THE FIRST DETECTION OF [O IV] FROM AN ULTRALUMINOUS X-RAY SOURCE WITH SPITZER. II. EVIDENCE FOR HIGH LUMINOSITY IN HOLMBERG II ULX

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/708/1/364· OSTI ID:21392466

Berghea, C T ^[1]; Dudik, R P ^[2]; Weaver, K A

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1. Physics Department, Catholic University of America, Washington, DC 20064 (United States)
2. United States Naval Observatory, Washington, DC 20392 (United States)

This is the second of two papers examining Spitzer Infrared Spectrograph observations of the ultraluminous X-ray source (ULX) in Holmberg II. Here, we perform detailed photoionization modeling of the infrared lines. Our analysis suggests that the luminosity and morphology of the [O IV] 25.89 mum emission line is consistent with photoionization by the soft X-ray and far ultraviolet (FUV) radiation from the accretion disk of the binary system and inconsistent with narrow beaming. We show that the emission nebula is matter-bounded both in the line-of-sight direction and to the east, and probably radiation-bounded to the west. A bolometric luminosity in excess of 10{sup 40} erg s{sup -1} would be needed to produce the measured [O IV] flux. We use modeling and previously published studies to conclude that shocks likely contribute very little, if at all, to the high-ionization line fluxes observed in the Holmberg II ULX. Additionally, we find that the spectral type of the companion star has a surprisingly strong effect on the predicted strength of the [O IV] emission. This finding could explain the origin of [O IV] in some starburst systems containing black hole binaries.

• OSTI ID: 21392466
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 708; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BLACK HOLES
BOLOMETERS
ELECTROMAGNETIC RADIATION
EMISSION
FAR ULTRAVIOLET RADIATION
GALAXIES
IONIZATION
IONIZING RADIATIONS
LUMINOSITY
MATTER
MEASURING INSTRUMENTS
MORPHOLOGY
NEBULAE
OPTICAL PROPERTIES
PHOTOIONIZATION
PHYSICAL PROPERTIES
RADIATION SOURCES
RADIATIONS
SIMULATION
SOFT X RADIATION
STARS
ULTRAVIOLET RADIATION
X RADIATION
X-RAY SOURCES