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97 results on '"Dai, P F"'

1. An Intermediate-mass Black Hole Lurking in A Galactic Halo Caught Alive during Outburst

Author

Jin, C. -C., Li, D. -Y., Jiang, N., Dai, L. -X., Cheng, H. -Q., Zhu, J. -Z., Yang, C. -W., Rau, A., Baldini, P., Wang, T. -G., Zhou, H. -Y., Yuan, W., Zhang, C., Shu, X. -W., Shen, R. -F., Wang, Y. -L., Wen, S. -X., Wu, Q. -Y., Wang, Y. -B., Thomsen, L. L., Zhang, Z. -J., Zhang, W. -J., Coleiro, A., Eyles-Ferris, R., Fang, X., Ho, L. C., Hu, J. -W., Jin, J. -J., Li, W. -X., Liu, B. -F., Liu, F. -K., Liu, M. -J., Liu, Z., Lu, Y. -J., Merloni, A., Qiao, E. -L., Saxton, R., Soria, R., Wang, S., Xue, Y. -Q., Yang, H. -N., Zhang, B., Zhang, W. -D., Cai, Z. -M., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -H., Chen, Y. -F., Chen, Y., Cordier, B., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Ding, H. -C., Fan, D. -W., Fan, Z., Feng, H., Garcia, J. A., Guan, J., Han, D. -W., Hou, D. -J., Hu, H. -B., Huang, M. -H., Huo, J., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, G., Kong, X., Kuulkers, E., Lei, W. -H., Li, C. -K., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Lian, T. -Y., Ling, Z. -X., Liu, C. -Z., Liu, H. -Y, Liu, H. -Q., Liu, J. -F., Liu, Y., Lu, F. -J., Luo, L. -D., Ma, J., Mao, X., Mu, H. -Y., Nandra, K., O'Brien, P., Pan, H. -W., Pan, X., Qin, G. -J., Rea, N., Sanders, J., Song, L. -M., Sun, H., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Wang, B. -C., Wang, J., Wang, J. -F., Wang, L., Wang, W. -X., Wang, Y. -S., Wang, Z. -X., Wu, Q. -W., Wu, X. -F., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, S. -J., Xue, Y. -L., Yan, A. -L., Yang, X. -T., Yang, Y. -J., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zheng, J., Zhu, Q. -F., Zhu, Y. -X., Zhu, Z. -C., and Zou, H.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

Stellar-mass and supermassive black holes abound in the Universe, whereas intermediate-mass black holes (IMBHs) of ~10^2-10^5 solar masses in between are largely missing observationally, with few cases found only. Here we report the real-time discovery of a long-duration X-ray transient, EP240222a, accompanied by an optical flare with prominent H and He emission lines revealed by prompt follow-up observations. Its observed properties evidence an IMBH located unambiguously in the halo of a nearby galaxy and flaring by tidally disrupting a star -- the only confirmed off-nucleus IMBH-tidal disruption event so far. This work demonstrates the potential of sensitive time-domain X-ray surveys, complemented by timely multi-wavelength follow-ups, in probing IMBHs, their environments, demographics, origins and connections to stellar-mass and supermassive black holes., Comment: 64 pages, 15 figures, submitted

