10_1093_mnras_stu1441.pdf (1.38 MB)
Linking the X-ray and infrared properties of star-forming galaxies at z < 1.5
journal contribution
posted on 2023-06-08, 20:48 authored by M Symeonidis, A Georgakakis, M J Page, J Bock, M Bonzini, V Buat, D Farrah, A Franceschini, E Ibar, D Lutz, B Magnelli, G Magdis, Seb OliverSeb Oliver, M Pannella, M Paolillo, D Rosario, I G Roseboom, M Vaccari, C VillforthWe present the most complete study to date of the X-ray emission from star formation in high-redshift (median z = 0.7; z < 1.5), IR-luminous (L IR = 10 10 –10 13 L ? ) galaxies detected by Herschel’s PACS and SPIRE instruments. For our purpose, we take advantage of the deepest X-ray data to date, the Chandra Deep Fields (North and South). Sources which host AGN are removed from our analysis by means of multiple AGN indicators. We find an AGN fraction of 18 ± 2 per cent amongst our sample and note that AGN entirely dominate at values of log [L X /L IR ] > -3 in both hard and soft X-ray bands. From the sources which are star formation dominated, only a small fraction are individually X-ray detected and for the bulk of the sample we calculate average X-ray luminosities through stacking. We find an average soft X-ray to infrared ratio of log ?L SX /L IR ? = -4.3 and an average hard X-ray to infrared ratio of log?L HX /L IR ?=-3.8.WereportthattheX-ray/IRcorrelationisapproximatelylinearthrough the entire range of L IR and z probed and, although broadly consistent with the local (z < 0.1) one, it does display some discrepancies. We suggest that these discrepancies are unlikely to be physical, i.e. due to an intrinsic change in the X-ray properties of star-forming galaxies with cosmic time, as there is no significant evidence for evolution of the L X /L IR ratio with redshift. Instead, they are possibly due to selection effects and remaining AGN contamination. We also examine whether dust obscuration in the galaxy plays a role in attenuating X-rays from star formation, by investigating changes in the L X /L IR ratio as a function of the average dust temperature. We conclude that X-rays do not suffer any measurable attenuation in the host galaxy.
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Publication status
- Published
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- Published version
Journal
Monthly Notices of the Royal Astronomical SocietyISSN
0035-8711Publisher
Oxford University PressExternal DOI
Issue
4Volume
443Page range
3728-3740Department affiliated with
- Physics and Astronomy Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2015-05-15First Open Access (FOA) Date
2015-05-15First Compliant Deposit (FCD) Date
2015-05-15Usage metrics
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