Diffuse X-Ray Emission in the Cygnus OB2 Association
We present a large-scale study of diffuse X-ray emission in the nearby massive stellar association Cygnus OB2 as part of the Chandra Cygnus OB2 Legacy Program. We used 40 Chandra X-ray ACIS-I observations covering ∼1.0 deg ^2 . After removing 7924 point sources detected in our survey and applying ad...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Supplement Series |
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| Online Access: | https://doi.org/10.3847/1538-4365/acdd65 |
| _version_ | 1797649167355478016 |
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| author | J. F. Albacete-Colombo J. J. Drake E. Flaccomio N. J. Wright V. Kashyap M. G. Guarcello K. Briggs J. E. Drew D. M. Fenech G. Micela M. McCollough R. K. Prinja N. Schneider S. Sciortino J. S. Vink |
| author_facet | J. F. Albacete-Colombo J. J. Drake E. Flaccomio N. J. Wright V. Kashyap M. G. Guarcello K. Briggs J. E. Drew D. M. Fenech G. Micela M. McCollough R. K. Prinja N. Schneider S. Sciortino J. S. Vink |
| author_sort | J. F. Albacete-Colombo |
| collection | DOAJ |
| description | We present a large-scale study of diffuse X-ray emission in the nearby massive stellar association Cygnus OB2 as part of the Chandra Cygnus OB2 Legacy Program. We used 40 Chandra X-ray ACIS-I observations covering ∼1.0 deg ^2 . After removing 7924 point sources detected in our survey and applying adaptive smoothing to the background-corrected X-ray emission, the adaptive smoothing reveals large-scale diffuse X-ray emission. Diffuse emission was detected in the subbands soft (0.5−1.2 keV) and medium (1.2−2.5 keV) and marginally in the hard (2.5−7.0 keV) band. From X-ray spectral analysis of stacked spectra we compute a total (0.5–7.0 keV) diffuse X-ray luminosity of ${L}_{{\rm{X}}}^{\mathrm{diff}}\approx $ 4.2 × 10 ^34 erg s ^−1 , characterized by plasma temperature components at kT ≈ 0.11, 0.40, and 1.18 keV, respectively. The H i absorption column density corresponding to these temperatures has a distribution consistent with N _H = (0.43, 0.80, 1.39) × 10 ^22 cm ^−2 . The extended medium-band energy emission likely arises from O-type stellar winds thermalized by wind−wind collisions in the most populated regions of the association, while the soft-band emission probably arises from less energetic termination shocks against the surrounding interstellar medium. Supersoft and soft diffuse emission appears more widely dispersed and intense than the medium-band emission. The diffuse X-ray emission is generally spatially coincident with low-extinction regions that we attribute to the ubiquitous influence of powerful stellar winds from massive stars and their interaction with the local interstellar medium. Diffuse X-ray emission is volume filling, rather than edge brightened, oppositely to other star-forming regions. We reveal the first observational evidence of X-ray halos around some evolved massive stars. |
| first_indexed | 2024-03-11T15:42:21Z |
| format | Article |
| id | doaj.art-9b591d752e11426aba233f62e3ef3500 |
| institution | Directory Open Access Journal |
| issn | 0067-0049 |
| language | English |
| last_indexed | 2024-03-11T15:42:21Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Supplement Series |
| spelling | doaj.art-9b591d752e11426aba233f62e3ef35002023-10-26T11:56:10ZengIOP PublishingThe Astrophysical Journal Supplement Series0067-00492023-01-0126911410.3847/1538-4365/acdd65Diffuse X-Ray Emission in the Cygnus OB2 AssociationJ. F. Albacete-Colombo0https://orcid.org/0000-0001-8398-0515J. J. Drake1https://orcid.org/0000-0002-0210-2276E. Flaccomio2https://orcid.org/0000-0002-3638-5788N. J. Wright3V. Kashyap4https://orcid.org/0000-0002-3869-7996M. G. Guarcello5https://orcid.org/0000-0002-3010-2310K. Briggs6J. E. Drew7D. M. Fenech8G. Micela9https://orcid.org/0000-0002-9900-4751M. McCollough10https://orcid.org/0000-0002-8384-3374R. K. Prinja11N. Schneider12https://orcid.org/0000-0001-6720-5519S. Sciortino13J. S. Vink14Universidad de Río Negro , Sede Atlántica, Viedma CP8500, Argentina ; albacete.facundo@conicet.gov.arSmithsonian Astrophysical Observatory , 60 Garden St., Cambridge, MA 02138, USAINAF-Osservatorio Astronomico di Palermo , Piazza del Parlamento 1, I-90134 Palermo, ItalyAstrophysics Group, Keele University , Keele, Staffordshire ST5 5BG, UKSmithsonian Astrophysical Observatory , 60 Garden St., Cambridge, MA 02138, USAINAF-Osservatorio Astronomico di Palermo , Piazza del Parlamento 1, I-90134 Palermo, ItalyHamburger Sternwarte, University of Hamburg , Gojenbergsweg 112, D-21029, Hamburg, GermanySchool of Physics, Astronomy & Mathematics, University of Hertfordshire , College Lane, Hatfield, Hertfordshire AL10 9AB, UKDepartment of Physics and Astronomy, University College London , Gower Street, London WC1E 6BT, UKINAF-Osservatorio Astronomico di Palermo , Piazza del Parlamento 1, I-90134 Palermo, ItalySmithsonian Astrophysical Observatory , 60 Garden St., Cambridge, MA 02138, USADepartment of Physics and Astronomy, University College London , Gower Street, London WC1E 6BT, UKI. Physik. Institut, University of Cologne , D-50937 Cologne, GermanyINAF-Osservatorio Astronomico di Palermo , Piazza del Parlamento 1, I-90134 Palermo, ItalyArmagh Observatory and Planetarium , College Hill, Armagh BT61 9DG, UKWe present a large-scale study of diffuse X-ray emission in the nearby massive stellar association Cygnus OB2 as part of the Chandra Cygnus OB2 Legacy Program. We used 40 Chandra X-ray ACIS-I observations covering ∼1.0 deg ^2 . After removing 7924 point sources detected in our survey and applying adaptive smoothing to the background-corrected X-ray emission, the adaptive smoothing reveals large-scale diffuse X-ray emission. Diffuse emission was detected in the subbands soft (0.5−1.2 keV) and medium (1.2−2.5 keV) and marginally in the hard (2.5−7.0 keV) band. From X-ray spectral analysis of stacked spectra we compute a total (0.5–7.0 keV) diffuse X-ray luminosity of ${L}_{{\rm{X}}}^{\mathrm{diff}}\approx $ 4.2 × 10 ^34 erg s ^−1 , characterized by plasma temperature components at kT ≈ 0.11, 0.40, and 1.18 keV, respectively. The H i absorption column density corresponding to these temperatures has a distribution consistent with N _H = (0.43, 0.80, 1.39) × 10 ^22 cm ^−2 . The extended medium-band energy emission likely arises from O-type stellar winds thermalized by wind−wind collisions in the most populated regions of the association, while the soft-band emission probably arises from less energetic termination shocks against the surrounding interstellar medium. Supersoft and soft diffuse emission appears more widely dispersed and intense than the medium-band emission. The diffuse X-ray emission is generally spatially coincident with low-extinction regions that we attribute to the ubiquitous influence of powerful stellar winds from massive stars and their interaction with the local interstellar medium. Diffuse X-ray emission is volume filling, rather than edge brightened, oppositely to other star-forming regions. We reveal the first observational evidence of X-ray halos around some evolved massive stars.https://doi.org/10.3847/1538-4365/acdd65X-ray starsMassive starsStellar winds |
| spellingShingle | J. F. Albacete-Colombo J. J. Drake E. Flaccomio N. J. Wright V. Kashyap M. G. Guarcello K. Briggs J. E. Drew D. M. Fenech G. Micela M. McCollough R. K. Prinja N. Schneider S. Sciortino J. S. Vink Diffuse X-Ray Emission in the Cygnus OB2 Association The Astrophysical Journal Supplement Series X-ray stars Massive stars Stellar winds |
| title | Diffuse X-Ray Emission in the Cygnus OB2 Association |
| title_full | Diffuse X-Ray Emission in the Cygnus OB2 Association |
| title_fullStr | Diffuse X-Ray Emission in the Cygnus OB2 Association |
| title_full_unstemmed | Diffuse X-Ray Emission in the Cygnus OB2 Association |
| title_short | Diffuse X-Ray Emission in the Cygnus OB2 Association |
| title_sort | diffuse x ray emission in the cygnus ob2 association |
| topic | X-ray stars Massive stars Stellar winds |
| url | https://doi.org/10.3847/1538-4365/acdd65 |
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