Published
2025

2. Extragalactic fast X-ray transient from a weak relativistic jet associated with a Type Ic-BL supernova

Author

Sun, H., Li, W. -X., Liu, L. -D., Gao, H., Wang, X. -F., Yuan, W., Zhang, B., Filippenko, A. V., Xu, D., An, T., Ai, S., Brink, T. G., Liu, Y., Liu, Y. -Q., Wang, C. -Y., Wu, Q. -Y., Wu, X. -F., Yang, Y., Zhang, B. -B., Zheng, W. -K., Ahumada, T., Dai, Z. -G., Delaunay, J., Elias-Rosa, N., Benetti, S., Fu, S. -Y., Howell, D. A., Huang, Y. -F., Kasliwal, M. M., Karambelkar, V., Stein, R., Lei, W. -H., Lian, T. -Y., Peng, Z. -K., Ridnaia, A. V., Svinkin, D. S., Wang, X. -Y., Wang, A. -L., Wei, D. -M., An, J., Andrews, M., Bai, J. -M, Dai, C. -Y., Ehgamberdiev, S. A., Fan, Z., Farah, J., Feng, H. -C., Fynbo, J. P. U., Guo, W. -J., Guo, Z., Hu, M. -K., Hu, J. -W., Jiang, S. -Q., Jin, J. -J., Li, A., Li, J. -D., Li, R. -Z., Liang, Y. -F., Ling, Z. -X., Liu, X., Mao, J. -R., McCully, C., Mirzaqulov, D., Newsome, M., Gonzalez, E. Padilla, Pan, X., Terreran, G., Tinyanont, S., Wang, B. -T., Wang, L. -Z., Wen, X. -D., Xiang, D. -F., Xue, S. -J., Yang, J., Zhu, Z. -P., Cai, Z. -M., Castro-Tirado, A. J., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -H., Chen, Y. -F., Chen, Y., Cheng, H. -Q., Cordier, B., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Fan, D. -W., Feng, H., Guan, J., Han, D. -W., Hou, D. -J., Hu, H. -B., Huang, M. -H., Huo, J., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Kuulkers, E., Li, C. -K., Li, D. -Y., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Liu, C. -Z, Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Lu, F. -J., Luo, L. -D., Ma, J., Mao, X., Nandra, K., O'Brien, P., Pan, H. -W., Rau, A., Rea, N., Sanders, J., Song, L. -M., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, Y. -L., Wang, Y. -S., Xiong, D. -R., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, H. -N., Yang, X. -T., Yang, Y. -J., Zhang, C., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, Y. -L., Zhu, Y. -X., and Zhu, Z. -C.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Massive stars end their life as core-collapse supernovae, amongst which some extremes are Type Ic broad-lined supernovae associated with long-duration gamma-ray bursts (LGRBs) having powerful relativistic jets. Their less-extreme brethren make unsuccessful jets that are choked inside the stars, appearing as X-ray flashes or low-luminosity GRBs. On the other hand, there exists a population of extragalactic fast X-ray transients (EFXTs) with timescales ranging from seconds to thousands of seconds, whose origins remain obscure. Known sources that contribute to the observed EFXT population include the softer analogs of LGRBs, shock breakouts of supernovae, or unsuccessful jets. Here, we report the discovery of the bright X-ray transient EP240414a detected by the Einstein Probe (EP), which is associated with the Type Ic supernova SN 2024gsa at a redshift of 0.401. The X-ray emission evolution is characterised by a very soft energy spectrum peaking at < 1.3 keV, which makes it distinct from known LGRBs, X-ray flashes, or low-luminosity GRBs. Follow-up observations at optical and radio bands revealed the existence of a weak relativistic jet that interacts with an extended shell surrounding the progenitor star. Located on the outskirts of a massive galaxy, this event reveals a new population of explosions of Wolf-Rayet stars characterised by a less powerful engine that drives a successful but weak jet, possibly owing to a progenitor star with a smaller core angular momentum than in traditional LGRB progenitors., Comment: 43 pages, 9 figures, 4 tables, submitted. Comments are welcome

