xu, Dong; Ravasio, Maria Edvige; Daja, Grace; Li, Wenxiong; Anand, Shreya; Ho, Anna Y. Q.; Sun, Hui; Perley, Daniel A.; Yan, Lin; Burns, Eric; Cenko, S. Bradley; Sollerman, Jesper; Sarin, Nikhil; Piro, Anthony L.; Aryan, Amar; Miller, M. Coleman; An, Jie; An, Tao; Andrews, Moira; Augustin, Jule; Bellm, Eric C.; Bochenek, Aleksandra; Busmann, Malte; Chanchaiworawit, Krittapas; Cheng, Huaqing; Caballero-Garcia, Maria D.; Castro-Tirado, Alberto J.; Esamdin, Ali; Faba-Moreno, Jennifer; Farah, Joseph; Fernandez-Garcia, Emilio; Fu, Shaoyu; Fynbo, Johan P. U.; Gassert, Julius; Padilla Gonzalez, Estefania; Perez-Garcia, Ignacio; Graham, Matthew; Gritsevich, Maria; Gruen, Daniel; Guziy, Sergiy; He, Linbo; Howell, D. Andrew; Hu, Jingwei; Hu, You-Dong; Iskandar, Abdusamatjan; Jaimes, Joahan Castaneda; Jiang, Ji-An; Jiang, Ning; Jiang, Shuaiqing; Liang, Runduo; Ling, Zhixing; Liu, Jialian; Liu, Xing; Liu, Yuan; Masci, Frank J.; McCully, Curtis; Newsome, Megan; Noysena, Kanthanakorn; B. Pandey, Shashi; Ni, Kangrui; Palmese, Antonella; Peng, Han-Long; Purdum, Josiah; Qin, Yu-Jing; Rose, Sam; Rusholme, Ben; Sanchez-Ramirez, Ruben; Sevilla, Cassie; Smith, Roger; Song, Yujia; Sravan, Niharika; Stein, Robert; Tabor, Constantin; Terreran, Giacomo; Tinyanont, Samaporn; Vega, Pablo; Wang, Letian; Waing, Tinggui; Wang, Xiaofeng; Wu, Siyu; Wu, Xuefeng; Wynn, Kathryn; Xu, Yunfei; Yan, Shengyu; Yuan, Weimin; Zhang, Binbin; Zhang, Chen; Zhu, Zipei; Zuo, Xiaoxiong; Bhullar, Gursimran Description: We present the discovery of EP250827b/SN 2025wkm, an X-ray flash (XRF) discovered by the Einstein Probe (EP), accompanied by a broad-line Type Ic supernova (SN Ic-BL) at z = 0.1194. EP250827b possesses a prompt X-ray luminosity of similar to 10(45) erg s(-1), lasts over 1000 s, and has a peak energy E-p < 1.5 keV at 90% confidence. SN 2025wkm possesses a double-peaked optical light curve (LC), though its bolometric luminosity plateaus after its initial peak for similar to 20 days, consistent with a central engine injecting additional energy into the explosion. Its spectrum transitions from a blue to red continuum with clear blueshifted broad absorption features consistent with a SN Ic-BL classification. We do not detect any transient radio emission and rule out the existence of an on-axis, energetic jet greater than or similar to 10(50) erg assuming a typical LGRB circumburst constant density (n approximate to 10(-3)-10(-1) cm(-3)) and microphysical parameters (& varepsilon;(e) = 0.1 and & varepsilon;(B) = 0.01). In the model we invoke, the collapse gives rise to a long-lived magnetar, potentially surrounded by an accretion disk. Magnetically driven winds from the magnetar and the disk mix together and break out with a velocity similar to 0.35c and interact with an extended circumstellar medium with radius similar to 10(13) cm, generating X-ray breakout emission through nonthermal free-free processes. The disk outflows and magnetar winds power blackbody photospheric emission as they cool adiabatically and thermalize, producing the first SN peak. The spin-down luminosity of the magnetar and radioactive decay of Ni-56 power the late-time emission. We end by discussing the landscape of XRF-SNe within the context of EP's recent discoveries.