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M 31 Central Field Chandra HRI X-Ray Point Source Catalog

Metadata Updated: September 19, 2025

The central field of the Andromeda galaxy (M 31) was monitored from 2006 to 2012 using the Chandra HRC-I detector (about 0.1 - 10 keV energy range) with the main aim of detecting X-rays from optical novae. The authors present a systematic analysis of all X-ray sources found in the 41 nova monitoring observations, along with 23 M 31 central field HRC-I observations available from the Chandra data archive starting in December 1999. Based on these observations, they studied the X-ray long-term variability of the source population and especially of the X-ray binaries in M31. The authors created a catalog of sources detected in the 64 available observations that adds up to a total exposure time of about 1 Ms. To study the variability, they developed a processing pipeline to derive long-term Chandra HRC-I light curves for each source over the 13 years of observations, and also searched for extended X-ray sources in the merged images. This table contains the point-source catalog of 318 X-ray sources with detailed long-term variability information, 28 of which are published for the first time. The spatial and temporal resolution of the catalog allows the authors to classify 115 X-ray binary candidates showing high X-ray variability or even outbursts, as well as 14 globular cluster X-ray binary candidates showing no significant variability. The analysis may suggest that outburst sources are less frequent in globular clusters than in the field of M 31. Seven supernova remnants (not included in the point-source catalog) were detected, one of which is a new candidate, and also the first X-rays from a known radio supernova remnant were resolved. In addition to 33 known optical nova/X-ray source correlations, the authors discovered one previously unknown super-soft X-ray outburst and several new nova candidates. A large sample of detailed long-term X-ray light curves of sources in the M31 central field has been obtained in this study (see Appendix B.1 of the reference paper), which helps in understanding the X-ray population of our neighboring spiral galaxy M 31. Based on all the available Chandra HRC-I observations (see Table A.1 in the reference paper for the complete list), a source catalog has been created (available in this HEASARC table) and the energy flux of each source in every individual observation derived (these are not available in this HEASARC table, but are obtainable at the CDS: for more details, see the files <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A%2BA/555/A65/ReadMe">https://cdsarc.cds.unistra.fr/ftp/cats/J/A%2BA/555/A65/ReadMe</a>; and <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J_A%2BA/555/A65/table2.dat.gz">https://cdsarc.cds.unistra.fr/ftp/cats/J_A%2BA/555/A65/table2.dat.gz</a>;). One thing to be aware of is that, in the latter file, upper limits are denoted by a '>' symbol rather than the more usual '<' symbol!). These fluxes were calculated assuming a generic power law spectrum and Galactic foreground absorption for each source. This table was created by the HEASARC in August 2013 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/555/A65">CDS catalog J/A+A/555/A65</a> files table1.dat and xcorr.dat. This is a service provided by NASA HEASARC .

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Created Date April 11, 2025
Metadata Updated Date September 19, 2025

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date September 19, 2025
Publisher High Energy Astrophysics Science Archive Research Center
Maintainer
Identifier ivo://nasa.heasarc/m31cfcxo
Data Last Modified 2025-09-10
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id dddb5121-4917-45ad-be06-daff7e59707a
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL https://heasarc.gsfc.nasa.gov/W3Browse/all/m31cfcxo.html
Program Code 026:000
Source Datajson Identifier True
Source Hash 64e63d4953b0a02b5727ca60c3ca68d9d716350b80955b804d83730ca0836329
Source Schema Version 1.1

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