Unveiling the X-ray Source Population of the Barred Spiral Galaxy NGC 2336

We present a comprehensive study of the X-ray source population in the nearby spiral galaxy NGC 2336, based on nine Chandra observations spanning a 7-month period. A total of 32 X-ray sources were detected down to a limiting luminosity of ∼ 1.4 × 1038 erg s−1 in the 0.5–7.0 keV (broad) energy band. Five sources exhibit luminosities exceeding 1039 erg s−1 in the broad band in co-added dataset and are classified as ultra-luminous X-ray sources (ULXs). One ULX, with over 90 net counts in a single observation, was analyzed spectrally using an absorbed power-law model, yielding a photon index Γ ∼ 1.8 ± 0.3, consistent with typical ULX spectra. Though this source has been previously classified as a non-active Seyfert 2 nucleus, we refrain from a more detailed classification due to data limitations. Photometric properties were derived for all sources, and hardness ratio analysis revealed six hard sources, including two ULXs. Variability analysis using χ2 statistics identified 13 variable sources over the 7-month period. Eight sources varied in Period 1 (December 2020), and nine in Period 2 (July 2021), while all five ULXs showing long-term variability and two exhibiting mid-term variability. In addition, we identified 2 candidate transient sources: one showing transient behavior in the extended dataset (i.e., both Periods), and in Period 1, and another showing transient behavior only in the extended dataset. To explore possible associations with star- forming regions, we cross-matched the X-ray sources with 78 UV-bright star-forming knots identified from UVIT data. After accounting for chance coincidence via Monte Carlo simulations, nine X-ray sources were confidently associated with UV knots, two of which have hard spectra and are classified as candidate high-mass X-ray binaries (HMXBs). None of the ULXs were reliably associated with UV knots, suggesting a likely low-mass X-ray binary (LMXB) origin. Notably, we identify a candidate transient ULX–LMXB system, a rare class of objects warranting further investigation. Future work will focus on the short-term variability of these sources assessed within each single observation and the analysis of archival HST data to provide detailed optical photometric characterization. This will enable a more complete census of massive star clusters and improved age and metallicity estimates via multi-wavelength stellar population modeling.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Astrophysics

Grantor

Texas Tech University

Year dc:date.issued

2025

Author dc:creator

• Perla, Darien

Chair dc:contributor.committeechair

• Vallia, Antoniou

Committee member dc:contributor.committeemember

• Maccarone, Thomas

• low-mass X-ray binary (LMXB)
• ultra-luminous X-ray sources (ULXs)
• X-ray Astronomy
• NGC 2336 (galaxy)
• high-mass X-ray binaries (HMXBs)
• Stellar evolution

Statement dc:rights

• Restricted from online display. To request the author grant access, click on the PDF link to the left.

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2346/102419

OAI identifier oai:identifier

oai:ttu-ir.tdl.org:2346/102419