J/ApJ/878/71 ULXs with multiepoch Spitzer/IRAC obs. (Lau+, 2019) ================================================================================ Uncovering red and dusty ultraluminous X-ray sources with Spitzer. Lau R.M., Heida M., Walton D.J., Kasliwal M.M., Adams S.M., Cody A.M., De K., Gehrz R.D., Furst F., Jencson J.E., Kennea J.A., Masci F. =2019ApJ...878...71L ================================================================================ ADC_Keywords: X-ray sources; Photometry, infrared; Magnitudes, absolute; Galaxies, IR; Surveys; Active gal. nuclei; Stars, giant Keywords: circumstellar matter ; dust, extinction ; infrared: stars; stars: black hole ; stars: neutron ; supergiants Abstract: 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 dM/dt~1x10^-4^M_{sun}_/yr in dust-forming outflows of red ULXs. Based on the transient mid-IR behavior and its relatively flat spectral index, {alpha}=-0.19+/-0.1, we suggest that the mid-IR emission from Holmberg IX X-1 originates from a variable jet. Description: In order to search for mid-IR ultraluminous X-ray (ULX) counterparts, we utilized imaging data taken in the SPitzer InfraRed Intensive Transient Survey (SPIRITS; Kasliwal+ 2017, J/ApJ/839/88) as well as archival Spitzer Post Basic Calibrated (PBCD) imaging data from the Spitzer Heritage Archive. SPIRITS is a program that has been going in since 2014 and has been renewed for Spitzer Cycle 14 (until 2019 November 30). Additionally, many of the nearby ULX host galaxies have previous imaging observations with Spitzer from as long ago as 2004. As part of SPIRITS, we performed follow-up ground-based near-IR J, H, and/or Ks imaging observations with the Multi-object Spectrometer for Infra-red Exploration (MOSFIRE) on Keck I, FourStar on the Magellan 6.5m Baade Telescope, and the Wide Field Infrared Camera (WIRC) on the Palomar 200 inch Telescope. In a dedicated IR ULX follow-up program, the ULX Holmberg II X-1 was observed with the NIRC2 instrument on Keck II with the laser guide star adaptive optics (LGSAO) system on 2018 November 28. See Section 2.4. In order to investigate possible correlations between mid-IR/X-ray variability in ULXs from our Spitzer DDT program (PID-13163), we conducted contemporaneous observations with the X-ray Telescope (XRT) on the Neil Gehrels Swift Observatory of five ULXs: Holmberg II X-1, Holmberg IX X-1, NGC 925 ULX1, NGC 925 ULX2, and NGC 253 ULX1. See Section 2.5. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 154 96 ULX candidate sample table2.dat 100 433 Spitzer/IRAC observations of candidate stellar mid-IR ULX counterparts table4.dat 112 31 Candidate star clusters, AGN, and background galaxy ULX counterparts table5.dat 94 149 Spitzer/IRAC mid-IR non-detections of ULXs -------------------------------------------------------------------------------- See also: B/swift : Swift Master Catalog (HEASARC, 2004-) II/311 : WISE All-Sky Data Release (Cutri+ 2012) IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019) J/A+AS/142/425 : BVRI photometry of 6 galaxies (Drozdovsky+, 2000) J/ApJ/560/675 : Chandra X-ray point sources in Cen A (Kraft+, 2001) J/ApJS/154/519 : Properties of ultraluminous X-ray candidates (Swartz+, 2004) J/ApJ/601/735 : M51 luminous X-ray sources (Terashima+, 2004) J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005) J/A+A/429/1125 : Catalog of Ultraluminous X-ray sources (Liu+, 2005) J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006) J/ApJ/649/730 : ULX population in nearby galaxies from XMM (Winter+, 2006) J/ApJS/173/185 : GALEX UV atlas of nearby galaxies (Gil de Paz+, 2007) J/AJ/138/1003 : IR photometry of massive LMC stars (Bonanos+, 2009) J/ApJ/705/1533 : NGC 5128 globular clusters (Chattopadhyay+, 2009) J/AJ/138/332 : LEDA CMD/tip of the red giant branch (Jacobs+, 2009) J/AJ/140/1475 : ARAUCARIA: NGC 7793 Cepheids (Pietrzynski+, 2010) J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011) J/ApJ/733/124 : Cepheids in M101 observed with HST (Shappee+, 2011) J/ApJ/741/49 : ULX candidates in nearby galaxies (Swartz+, 2011) J/MNRAS/416/1844 : 2XMM ultraluminous X-ray source candidates (Walton+, 2011) J/ApJ/756/27 : Classification of sources from 2XMMi-DR3 (Lin+, 2012) J/MNRAS/419/2095 : HMXBs in nearby galaxies (Mineo+, 2012) J/AJ/146/86 : Cosmicflows-2 catalog (Tully+, 2013) J/MNRAS/446/470 : ULX candidates in luminous IR galaxies (Luangtip+, 2015) J/A+A/587/A121 : The IR source catalog of nearby galaxies (Williams+, 2016) J/ApJS/225/1 : SpIES: the Spitzer IRAC Equatorial Survey (Timlin+, 2016) J/ApJ/836/64 : Luminous variable stars in M31 & M33. IV. (Humphreys+, 2017) J/ApJ/839/88 : 14 unusual IR