arXiv subjects

Maria Rah

Publications and source records attributed to Maria Rah.

5 recordsLinked to original sources

arXiv2026

Pulsars and Millisecond Pulsars I: Advancements, Open Questions and finding Gaps via statistical insights

We present a statistical study of pulsars and millisecond pulsars (MSPs) based on multiwavelength observations in the Galactic Field and Globular Clusters. We examine their emission properties, timing behavior, and spatial distributions, and discuss how theoretical models are required to interpret these observational trends. We focus on the magnetic field spin relation, including spin up through accretion in binaries and spin down driven by magnetic dipole radiation. Using numerical tools such as NBODY6++GPU, CMC, and COMPASS, we explore how dynamical interactions and binary evolution shape the properties of compact objects. Despite major progress, several open questions remain regarding binary interactions, magnetic field evolution, and the incorporation of pulsar physics into large scale simulations. Our analysis highlights the need for improved modeling frameworks to better understand the formation pathways and long term evolution of pulsars and MSPs.

astro-ph.HE↗

arXiv2026

Pulsars and Millisecond Pulsars II: Deep diving into the Evolutionary Mechanisms

This second paper in our series investigates the evolutionary mechanisms that shape pulsars and millisecond pulsars (MSPs) across different astrophysical environments. We focus on the physical processes that govern spin evolution, magnetic field decay, binary interactions, and recycling pathways. Using observational constraints together with theoretical models, we examine how accretion, magnetic braking, and dynamical encounters contribute to the long-term evolution of compact objects. We also explore how these mechanisms differ between the Galactic Field and Globular Clusters, where stellar densities and interaction rates vary significantly. By integrating insights from population studies and numerical tools such as NBODY6++GPU, CMC, and COMPASS, we aim to clarify the dominant channels that lead to the formation and transformation of pulsars and MSPs. Our results highlight key uncertainties in current models and outline the physical ingredients required for more accurate simulations of compact object evolution.

astro-ph.HE↗

arXiv2024

Unraveling the Origins and Development of the Galactic Disk through Metal-Poor Stars

The Milky Way is a spiral galaxy comprising three main components: the Bulge, the Disk, and the Halo. Of particular interest is the Galactic disk, which holds a significant portion of the baryonic matter angular momentum and harbors at least two primary stellar populations: the thin and thick disks. Understanding the formation and evolution of the Galactic disk is crucial for comprehending the origins and development of our Galaxy. Stellar archaeology offers a means to probe the disk's evolution by listening to the cosmological narratives of its oldest and most pristine stars, specifically the metal-poor stars. In this study, we employed accurate photometric metallicity estimates and Gaia Early Data Release 3 astrometry to curate a pure sample of the oldest Galactic stars. This proceeding presents a summary of our primary findings.

astro-ph.GA↗

arXiv2021

Metal-poor Stars Observed with the Automated Planet Finder Telescope. III. CEMP-no Stars are the Descendant of Population III Stars

In this study, we report a probabilistic insight into the stellar mass and supernovae (SNe) explosion energy of the possible progenitors of five CEMP-no stars. This was done by a direct comparison between the abundance ratios [X/Fe] of the light-elements and the predicted nucleosynthetic yields of SN of high-mass metal-free stars. This comparison suggests possible progenitors with stellar mass range of 11 - 22\,M$_{\odot}$ and explosion energies of $0.3 - 1.8 \times 10^{51}$\,erg. The coupling of the chemical abundances with kinematics derived from $Gaia$ DR2 suggests that our sample do not enter the outer-halo region. In addition, we suggest that these CEMP-no stars are not $Gaia$-Sausage nor $Gaia$-Sequoia remnant stars, but another accretion event might be responsible for the contribution of these stars to the Galactic Halo of the Milky-Way.

astro-ph.GA↗

arXiv2020

Simulation of the orbit and spin period evolution of the double pulsars PSR J0737-3039 from their birth to coalescence induced by the gravitational wave radiation

The complete orbital and sin period evolutions of the double neutron star (NS) system PSR J0737-3039 are simulated from the birth to coalescence, which include the two observed radio pulsars classified as primary NS PSR J0737-3039A and companion NS PSR J0737-3039B. By employing the characteristic age of PSR J0737-3039B to constrain the true age of the double pulsar system, the initial orbital period and initial binary separation are obtained as 2.89 hrs and $1.44 \times 10^{6}$ km, respectively, and the coalescence age or the lifetime from the birth to merger of PSR J0737-3039 is obtained to be $1.38 \times 10^{8}$ yr. At the last minute of coalescence, corresponding to that the gravitational wave frequency changes from 20 Hz to 1180 Hz, we present the binary separation of PSR J0737-3039 to be from 442 km to 30 km, while the spin periods of PSR J0737-3039A and PSR J0737-3039B are 27.10 ms and 4.63 s, respectively. From the standard radio pulsar emission model, before the system merged, the primary NS could still be observed by the radio telescope, while the companion NS has crossed the death line in the pulsar magnetic-field versus period ($B-P$) diagram which is usually considered to cease the life as a pulsar. It is for the first time that the whole life evolutionary simulation of the orbit and spin periods for double NS system is presented, which provides the useful information for observing the primary NS at the coalescence stage.

astro-ph.HE↗