Published
2024

3. Soft X-ray prompt emission from the high-redshift gamma-ray burst EP240315a

Author

Liu, Y., Sun, H., Xu, D., Svinkin, D. S., Delaunay, J., Tanvir, N. R., Gao, H., Zhang, C., Chen, Y., Wu, X.-F., Zhang, B., Yuan, W., An, J., Bruni, G., Frederiks, D. D., Ghirlanda, G., Hu, J.-W., Li, A., Li, C.-K., Li, J.-D., Malesani, D. B., Piro, L., Raman, G., Ricci, R., Troja, E., Vergani, S. D., Wu, Q.-Y., Yang, J., Zhang, B.-B., Zhu, Z.-P., de Ugarte Postigo, A., Demin, A. G., Dobie, D., Fan, Z., Fu, S.-Y., Fynbo, J. P. U., Geng, J.-J., Gianfagna, G., Hu, Y.-D., Huang, Y.-F., Jiang, S.-Q., Jonker, P. G., Julakanti, Y., Kennea, J. A., Kokomov, A. A., Kuulkers, E., Lei, W.-H., Leung, J. K., Levan, A. J., Li, D.-Y., Li, Y., Littlefair, S. P., Liu, X., Lysenko, A. L., Ma, Y.-N., Martin-Carrillo, A., O’Brien, P., Parsotan, T., Quirola-Vásquez, J., Ridnaia, A. V., Ronchini, S., Rossi, A., Mata-Sánchez, D., Schneider, B., Shen, R.-F., Thakur, A. L., Tohuvavohu, A., Torres, M. A. P., Tsvetkova, A. E., Ulanov, M. V., Wei, J.-J., Xiao, D., Yin, Y.-H. I., Bai, M., Burwitz, V., Cai, Z.-M., Chen, F.-S., Chen, H.-L., Chen, T.-X., Chen, W., Chen, Y.-F., Chen, Y.-H., Cheng, H.-Q., Cordier, B., Cui, C.-Z., Cui, W.-W., Dai, Y.-F., Dai, Z.-G., Eder, J., Eyles-Ferris, R. A. J., Fan, D.-W., Feldman, C., Feng, H., Feng, Z., Friedrich, P., Gao, X., Gonzalez, J.-F., Guan, J., Han, D.-W, Han, J., Hou, D.-J., Hu, H.-B., Hu, T., Huang, M.-H., Huo, J., Hutchinson, I., Ji, Z., Jia, S.-M., Jia, Z.-Q., Jiang, B.-W., Jin, C.-C., Jin, G., Jin, J.-J., Keereman, A., Lerman, H., Li, J.-F., Li, L.-H., Li, M.-S., Li, W., Li, Z.-D., Lian, T.-Y., Liang, E.-W., Ling, Z.-X., Liu, C.-Z., Liu, H.-Y., Liu, H.-Q., Liu, M.-J., Liu, Y.-R., Lu, F.-J., Lü, H.-J., Luo, L.-D., Ma, F. L., Ma, J., Mao, J.-R., Mao, X., McHugh, M., Meidinger, N., Nandra, K., Osborne, J. P., Pan, H.-W., Pan, X., Ravasio, M. E., Rau, A., Rea, N., Rehman, U., Sanders, J., Santovincenzo, A., Song, L.-M., Su, J., Sun, L.-J., Sun, S.-L., Sun, X.-J., Tan, Y.-Y., Tang, Q.-J., Tao, Y.-H., Tong, J.-Z., Wang, C.-Y., Wang, H., Wang, J., Wang, L., Wang, W.-X., Wang, X.-F., Wang, X.-Y., Wang, Y.-L., Wang, Y.-S., Wei, D.-M., Willingale, R., Xiong, S.-L., Xu, H.-T., Xu, J.-J., Xu, X.-P., Xu, Y.-F., Xu, Z., Xue, C.-B., Xue, Y.-L., Yan, A.-L., Yang, F., Yang, H.-N., Yang, X.-T., Yang, Y.-J, Yu, Y.-W., Zhang, J., Zhang, M., Zhang, S.-N., Zhang, W.-D., Zhang, W.-J., Zhang, Y.-H., Zhang, Z., Zhang, Z., Zhang, Z.-L., Zhao, D.-H., Zhao, H.-S., Zhao, X.-F., Zhao, Z.-J., Zhou, L.-X., Zhou, Y.-L., Zhu, Y.-X., Zhu, Z.-C., and Zuo, X.-X.

Published
2025
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4. Soft X-ray prompt emission from a high-redshift gamma-ray burst EP240315a

Author

Liu, Y., Sun, H., Xu, D., Svinkin, D. S., Delaunay, J., Tanvir, N. R., Gao, H., Zhang, C., Chen, Y., Wu, X. -F., Zhang, B., Yuan, W., An, J., Bruni, G., Frederiks, D. D., Ghirlanda, G., Hu, J. -W., Li, A., Li, C. -K., Li, J. -D., Malesani, D. B., Piro, L., Raman, G., Ricci, R., Troja, E., Vergani, S. D., Wu, Q. -Y., Yang, J., Zhang, B. -B., Zhu, Z. -P., Postigo, A. de Ugarte, Demin, A. G., Dobie, D., Fan, Z., Fu, S. -Y., Fynbo, J. P. U., Geng, J. -J., Gianfagna, G., Hu, Y. -D., Huang, Y. -F., Jiang, S. -Q., Jonker, P. G., Julakanti, Y., Kennea, J. A., Kokomov, A. A., Kuulkers, E., Lei, W. -H., Leung, J. K., Levan, A. J., Li, D. -Y., Li, Y., Littlefair, S. P., Liu, X., Lysenko, A. L., Ma, Y. -N., Martin-Carrillo, A., O'Brien, P., Parsotan, T., Quirola-Vasquez, J., Ridnaia, A. V., Ronchini, S., Rossi, A., Mata-Sanchez, D., Schneider, B., Shen, R. -F., Thakur, A. L., Tohuvavohu, A., Torres, M. A. P., Tsvetkova, A. E., Ulanov, M. V., Wei, J. -J., Xiao, D., Yin, Y. -H. I., Bai, M., Burwitz, V., Cai, Z. -M., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -F., Chen, Y. -H., Cheng, H. -Q., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Dai, Z. -G., Eder, J., Fan, D. -W., Feldman, C., Feng, H., Feng, Z., Friedrich, P., Gao, X., Guan, J., Han, D. -W, Han, J., Hou, D. -J., Hu, H. -B., Hu, T., Huang, M. -H., Huo, J., Hutchinson, I., Ji, Z., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Jin, J. -J., Keereman, A., Lerman, H., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Lian, T. -Y., Liang, E. -W., Ling, Z. -X., Liu, C. -Z., Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Liu, Y. -R., Lu, F. -J., LU, H. -J., Luo, L. -D., Ma, F. L., Ma, J., Mao, J. -R., Mao, X., McHugh, M., Meidinger, N., Nandra, K., Osborne, J. P., Pan, H. -W., Pan, X., Ravasio, M. E., Rau, A., Rea, N., Rehman, U., Sanders, J., Santovincenzo, A., Song, L. -M., Su, J., Sun, L. -J., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Tong, J. -Z., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, X. -F., Wang, X. -Y., Wang, Y. -L., Wang, Y. -S., Wei, D. -M., Willingale, R., Xiong, S. -L., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, F., Yang, H. -N., Yang, X. -T., Yang, Y. -J, Yu, Y. -W., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, L. -X., Zhou, Y. -L., Zhu, Y. -X., Zhu, Z. -C., and Zuo, X. -X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Long gamma-ray bursts (GRBs) are believed to originate from core collapse of massive stars. High-redshift GRBs can probe the star formation and reionization history of the early universe, but their detection remains rare. Here we report the detection of a GRB triggered in the 0.5--4 keV band by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated as EP240315a, whose bright peak was also detected by the Swift Burst Alert Telescope and Konus-Wind through off-line analyses. At a redshift of $z=4.859$, EP240315a showed a much longer and more complicated light curve in the soft X-ray band than in gamma-rays. Benefiting from a large field-of-view ($\sim$3600 deg$^2$) and a high sensitivity, EP-WXT captured the earlier engine activation and extended late engine activity through a continuous detection. With a peak X-ray flux at the faint end of previously known high-$z$ GRBs, the detection of EP240315a demonstrates the great potential for EP to study the early universe via GRBs., Comment: 41 pages, 8 figures, 7 tables

