In:
The Astrophysical Journal, American Astronomical Society, Vol. 946, No. 2 ( 2023-04-01), p. 72-
Abstract:
We present a deep optical imaging campaign on the starburst galaxy NGC 4631 with CFHT/MegaCam. By supplementing the HST/ACS and Chandra/ACIS archival data, we search for the optical counterpart candidates of the five brightest X-ray sources in this galaxy, four of which are identified as ultraluminous X-ray sources (ULXs). The stellar environments of the X-ray sources are analyzed using the extinction-corrected color–magnitude diagrams and the isochrone models. We discover a highly asymmetric bubble nebula around X4 that exhibits different morphology in the H α and [O iii ] images. The [O iii ]/H α ratio map shows that the H α -bright bubble may be formed mainly via the shock ionization by the one-sided jet/outflow, while the more compact [O iii ] structure is photoionized by the ULX. We constrain the bubble expansion velocity and interstellar medium density with the MAPPINGS V code and hence estimate the mechanical power injected into the bubble as P w ∼ 5 × 10 40 erg s −1 and the corresponding bubble age as ∼7 × 10 5 yr. Relativistic jets are needed to provide such a level of mechanical power with a mass-loss rate of ∼10 −7 M ⊙ yr −1 . Besides the accretion, the black hole spin is likely an additional energy source for the super-Eddington jet power.
Type of Medium:
Online Resource
ISSN:
0004-637X
,
1538-4357
DOI:
10.3847/1538-4357/acaddd
Language:
Unknown
Publisher:
American Astronomical Society
Publication Date:
2023
detail.hit.zdb_id:
2207648-7
detail.hit.zdb_id:
1473835-1
SSG:
16,12
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