Pulsars, transients and relativistic astrophysics

Research group

Research theme

Sub department

About

Radio pulse profile evolution of magnetar Swift J1818.0−1607

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 528:2 (2024) 3833-3843

Authors:

R Fisher, EM Butterworth, KM Rajwade, BW Stappers, G Desvignes, R Karuppusamy, M Kramer, K Liu, AG Lyne, MB Mickaliger, B Shaw, P Weltevrede

The fast transient AT 2023clx in the nearby LINER galaxy NGC 3799 as a tidal disruption of a very low-mass star

(2024)

Authors:

P Charalampopoulos, R Kotak, T Wevers, G Leloudas, T Kravtsov, M Pursiainen, P Ramsden, TM Reynolds, A Aamer, JP Anderson, I Arcavi, Y-Z Cai, T-W Chen, M Dennefeld, L Galbany, M Gromadzki, CP Guti'errez, N Ihanec, T Kangas, E Kankare, E Kool, A Lawrence, P Lundqvist, L Makrygianni, S Mattila, TE Müller-Bravo, M Nicholl, F Onori, A Sahu, SJ Smartt, J Sollerman, Y Wang, DR Young

Optical spectroscopy of blazars for the Cherenkov Telescope Array -- III

(2024)

Authors:

F D'Ammando, P Goldoni, W Max-Moerbeck, J Becerra Gonzalez, E Kasai, DA Williams, N Alvarez-Crespo, M Backes, U Barres de Almeida, C Boisson, G Cotter, V Fallah Ramazani, O Hervet, E Lindfors, D Mukhi-Nilo, S Pita, M Splettstoesser, B van Soelen

A 12.4-day periodicity in a close binary system after a supernova

Nature Springer Nature 625:7994 (2024) 253-258

Authors:

Ping Chen, Avishay Gal-Yam, Jesper Sollerman, Steve Schulze, Richard S Post, Chang Liu, Eran O Ofek, Kaustav K Das, Christoffer Fremling, Assaf Horesh, Boaz Katz, Doron Kushnir, Mansi M Kasliwal, Shri R Kulkarni, Dezi Liu, Xiangkun Liu, Adam A Miller, Kovi Rose, Eli Waxman, Sheng Yang, Yuhan Yao, Barak Zackay, Eric C Bellm, Richard Dekany, Andrew J Drake, Yuan Fang, Johan PU Fynbo, Steven L Groom, George Helou, Ido Irani, Theophile Jegou du Laz, Xiaowei Liu, Paolo A Mazzali, James D Neill, Yu-Jing Qin, Reed L Riddle, Amir Sharon, Nora L Strotjohann, Avery Wold, Lin Yan

Abstract:

Neutron stars and stellar-mass black holes are the remnants of massive star explosions1. Most massive stars reside in close binary systems2, and the interplay between the companion star and the newly formed compact object has been theoretically explored3, but signatures for binarity or evidence for the formation of a compact object during a supernova explosion are still lacking. Here we report a stripped-envelope supernova, SN 2022jli, which shows 12.4-day periodic undulations during the declining light curve. Narrow Hα emission is detected in late-time spectra with concordant periodic velocity shifts, probably arising from hydrogen gas stripped from a companion and accreted onto the compact remnant. A new Fermi-LAT γ-ray source is temporally and positionally consistent with SN 2022jli. The observed properties of SN 2022jli, including periodic undulations in the optical light curve, coherent Hα emission shifting and evidence for association with a γ-ray source, point to the explosion of a massive star in a binary system leaving behind a bound compact remnant. Mass accretion from the companion star onto the compact object powers the light curve of the supernova and generates the γ-ray emission.

X-Ray Polarized View of the Accretion Geometry in the X-Ray Binary Circinus X-1

The Astrophysical Journal Letters American Astronomical Society 961:1 (2024) L8-L8

Authors:

John Rankin, Fabio La Monaca, Alessandro Di Marco, Juri Poutanen, Anna Bobrikova, Vadim Kravtsov, Fabio Muleri, Maura Pilia, Alexandra Veledina, Rob Fender, Philip Kaaret, Dawoon E Kim, Andrea Marinucci, Herman L Marshall, Alessandro Papitto, Allyn F Tennant, Sergey S Tsygankov, Martin C Weisskopf, Kinwah Wu, Silvia Zane, Filippo Ambrosino, Ruben Farinelli, Andrea Gnarini, Iván Agudo, Lucio A Antonelli

Abstract:

Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric ∼16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6% ± 0.3% and 1.4% ± 0.3% at polarization angles of 37° ± 5° and −12° ± 7°, respectively. Thus, we observed a rotation of the polarization angle by 49° ± 8° along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67° ± 11° between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star’s angular momentum with respect to the orbital one