Published
2024

5. The Lobster Eye Imager for Astronomy Onboard the SATech-01 Satellite

Author

Ling, Z. X., Sun, X. J., Zhang, C., Sun, S. L., Jin, G., Zhang, S. N., Zhang, X. F., Chang, J. B., Chen, F. S., Chen, Y. F., Cheng, Z. W., Fu, W., Han, Y. X., Li, H., Li, J. F., Li, Y., Li, Z. D., Liu, P. R., Lv, Y. H., Ma, X. H., Tang, Y. J., Wang, C. B., Xie, R. J., Xue, Y. L., Yan, A. L., Zhang, Q., Bao, C. Y., Cai, H. B., Cheng, H. Q., Cui, C. Z., Dai, Y. F., Fan, D. W., Hu, H. B., Hu, J. W., Huang, M. H., Jia, Z. Q., Jin, C. C., Li, D. Y., Li, J. Q., Liu, H. Y., Liu, M. J., Liu, Y., Pan, H. W., Qiu, Y. L., Sugizaki, M., Sun, H., Wang, W. X., Wang, Y. L., Wu, Q. Y., Xu, X. P., Xu, Y. F., Yang, H. N., Yang, X., Zhang, B., Zhang, M., Zhang, W. D., Zhang, Z., Zhao, D. H., Cong, X. Q., Jiang, B. W., Li, L. H., Qiu, X. B., Sun, J. N., Su, D. T., Wang, J., Wu, C., Xu, Z., Yang, X. M., Zhang, S. K., Zhang, N., Zhu, Y. F., Ban, H. Y., Bi, X. Z., Cai, Z. M., Chen, W., Chen, X., Chen, Y. H., Cui, Y., Duan, X. L., Feng, Z. G, Gao, Y., He, J. W., He, T., Huang, J. J., Li, F., Li, J. S., Li, T. J., Li, T. T., Liu, H. Q., Liu, L., Liu, R., Liu, S., Meng, N., Shi, Q., Sun, A. T., Wang, Y. M., Wang, Y. B., Wu, H. C., Xu, D. X, Yang, Y. Q, Yang, Y., Yu, X. S., Zhang, K. X., Zhang, Y. L., Zhang, Y. H., Zhang, Y. T., Zhou, H., Zhu, X. C., Cheng, J. S., Qin, L., Wang, L., Wang, Q. L., Bai, M., Gao, R. L., Ji, Z., Liu, Y. R., Ma, F. L., Shi, Y. J., Su, J., Tan, Y. Y., Tong, J. Z., Xu, H. T., Xue, C. B., Xue, G. F., and Yuan, W.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

