Abstract Details

Name: Shaswata Chowdhury
Affiliation: The Institute of Mathematical Sciences
Conference ID: ASI2026_16
Title: CME Signature and Mode Change in InPTA Millisecond Pulsars
Abstract Type: Oral
Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy
Author(s) and Co-Author(s) with Affiliation: Shaswata Chowdhury(The Institute of Mathematical Sciences, Chennai, India.), M. A. Krishnakumar(Radio Astronomy Centre, National Centre for Radio Astrophysics, Tata Institute of Fundamental Physics, Udhagamandalam, TamilNadu), Manjari Bagchi(1) The Institute of Mathematical Sciences, Chennai; 2) Homi Bhabha National Institute, Mumbai), Bhal Chandra Joshi(1) National Centre for Radio Astrophysics, Pune; 2) Department of Physics, Indian Institute of Technology Roorkee, Roorkee), Nobleson K.(Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan), Jibin Jose(Department of Astronomy, Astrophysics, and Space Engineering, Indian Institute of Technology Indore, Indore 453552, India), Shantanu Desai(Department of Physics IIT Hyderabad. Kandi, Telangana 502284), Manpreet Singh(Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, SAS Nagar, Mohali), Vaishnavi Vyasraj(Department of Physics, IIT Hyderabad, Kandi, Telangana - 502284), Kuldeep Meena(UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Vidyanagari, Mumbai 400098, India.), Amarnath(Raman Research Institute, Bengaluru 560080, Karnataka, India), Manoneeta Chakraborty(Department of Astronomy, Astrophysics and Space Engineering, Indian Institute of Technology Indore, Indore 453552, India), Shubham Kala(The Institute of Mathematical Sciences, C. I. T. Campus, Taramani, Chennai 600113, India), Debabrata Deb(Centre for Space Research, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa), Zenia Zuraiq(Department of Physics, Indian Institute of Science, C. V. Raman Avenue, Bengaluru 560012, India), Arul Pandian B(1) Raman Research Institute, Bengaluru; 2) Department of Physics and Electronics, The Christ, Bangalore), Neelam Dhanda Batra(Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016), Churchil Dwivedi(Astronomy and Astrophysics Division, Physical Research Laboratory, Thaltej Campus, Ahmedabad 380059, Gujarat, India), Sushovan Mondal(1) The Institute of Mathematical Sciences, Chennai; 2) Homi Bhabha National Institute, Mumbai), Avinash Kumar Paladi(Joint Astronomy Programme (JAP), Department of Physics, Indian Institute of Science, C. V. Raman Avenue, Bengaluru 560012, India), Kaustubh rai(Department of Physics, IISER Bhopal, Bhauri Bypass Road, Bhopal, 462066, India), Abhimanyu Susobhanan(Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Callinstra{\ss}e 38, D-30167 Hannover, Germany), Adya Shukla(Department of Physics, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India), Aman Srivastava(1) Department of Physics, GLA University, Mathura; 2)Department of Physics IIT Hyderabad. Kandi, Telangana), Mayuresh Surnis(Department of Physics, IISER Bhopal, Bhauri Bypass Road, Bhopal, 462066, India), Hemanga Tahbildar(Department of Physics, IISER Bhopal, Bhauri Bypass Road, Bhopal, 462066, India), Keitaro Takahashi(Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan), Pratik Tarafdar(INAF - Osservatorio Astronomico di Cagliari, via della Scienza 5, 09047 Selargius (CA), Italy), Prabu T(Raman Research Institute, Bengaluru 560080, Karnataka, India), Kunjal Vara(Department of Physics, IISER Bhopal, Bhauri Bypass Road, Bhopal, 462066, India)
Abstract: The second data release of the Indian Pulsar Timing Array (InPTA-DR2) comprises seven years of high-precision timing observations of 27 millisecond pulsars, obtained simultaneously at low (band 3: 300-500 MHz) and high (band 5: 1260-1460 MHz) radio frequencies using the upgraded Giant Metrewave Radio Telescope (uGMRT). The low-frequency data are especially sensitive to dispersion-measure (DM) fluctuations, making them powerful probes for identifying any intrinsic changes in a pulsar or changes in the medium of propagation of the radio signal. In this talk, I will focus on two striking DM outliers identified in the low frequency band-3 data of PSR J1022+1001 and PSR J2145−0750. PSR J1022+1001 lies extremely close to the ecliptic plane, while PSR J2145−0750 is one of the brightest millisecond pulsars and exhibits a multi-component pulse profile. We show that the DM excursion observed in PSR J1022+1001 is consistent with a coronal mass ejection intersecting the pulsar line of sight, whereas the anomalous DM behavior in PSR J2145−0750 is best explained by a possible intrinsic mode-changing event. By directly contrasting these two cases, I demonstrate how solar-event–driven and intrinsic pulsar-origin DM variations produce distinct observational signatures. This provides a physically motivated framework for classifying scientific outliers in PTA datasets and improves DM modelling essential for high-precision pulsar timing and PTA science.