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Uncovering Red and Dusty Ultraluminous X-Ray Sources with Spitzer

Lau, Ryan M. and Heida, Marianne and Walton, Dominic J. and Kasliwal, Mansi M. and Adams, Scott M. and Cody, Ann Marie and De, Kishalay and Gehrz, Robert D. and Fürst, Felix and Jencson, Jacob E. and Kennea, Jamie A. and Masci, Frank (2019) Uncovering Red and Dusty Ultraluminous X-Ray Sources with Spitzer. Astrophysical Journal, 878 (1). Art. No. 71. ISSN 1538-4357. doi:10.3847/1538-4357/ab1b1c.

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We present a mid-infrared (IR) sample study of nearby ultraluminous X-ray sources (ULXs) using multiepoch observations with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Spitzer/IRAC observations taken after 2014 were obtained as part of the Spitzer Infrared Intensive Transients Survey. Our sample includes 96 ULXs located within 10 Mpc. Of the 96 ULXs, 12 have candidate counterparts consistent with absolute mid-IR magnitudes of supergiants, and 16 counterparts exceeded the mid-IR brightness of single supergiants and are thus more consistent with star clusters or non-ULX background active galactic nuclei. The supergiant candidate counterparts exhibit a bimodal color distribution in a Spitzer/IRAC color–magnitude diagram, where "red" and "'blue" ULXs fall in IRAC colors [3.6] – [4.5] ~ 0.7 and [3.6] – [4.5] ~ 0.0, respectively. The mid-IR colors and absolute magnitudes of four "red" and five "blue" ULXs are consistent with those of supergiant B[e] (sgB[e]) and red supergiant (RSG) stars, respectively. Although "blue," RSG-like mid-IR ULX counterparts likely host RSG mass donors; we propose that "red" counterparts are ULXs exhibiting the "B[e] phenomenon" rather than hosts of sgB[e] mass donors. We show that the mid-IR excess from the "red" ULXs is likely due to thermal emission from circumstellar or circumbinary dust. Using dust as a probe for total mass, we estimate mass-loss rates of Ṁ ~ 1 x 10^(-4) M_⊙ yr^(−1) in dust-forming outflows of red ULXs. Based on the transient mid-IR behavior and its relatively flat spectral index, α = −0.19 ± 0.1, we suggest that the mid-IR emission from Holmberg IX X-1 originates from a variable jet.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Heida, Marianne0000-0002-1082-7496
Walton, Dominic J.0000-0001-5819-3552
Kasliwal, Mansi M.0000-0002-5619-4938
Adams, Scott M.0000-0001-5855-5939
Cody, Ann Marie0000-0002-3656-6706
De, Kishalay0000-0002-8989-0542
Gehrz, Robert D.0000-0003-1319-4089
Fürst, Felix0000-0003-0388-0560
Jencson, Jacob E.0000-0001-5754-4007
Kennea, Jamie A.0000-0002-6745-4790
Masci, Frank0000-0002-8532-9395
Additional Information:© 2019. The American Astronomical Society. Received 2019 February 8; revised 2019 March 31; accepted 2019 April 8; published 2019 June 14. We thank the anonymous referee for valuable comments and insight that improved the quality of this work. We also acknowledge C. Alvarez, N. Blagorodnova, and the staff of the W. M. Keck Observatory for supporting observations and the assistance with data reduction. We also thank M. Bachetti, B. Binder, H. Bond, Y. Götberg, B. Grefenstette, I. El Mellah, P. Jonker, P. Kosec, E. Levesque, K. Lopez, C. Pinto, P. Podsiadlowski, and R. Soria for the enlightening discussions on ULXs, RSGs, sgB[e]s, and dust. R.M.L. acknowledges the Japan Aerospace Exploration Agency's International Top Young Fellowship. D.J.W. acknowledges financial support from STFC in the form of an Ernest Rutherford fellowship. R.D.G. was supported by NASA and the United States Air Force. J.J. is supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-1144469. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. Some of the data presented herein were obtained at Palomar Observatory, which is operated by a collaboration between California Institute of Technology, Jet Propulsion Laboratory, Yale University, and National Astronomical Observatories of China. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are fortunate to have the opportunity to conduct observations from this mountain. Facility: Spitzer (IRAC), Hale (WIRC), Magellan:Baade (FourStar), Keck:I (MOSFIRE), Keck:II (NIRC2), Swift (XRT).
Group:Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
Japan Aerospace Exploration Agency (JAXA)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:circumstellar matter; dust, extinction; infrared: stars; stars: black hole ; stars: neutron; supergiants
Issue or Number:1
Record Number:CaltechAUTHORS:20190614-091205859
Persistent URL:
Official Citation:Ryan M. Lau et al 2019 ApJ 878 71
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96443
Deposited By: George Porter
Deposited On:14 Jun 2019 22:07
Last Modified:16 Nov 2021 17:21

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