A Multiwavelength Study of X-ray Binaries in M31 with Hubble, Chandra and NuSTAR Margaret Lazzarini1, Ann Hornschemeier2, Benjamin Williams1 , Dan Wik2, Mihoko Yukita2, Neven Vulic2 [email protected] 1University of Washington, 2NASA Goddard Space Flight Center code 662 M31: Powerful Datasets at X-ray and Optical NuSTAR Hard X-ray: 4-25 keV X-ray Binary Compact object (X-ray) + Chandra X-ray: 0.35-8 keV Companion (optical)

ESA Hubble UV-optical-IR

3”

5”

Figure 3: Hubble of area surrounding hard X-ray source from the Figure 2: Chandra image of area surrounding hard X-ray source observed with NuSTAR. RGB Panchromatic Hubble Andromeda Treasury (PHAT). RGB image created Figure 1: Background image of M31 from NASA’s Evolution Explorer (GALEX). Inset shows NuSTAR X-ray image by Wik (2017) in prep. RGB image created with soft Chandra 0.35-1.0 keV energy band as , medium 1.0-2.0 keV energy using Hubble 11600 nm (near IR) filter as red, 8140 Å filter as (I- NuSTAR image created with soft 4.0-6.0 keV NuSTAR band in red, medium 6.0-12.0 keV band in green and hard 12.0-25.0 keV band in . band as green and hard 2.0-8.0 keV energy band as blue. 5” segment for scale. band), 4750 Å filter as blue (g-band). 3” segment included for scale. Optical Counterparts Source Classification with NuSTAR

Pulsar Hard state Figures 4-7: Classification with X- ray Colors: UV images: •red = 3375 Å Hubble near UV filter, •Classification categories: blue=2750 Å Hubble UV filter pulsar. hard/intermediate/soft Optical images: state black hole, ultra Magnitude Magnitude

Magnitude luminous X-ray source (ULX),

Magnitude •red = 11600 nm Hubble near IR filter, Å Å Å Å non-magnetized neutron star

3375 3375 green=8140 Å Hubble I-band filter, 4750 4750 blue=4750 Å Hubble g-band filter •H, M, S are the hard, medium, Key: and soft NuSTAR energy bands 2750 Å - 3375 Å color 3375 Å - 4750 Å color 2750 Å - 3375 Å color 3375 Å - 4750 Å color •White circles represent 1 and 3 sigma (4-6, 6-12, and 12-25 keV, errors on Chandra X-ray source positions. respectively) •Black points on plot show all within •NuSTAR sources with too few 5” of X-ray source. counts were not classified • star shows counterpart in CMD and Figure 8: Color-Color diagram by Wik at al. (2017) in preparation. UV Optical UV Optical cyan circle indicates counterpart in Figure 4 Figure 5 optical image Conclusions & Future Work Non-magnetized neutron star No Classification, Background Galaxy Analyzing Optical Counterparts •Spectral types for clear optical Conclusions counterparts can be determined using the Bayesian Extinction and Stellar Tool 1. Of 36 total sources that were cross matched between the NuSTAR and (BEAST) fits by Gordon et al. (2016) Chandra observations, 8 X-ray sources have clear stellar optical

Magnitude Magnitude counterparts, 7 appear to be associated with globular clusters, and 5 are Magnitude Magnitude Å Å •For sources without clear optical Å Å background . 3375 4750

3375 counterparts, we can analyze 4750 surrounding histories 2. Identification of optical counterparts to X-ray sources provides powerful

2750 Å - 3375 Å color 3375 Å - 4750 Å color into the formation and evolution of X-ray binaries by allowing us to 2750 Å - 3375 Å color 3375 Å - 4750 Å color •X-ray sources that are identified as background galaxies will not have good see and study both objects in the system. stellar matches in the PHAT catalog •Two NuSTAR classified hard-state black Future Work holes have been identified in stellar •Complete spectral fitting of optical counterparts for all sources in NuSTAR-Chandra-PHAT clusters sample with clear optical counterparts. UV Optical UV Optical •For sources without clear optical counterparts (expected for LMXBs) determine star formation Figure 6 Figure 7 history of surrounding stellar population to constrain counterpart age/spectral type.

References: Background Image: Acknowledgements: Wik, D. et al. (2017) in prep. Gordon, K. D. et al. (2016), Apj, 826, 104 Panchromatic Hubble Andromeda Treasury (PHAT) mosaic image. NASA/ Williams, B. F. et al. (2014), ApJ, 215, 9 This work was supported by funding from the Hubble Space Stiele, H. et al. (2011), A&A, 534, A55 HST Williams, B. F. et al. (2017) in prep. Telescope and the Chandra X-ray Observatory. Vulic, N. et al. (2016), MNRAS, 461, 3443