The Lobster Eye Imager for Astronomy (LEIA), a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe (EP) mission, was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on 27 July 2022. In this paper, we introduce the design and on-ground test results of the LEIA instrument. Using state-of-the-art Micro-Pore Optics (MPO), a wide field-of-view (FoV) of 346 square degrees (18.6 degrees * 18.6 degrees) of the X-ray imager is realized. An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons, and four large-format complementary metal-oxide semiconductor (CMOS) sensors, each of 6 cm * 6 cm, are used as the focal plane detectors. The instrument has an angular resolution of 4 - 8 arcmin (in FWHM) for the central focal spot of the point spread function, and an effective area of 2 - 3 cm2 at 1 keV in essentially all the directions within the field of view. The detection passband is 0.5 - 4 keV in the soft X-rays and the sensitivity is 2 - 3 * 10-11 erg s-1 cm-2 (about 1 mini-Crab) at 1,000 second observation. The total weight of LEIA is 56 kg and the power is 85 W. The satellite, with a design lifetime of 2 years, operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes. LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation, and by optimizing the working setups of the instrumental parameters. In addition, LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band, albeit limited useful observing time available., Comment: Accepted by RAA

Published
2023
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6. First wide field-of-view X-ray observations by a lobster eye focusing telescope in orbit

Author

Zhang, C., Ling, Z. X., Sun, X. J., Sun, S. L., Liu, Y., Li, Z. D., Xue, Y. L., Chen, Y. F., Dai, Y. F., Jia, Z. Q., Liu, H. Y., Zhang, X. F., Zhang, Y. H., Zhang, S. N., Chen, F. S., Cheng, Z. W., Fu, W., Han, Y. X., Li, H., Li, J. F., Li, Y., Liu, P. R., Ma, X. H., Tang, Y. J., Wang, C. B., Xie, R. J., Yan, A. L., Zhang, Q., Jiang, B. W., Jin, G., Li, L. H., Qiu, X. B., Su, D. T., Sun, J. N., Xu, Z., Zhang, S. K., Zhang, Z., Zhang, N., Bi, X. Z., Cai, Z. M., He, J. W., Liu, H. Q., Zhu, X. C., Cheng, H. Q., Cui, C. Z., Fan, D. W., Hu, H. B., Huang, M. H., Jin, C. C., Li, D. Y., Pan, H. W., Wang, W. X., Xu, Y. F., Yang, X., Zhang, B., Zhang, M., Zhang, W. D., Zhao, D. H., Bai, M., Ji, Z., Liu, Y. R., Ma, F. L., Su, J., Tong, J. Z., Wang, Y. S., Zhao, Z. J., Feldman, C., O'Brien, P., Osborne, J. P., Willingale, R., Burwitz, V., Hartner, G., Langmeier, A., Müller, T., Rukdee, S., Schmidt, T., Kuulkers, E., and Yuan, W.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

As a novel X-ray focusing technology, lobster eye micro-pore optics (MPO) feature both a wide observing field of view and true imaging capability, promising sky monitoring with significantly improved sensitivity and spatial resolution in soft X-rays. Since first proposed by Angel (1979), the optics have been extensively studied, developed and trialed over the past decades. In this Letter, we report on the first-light results from a flight experiment of the Lobster Eye Imager for Astronomy ($LEIA$), a pathfinder of the wide-field X-ray telescope of the Einstein Probe mission. The piggyback imager, launched in July 2022, has a mostly un-vignetted field of view of $18.6^\circ \times 18.6^\circ $. Its spatial resolution is in the range of 4$-$7 arcmin in FWHM and the focal spot effective area is 2$-$3 cm$^2$, both showing only mild fluctuations across the field of view. We present images of the Galactic center region, Sco X-1 and the diffuse Cygnus Loop nebular taken in snapshot observations over 0.5$-$4 keV. These are truly wide-field X-ray images of celestial bodies observed, for the first time, by a focusing imaging telescope. Initial analyses of the in-flight data show excellent agreement between the observed images and the on-ground calibration and simulations. The instrument and its characterization are briefly described, as well as the flight experiment. The results provide a solid basis for the development of the present and proposed wide-field X-ray missions using lobster eye MPO., Comment: 11 pages, 4 figures. Accepted for publication in Astrophysical Journal Letter

Published
2022
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7. Quantum Critical Magnetic Excitations in Spin-1/2 and Spin-1 Chain Systems

Author

Xu, Y., Wang, L. S., Huang, Y. Y., Ni, J. M., Zhao, C. C., Dai, Y. F., Pan, B. Y., Hong, X. C., Chauhan, P., Koohpayeh, S. M., Armitage, N. P., and Li, S. Y.