transients with Spitzer (Kasliwal+, 2017) http://sha.ipac.caltech.edu/applications/Spitzer/SHA/ : Spitzer Heritage Archive Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 11 A11 --- Gal Host galaxy name 13 A1 --- f_Gal [Y/N] Galaxy included in the SPitzer InfraRed Intensive Transient Survey (SPIRITS; Kasliwal+ 2017, J/ApJ/839/88) 15- 43 A29 --- Name ULX name used in this work 45- 74 A30 --- OName Other name 76- 77 I2 h RAh X-ray hour of right ascension (J2000) 79- 80 I2 min RAm X-ray minute of right ascension (J2000) 82- 86 F5.2 s RAs X-ray second of right ascension (J2000) 88 A1 --- DE- X-ray sign of declination (J2000) 89- 90 I2 deg DEd X-ray degree of declination (J2000) 92- 93 I2 arcmin DEm X-ray arcminute of declination (J2000) 95- 98 F4.1 arcsec DEs X-ray arcsecond of declination (J2000) 100-102 F3.1 arcsec ePos [0.3/2.3] 2{sigma} X-ray positional uncertainty 104-108 F5.2 Mpc Dist [1.88/14.19] Adopted distance to the ULX 110-113 F4.2 Mpc e_Dist [0/3.18] Dist uncertainty 115 A1 --- r_Dist Distance reference (1) 117-134 A18 --- Auth Author of the reference for the X-ray position 136-154 A19 --- BibCode Bibcode of the reference for the X-ray position -------------------------------------------------------------------------------- Note (1): The distance references are as follows: A = Gieren et al. (2005ApJ...628..695G) B = Tully et al. (2013AJ....146...86T -- Cosmicflows-2 catalog, J/AJ/146/86) C = Dalcanton et al. (2009ApJS..183...67D) D = Pietrzynski et al. (2010, J/AJ/140/1475) E = McLean et al. (2010SPIE.7735E..1EM) F = Tully et al. (2009AJ....138..323T) G = Jacobs et al. (2009, J/AJ/138/332) H = Karachentsev et al. (2002A&A...383..125K) I = Tully (1988Nearb......221T) J = Shappee & Stanek (2011, J/ApJ/733/124) K = Drozdovsky & Karachentsev (2000, J/A+AS/142/425) L = Poznanski et al. (2009ApJ...694.1067P) M = Tikhonov et al. (2015AstL...41..239T) N = Springob et al. (2009ApJS..182..474S) O = Olivares et al. (2010ApJ...715..833O) P = Willick et al. (1997ApJS..109..333W, VII/198) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 11 A11 --- Gal Host Galaxy 13- 27 A15 --- Name ULX Counterpart name, including host 29- 36 F8.2 d MJD Modified Julian Date (JD-2400000.5) 38- 38 I1 --- IRAC [1/2] IRAC Channel (3.6 or 4.5um) 40- 40 A1 --- l_Flux Limit flag on Flux 42- 47 F6.2 uJy Flux [1.3/277.3] Flux in IRAC channel 49- 52 F4.2 uJy e_Flux [0.2/5.5]? Uncertainty in Flux 54- 54 A1 --- l_mag Limit flag on omag 56- 60 F5.2 mag mag [14.67/20.5] Vega magnitude in IRAC channel 62- 65 F4.2 mag e_mag [0.01/0.3]? Uncertainty in mag 67- 67 A1 --- l_MAG Limit flag on AbsMag 69- 74 F6.2 mag MAG [-13.21/-7.3] Absolute magnitude in IRAC channel 76- 79 F4.2 mag e_MAG [0.01/0.3]? Uncertainty in MAG 81- 84 F4.2 mag ZP [0.03/0.4]? Zeropoint uncertainty error in MAG 86- 94 A9 --- PI Principle Investigator of Observation 96-100 I5 --- PID [60/90240] Program identifier of Observation -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 --- Gal Host Galaxy 12- 40 A29 --- Name ULX Counterpart name, including host 42- 49 F8.2 d MJD Modified Julian Date (JD-2400000.5) 51- 51 I1 --- IRAC [1/2] IRAC Channel 53- 59 F7.2 uJy Flux [40.23/2069.82] Flux in IRAC channel 61- 66 F6.2 uJy e_Flux [0.73/140.18] Uncertainty in Flux 68- 72 F5.2 mag mag [12.44/17.11] Vega magnitude in IRAC channel 74- 78 F5.3 mag e_mag [0.001/0.127] Uncertainty in mag 80- 85 F6.2 mag MAG [-16.9/-12.21] Absolute magnitude in IRAC channel 87- 91 F5.3 mag e_MAG [0.001/0.127] Uncertainty in MAG 93- 96 F4.2 mag ZP [0.03/0.4] Zeropoint uncertainty error in MAG 98-106 A9 --- PI Principle Investigator of Observation 108-112 I5 --- PID [60/80196] Program identifier of Observation -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 A8 --- Gal Host Galaxy 11- 39 A29 --- Name ULX Counterpart name, including host 41 A1 --- n_Name [a] Note on Name (1) 43- 50 F8.2 d MJD Modified Julian Date (JD-2400000.5) 52- 52 I1 --- IRAC [1/2] IRAC Channel 54- 54 A1 --- l_Flux Limit flag on Flux 56- 61 F6.2 uJy Flux [0.82/984.8] Flux in IRAC channel 63- 63 A1 --- l_mag Limit flag on mag 65- 69 F5.2 mag mag [13.0/21.13] Vega magnitude in IRAC channel 71- 71 A1 --- l_MAG Limit flag on MAG 73- 78 F6.2 mag MAG [-16.8/-6.96] Absolute magnitude in IRAC channel 80- 88 A9 --- PI Principle Investigator of Observation 90- 94 I5 --- PID [69/80196] Program identifier of Observation -------------------------------------------------------------------------------- Note (1): [LB2005] NGC 4631 ULX1 and [LB2005] NGC 891 ULX3 are not included in the final ULX sample (Table 1): positional uncertainties greater than 7". -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Dec-2020