I study accreting supermassive black holes to measure how their activity is linked to their environment.

The main questions my work focuses on are:

  1. How and where do supermassive black holes grow and evolve?

  2. Is there significant interplay between their activity and their environments?

  3. How can the rate of AGN pairs inform us of the expected gravitational wave signal?

I aim to answer these by studying AGN pairs, which are systems of interacting supermassive black holes. Read more about my research below!

Finding the missing population of AGN pairs with BAYMAX

Although major galaxy mergers have been predicted to trigger AGN activity, the sample size of known dual AGN systems remains small. One of the most robust methods of determining the presence of dual AGN is to directly detect them using X-ray observations. However, for dual AGN systems with separations close to the half-energy width of the PSF, a statistical approach is needed to reliably identify dual AGN. I've developed a code BAYMAX (Bayesian AnalYsis of Multiple AGN in X-rays), that allows for a statistical analysis on Chandra observations. I'm using BAYMAX to find AGN pairs that may otherwise be missed, and then using follow-up multi-wavelength coverage (such as HST, SDSS, WISE) to learn more about their environments.

Can you tell a dual AGN from a single AGN?

Chandra simulations of single and dual AGN. By eye, it's impossible to tell the dual AGN from the single AGN.

BAYMAX is able to discern between single and dual AGN for both low flux-ratios (f, as low as ~10 counts from the secondary), and separations (r) <0.5”!

For more information on work analyzing AGN pairs, check out my AGN Pairs page

Or, check out my publications on multiple AGN systems:

Yu-Ching, C., Liu, X., Foord, A., et al., 2022, submitted

Foord, A., Liu, X., Gültekin, K., Whitley, K., Shi, F., C. Y.C. 2021, ApJ, 927, 1

Foord, A., Gültekin, K., Runnoe, J. Koss, M., 2020, ApJ, ApJ, 907, 72

Foord, A., Gültekin, K., Runnoe, J. Koss, M., 2020, ApJ, ApJ, 907, 71

Foord, A., Gültekin, K., Nevin, R., Comerford, J., Hodges-Kluck, E., Barrows, R., Goulding, A., Greene, J. 2020, ApJ, 892, 29

Koss, M., U, V., Hodges-Kluck, E., [et. al, including Foord, A.], 2019

Foord, A., Gültekin, K., Reynolds, M., Hodges-Kluck, E., Cackett, E., Comerford, J., King, A., Miller, J., Runnoe, J. 2019, ApJ, 877, 1

Foord, A., Gültekin, K., Reynolds, M., Ayer, M., Liu, T., Gezari, S., Runnoe, J. 2017, ApJ, 851, 106

For more information on my work analyzing other types of AGN, check out my Other AGN page

Or, check out my publications on other AGN systems:

Pacucci, F., Foord, A., Gordon, L., Loeb, A., 2022, MNRAS, 514, 2

Baldassare, V., Stone, N., Foord, A., Gallo, E., Ostriker, J., ApJ, 929, 84

Napier, K., Foord, A., Gallo, E., Ghisellini, G., Hodges-Kluck, E., Wu, J., Haart, F., Ciardi, B., 2020, MNRAS, accepted

Rakshit, S., Woo, J., Gallo, E., Hodges-Kluck, E., Shin, J., Jeon, Y., Bae, H., Baldassare, V., Cho, H., Cho, W., Foord, A., et al. 2019, ApJ, 886, 93

Jorstad, S. G., Marscher, A. P., Morozova, D. A., [et. al, including Foord, A.] 2017, ApJ, 846, 98

Foord, A., Gallo, E., Hodges-Kluck, E., Miller, B., Baldassare, V, Gültekin, K., Gnedin, O. 2017, ApJ, 841, 51