Subjects
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science, Condensed Matter - Superconductivity
Abstract

The study of CoNb$_2$O$_6$ sits at the confluence of simplicity and complexity: on one hand, the model for Ising chains -- the building blocks of CoNb$_2$O$_6$ -- in a transverse field, can be exactly solved and, thus, serves as an archetype of quantum criticality; on the other hand, the weak but nonzero interchain coupling adds geometric frustration to the stage, substantially complicating the phase diagram. Here we utilize low-temperature specific heat and thermal conductivity measurements to study the low-lying magnetic excitations in CoNb$_2$O$_6$ and its spin-1 analogue NiNb$_2$O$_6$. The thermal conductivity is found to be suppressed around the quantum critical point, where the specific heat is enhanced due to gapless magnetic excitations, pointing to the localized nature of the latter. These results highlight the predominant role of frustration in determining the quantum critical magnetic excitations of spin chains, which may furthermore underlie the remarkable similarities between the phenomenology of these spin-1/2 and spin-1 systems., Comment: 9 pages, 3 figures

Published
2021

8. Robust nodal superconductivity induced by isovalent doping in Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ and BaFe$_2$(As$_{1-x}$P$_x$)$_2$

Author

Qiu, X., Zhou, S. Y., Zhang, H., Pan, B. Y., Hong, X. C., Dai, Y. F., Eom, Man Jin, Kim, Jun Sung, Ye, Z. R., Zhang, Y., Feng, D. L., and Li, S. Y.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

We present the ultra-low-temperature heat transport study of iron-based superconductors Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ and BaFe$_2$(As$_{1-x}$P$_x$)$_2$. For optimally doped Ba(Fe$_{0.64}$Ru$_{0.36}$)$_2$As$_2$, a large residual linear term $\kappa_0/T$ at zero field and a $\sqrt{H}$ dependence of $\kappa_0(H)/T$ are observed, which provide strong evidences for nodes in the superconducting gap. This result demonstrates that the isovalent Ru doping can also induce nodal superconductivity, as P does in BaFe$_2$(As$_{0.67}$P$_{0.33}$)$_2$. Furthermore, in underdoped Ba(Fe$_{0.77}$Ru$_{0.23}$)$_2$As$_2$ and heavily underdoped BaFe$_2$(As$_{0.82}$P$_{0.18}$)$_2$, $\kappa_0/T$ manifests similar nodal behavior, which shows the robustness of nodal superconductivity in the underdoped regime and puts constraint on theoretical models., Comment: 5 pages, 4 figures - with two underdoped samples added, this paper supersedes arXiv:1106.5417

Published
2011

9. Nodal superconductivity in Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ induced by isovalent Ru substitution

Author

Qiu, X., Zhou, S. Y., Zhang, H., Pan, B. Y., Hong, X. C., Dai, Y. F., Eom, Man Jin, Kim, Jun Sung, and Li, S. Y.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

We present the ultra-low-temperature heat transport study of an iron-based superconductor Ba(Fe$_{0.64}$Ru$_{0.36}$)$_2$As$_2$ ($T_c$ = 20.2 K), in which the superconductivity is induced by isovalent Ru substitution. In zero field we find a large residual linear term $\kappa_0/T$, more than 40% of the normal-state value. At low field, the $\kappa_0/T$ shows an $H^{1/2}$ dependence. These provide strong evidences for nodes in the superconducting gap of Ba(Fe$_{0.64}$Ru$_{0.36}$)$_2$As$_2$, which mimics that in another isovalently substituted superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$. Our results show that the isovalent Ru substitution can also induce nodal superconductivity in BaFe$_2$As$_2$, as P does, and they may have the same origin. We further compare them with other two nodal superconductors LaFePO and LiFeP., Comment: 4 pages, 4 figures

Published
2011

10. Unveiling the quantum critical point of an Ising chain

Author

Dai, Y. F., Zhang, H., Zhou, S. Y., Pan, B. Y., Qiu, X., Hong, X. C., Guan, T. Y., Dong, J. K., Chen, Y., and Li, S. Y.

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

Quantum phase transitions occur at zero temperature upon variation of some nonthermal control parameters. The Ising chain in a transverse field is probably the most-studied model undergoing such a transition, from ferromagnetic to paramagnetic state1,2. This model can be exactly solved by using a Jordan-Wigner transformation, which transforms the spins into noninteracting spinless fermions1. At the quantum critical point, the magnetic excitations can carry arbitrarily low energy and dominate the low temperature properties. Here we report the unveiling of such quantum critical point in quasi-one-dimensional Ising ferromagnet CoNb2O6 by ultra-low-temperature thermal conductivity measurements. We find that in the paramagnetic state, phonons are scattered by the magnetic excitations above certain temperature Ts, which corresponds to a gap. As predicted by the theoretical model1, this gap linearly goes to zero with decreasing the transverse field, thus determining the quantum critical point of the Ising chain., Comment: 14 pages, 3 figures

Published
2011

11. Field-induced quantum critical point and nodal superconductivity in the heavy-fermion superconductor Ce2PdIn8

Author

Dong, J. K., Zhang, H., Qiu, X., Pan, B. Y., Dai, Y. F., Guan, T. Y., Zhou, S. Y., Gnida, D., Kaczorowski, D., and Li, S. Y.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

