Expectations for Horizon-Scale Supermassive Black Hole Population Studies with the ngEHT
Abstract
:1. Introduction
- the angular size of the SMBH shadow ();
- the total horizon-scale flux density emitted by the source (); and
- the optical depth of the emitting material.
2. Measurable Proxies for Quantities of Interest
2.1. Proxy for SMBH Shadows
2.2. Proxy for SMBH Masses
2.3. Proxy for SMBH Spins
3. Synthetic Data Generation and Fitting Procedure
4. Results: The Expected Number of Measurable SMBH Masses, Spins, and Shadows
- Our condition for whether a SMBH has a measurable mass is that the fractional uncertainty in the measurement of the ring diameter d must be at the level of 20% or lower (i.e., it is measured with a statistical significance ). Values of for which this condition is satisfied fall to the upper right of the red dashed curve in Figure 3.
- Our condition for whether a SMBH has a measurable spin is that the uncertainty in the measurement of all spin-relevant parameters (as determined by Qiu et al. [26]; see also Section 2.3) must be at the level of 20% or lower. Specifically, we require the fractional uncertainty in , , and and the uncertainty in and to all be less than 0.2 (i.e., 20%). Values of for which this condition is satisfied fall to the upper right of the green dashed curve in Figure 3.
- Our condition for whether a SMBH has a measurable shadow is that the fractional width deviates from unity with an uncertainty of 20% or smaller; i.e., we require that with a statistical significance . Values of for which this condition is satisfied fall to the upper right of the blue dashed curve in Figure 3.
5. Summary and Conclusions
Author Contributions
Funding
Conflicts of Interest
1 | The procedure Pesce et al. [19] used to determine the number of observable SMBHs involves integrating the supermassive black hole mass function (BHMF) to determine how many objects have shadow diameters larger than , while also using a semi-analytic spectral energy distribution model and adopting an empirically motivated prescription for the SMBH Eddington ratio distribution function to restrict the objects under consideration to those that have flux densities greater than and accretion flows that are optically thin. The distribution of sources used in this paper assumes an observing frequency of 230 GHz and a BHMF determined using the stellar mass function from Behroozi et al. [20] scaled according to the relation determined by Kormendy and Ho [21] (i.e., the “upper BHMF” from Pesce et al. [19]). |
2 | |
3 | |
4 | https://github.com/Smithsonian/ngehtsim, accessed on 5 November 2022. |
5 | https://github.com/aeb/ngEHTforecast, accessed on 5 November 2022. |
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Pesce, D.W.; Palumbo, D.C.M.; Ricarte, A.; Broderick, A.E.; Johnson, M.D.; Nagar, N.M.; Natarajan, P.; Gómez, J.L. Expectations for Horizon-Scale Supermassive Black Hole Population Studies with the ngEHT. Galaxies 2022, 10, 109. https://doi.org/10.3390/galaxies10060109
Pesce DW, Palumbo DCM, Ricarte A, Broderick AE, Johnson MD, Nagar NM, Natarajan P, Gómez JL. Expectations for Horizon-Scale Supermassive Black Hole Population Studies with the ngEHT. Galaxies. 2022; 10(6):109. https://doi.org/10.3390/galaxies10060109
Chicago/Turabian StylePesce, Dominic W., Daniel C. M. Palumbo, Angelo Ricarte, Avery E. Broderick, Michael D. Johnson, Neil M. Nagar, Priyamvada Natarajan, and José L. Gómez. 2022. "Expectations for Horizon-Scale Supermassive Black Hole Population Studies with the ngEHT" Galaxies 10, no. 6: 109. https://doi.org/10.3390/galaxies10060109
APA StylePesce, D. W., Palumbo, D. C. M., Ricarte, A., Broderick, A. E., Johnson, M. D., Nagar, N. M., Natarajan, P., & Gómez, J. L. (2022). Expectations for Horizon-Scale Supermassive Black Hole Population Studies with the ngEHT. Galaxies, 10(6), 109. https://doi.org/10.3390/galaxies10060109