The interplay between magnetism and superconductivity has been a central issue in unconventional superconductors. While the dynamic magnetism could be the source of electron pairing, the static magnetism is generally believed to compete with superconductivity. In this sense, the observation of Q phase, the coupled spin-density wave order and superconductivity, in the heavy-fermion superconductor CeCoIn5 is very puzzling. Whether this Q phase origins from the novel Fulde-Ferrel-Larkin-Ovchinnikov state is under hot debate. Here we report the resistivity and thermal conductivity study of a newly discovered heavy-fermion superconductor Ce2PdIn8 down to 50 mK. We find an unusual field-induced quantum critical point at the upper critical field Hc2 and unconventional nodal superconductivity in Ce2PdIn8. The jump of thermal conductivity k(H)/T near Hc2 suggests a first-order-like phase transition at low temperatures. These results mimic the features of the Q phase in CeCoIn5, implying that Ce2PdIn8 is another promising compound to investigate the exotic Q phase and FFLO state. The comparison between CeCoIn5 and Ce2PdIn8 may help to clarify the origin of the Q phase., Comment: 18 pages, 4 figures

Published
2010

12. Reply to comment by T. Terashima et al. on 'Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe$_2$As$_2$'

Author

Dong, J. K., Zhou, S. Y., Guan, T. Y., Zhang, H., Dai, Y. F., Qiu, X., Wang, X. F., He, Y., Chen, X. H., and Li, S. Y.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

Reply to comment by T. Terashima et al. on "Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe$_2$As$_2$", Comment: 1 page, 1 figure, to appear in Phys. Rev. Lett

Published
2010

13. Quantum criticality and nodal superconductivity in the FeAs-based superconductor KFe2As2

Author

Dong, J. K., Zhou, S. Y., Guan, T. Y., Zhang, H., Dai, Y. F., Qiu, X., Wang, X. F., He, Y., Chen, X. H., and Li, S. Y.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

The in-plane resistivity $\rho$ and thermal conductivity $\kappa$ of FeAs-based superconductor KFe$_2$As$_2$ single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior $\rho(T) \sim T^{1.5}$ at $H_{c_2}$ = 5 T, and the development of a Fermi liquid state with $\rho(T) \sim T^2$ when further increasing field. This suggests a field-induced quantum critical point, occurring at the superconducting upper critical field $H_{c_2}$. In zero field there is a large residual linear term $\kappa_0/T$, and the field dependence of $\kappa_0/T$ mimics that in d-wave cuprate superconductors. This indicates that the superconducting gaps in KFe$_2$As$_2$ have nodes, likely d-wave symmetry. Such a nodal superconductivity is attributed to the antiferromagnetic spin fluctuations near the quantum critical point., Comment: 4 pages, 4 figures - replaces arXiv:0909.4855

Published
2009
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14. Thermal conductivity study of KFe$_2$As$_2$ single crystal: clear evidence for unconventional superconducting gap with nodes

Author

Dong, J. K., Zhou, S. Y., Guan, T. Y., Zhang, H., Dai, Y. F., Qiu, X., Wang, X. F., He, Y., Chen, X. H., and Li, S. Y.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

The in-plane resistivity $\rho$ and thermal conductivity $\kappa$ of extremely overdoped KFe$_2$As$_2$ ($T_c$ = 3.0 K) single crystal were studied. It is found that $\rho \sim T^{1.5}$ at low temperature, a typical non-Fermi liquid behavior of electrons scattered by antiferromagnetic spin fluctuations. In zero field, we observed a large residual linear term $\kappa_0/T$, about one third of the normal-state value. In low magnetic fields, $\kappa_0/T(H)$ increases very fast. Such a behavior of $\kappa_0/T$ mimics the d-wave cuprate superconductors, therefore provides clear evidence for nodes in the superconducting gap of KFe$_2$As$_2$. Based on the Fermi surface topology of KFe$_2$As$_2$, it is believed that the dominant intraband pairing via antiferromagnetic spin fluctuations results in the unconventional superconducting gap with nodes., Comment: This paper is replaced by arXiv:0910.2806, which includes a detailed study of the quantum criticality in KFe2As2. The paper arXiv:0910.2806 supersedes this paper

Published
2009

15. Universal condition for the existence of interface modes in the whole momentum space with arbitrary materials

Author

Dong, J. W., Zeng, J., Dai, Q. F., and Wang, H. Z.

Subjects
Physics - Optics
Abstract

It is shown that, by theoretical and experimental results, a universal zero-impedance condition exists for two kinds of localized interface modes in the whole momentum space (both above and below the light line). It can be applied at the interface between any two materials including photonic crystals, single-negative (negative-permittivity or negative-permeability) materials, or double-negative metamaterials. In addition, it presents an intuitive physical concept, and also provides a feasible way to determine interface modes, which will have predominance in various applications., Comment: 19 pages, 5 figures

Published
2008

24. Misconceptions about the Moon Held by Preservice Teachers in Taiwan.

Author

Dai, Meme F. and Capie, William

Abstract

The objective of this study was to assess the misconceptions held by preservice teachers about essential concepts of the moon related to information taught in elementary schools in Taiwan and to develop multiple-choice test items to identify the misconceptions about the moon. Additionally, this study considered relationships of gender, religion, and science major to misconceptions about the moon. The lack of preparation preservice teachers receive in astronomy is identified and ways of enhancing the earth science teacher training curriculum are suggested. Instrument development, identification of misconceptions, results, effective instructional models, and teaching strategies are discussed. (KR)

Published
1990

48. LINC00958/miR-3174/PHF6 axis is responsible for triggering proliferation, migration and invasion of endometrial cancer.

Author

LI, Q.-Y., SHEN, J.-Q., LI, J.-H., DAI, D.-F., SAEED, M., and LI, C.-X.

Abstract

OBJECTIVE: To reveal the role of LINC00958 in the progression of endometrial cancer (EC) and the underlying molecular mechanism. PATIENTS AND METHODS: Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was conducted to detect relative level of LINC00958 in EC specimens and cell lines. Its prognostic potential in EC was analyzed by Kaplan-Meier method. After in vitro knockdown of LINC00958, cell proliferative, migratory and invasive abilities in KLE and Ishikawa cells were evaluated by Cell Counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU) and transwell assay. Dual-Luciferase reporter assay was carried out to identify the LINC00958/miR-3174/PHF6 axis, and their expression interaction was determined by Pearson correlation test. The role of miR-3174 in influencing LINC00958-induced phenotype changes of EC cells was determined through rescue experiments. RESULTS: LINC00958 was abnormally upregulated in EC specimens and cell lines, which was unfavorable to the prognosis of EC. Knockdown of LINC00958 reduced proliferative, migratory and invasive rates in KLE and Ishikawa cells. MiR-3174 shared a binding site in the 3'-untranslated region (3'-UTR) to that of LINC00958, which was lowly expressed in EC specimens and negatively linked to LINC00958 level. Overexpression of miR-3174 partially abolished the role of LINC00958 in accelerating the malignant phenotypes of EC cells. PHF6 was the downstream target of miR-3174 and it was upregulated in EC specimens. CONCLUSIONS: LINC00958 is upregulated in EC specimens, which is a prognostic factor of EC. It stimulates EC to proliferate, migrate and invade through the miR-3174/PHF6 axis. [ABSTRACT FROM AUTHOR]

Published
2021

49. Upregulation of miR-335 reduces myocardial injury following myocardial infarction via targeting MAP3K2.

Author

WANG, A.-D., DAI, L.-F., YANG, L., WANG, Y.-S., HAO, X.-H., LIU, Z.-C., and CHEN, P.-L.

Abstract

OBJECTIVE: Acute myocardial infarction (AMI) is a serious cardiovascular disease with a high incidence worldwide and the main cause of sudden cardiac death. The aim of this article was to study the protective role of miR-335 in myocardial infarction (MI) and the underlying molecular mechanism. MATERIALS AND METHODS: Thirty Sprague Dawley (SD) rats were randomly divided into sham group, MI + NC group and MI + agomiR-335 group. The expression of miR-335 in rat myocardium was detected by quantitative Real Time-Polymerase Chain Reaction (RTPCR). Western blot was performed to detect the expression of TNF-α, IL-6, IL-1β, Caspase-3, Cleaved Caspase-3 (C-Caspase-3) and MAP3K2 in rat myocardium. On the 7th day of the establishment of the rat MI model, a high-resolution small animal ultrasound system was utilized to detect the cardiac function of the rats, and the heart tissues and blood samples of the rats were collected. The corresponding kits were purchased to detect the contents of LDH, CKMB, MDA and SOD in rat serum, and HE staining was employed to observe the morphology of rat myocardial tissue. RESULTS: The expression of miR-335 in myocardial infarcted zones and border zones of MI rats decreased significantly. The upregulation of miR-335 remarkably inhibited myocardial inflammation and apoptosis after MI, thus improving the cardiac function of MI rats. Compared with the sham group, the MAP3K2 expression in the MI + NC group was observably increased, while the overexpression of miR-335 could inhibit the expression of this protein. Through the Luciferase reporter gene experiment, we found that miR-335 could directly target MAP3K2. CONCLUSIONS: The expression of miR-335 decreased in myocardial tissue after MI, and the overexpression of miR-335 reduced myocardial damage by inhibiting oxidative stress, inflammation, and apoptosis via targeting MAP3K2, thereby improving the cardiac function of MI rats. [ABSTRACT FROM AUTHOR]

Published
2021

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