The high energy X-ray probe (HEX-P): bringing the cosmic X-ray background into focus

• DOI: 10.3389/fspas.2024.1340719
• Publication Date: 2024-03-18T04:28:41Z
• Authors: F. Civano; X. Zhao; P. G. Boorman; S. Marchesi; T. Ananna; S. Creech; C.-T. Chen; R. C. Hickox; D. Stern; K. Madsen; J. A. García; R. Silver; J. Aird; D. M. Alexander; M. Baloković; W. N. Brandt; J. Buchner; P. Gandhi; E. Kammoun; S. LaMassa; G. Lanzuisi; A. Merloni; A. Moretti; K. Nandra; E. Nardini; A. Pizzetti; S. Puccetti; R. W. Pfeifle; C. Ricci; D. Spiga; N. Torres-Albà
• Keywords: X-ray background

Since the discovery of cosmic X-ray background (CXB), astronomers have strived to understand accreting supermassive black holes (SMBHs) contributing its peak in 10–40 keV band. Existing soft telescopes could study this population up only 10 keV, and, while NuSTAR (focusing on 3–24 keV) made great progress, it also left significant uncertainties characterizing hard population, crucial for calibrating current synthesis models. This paper presents an in-depth analysis simulations two extragalactic surveys (deep and wide) with High-Energy Probe ( HEX-P ), each observed 2 Ms. Applying established source detection techniques, we show that will reach a flux <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mo>∼</mml:mo><mml:mn>1</mml:mn><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>15</mml:mn></mml:mrow></mml:msup></mml:math> erg s −1 cm −2 band, order magnitude fainter than surveys. With large sample new detected sources id="m2"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>∼</mml:mo><mml:mn>2000</mml:mn></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math> , showcase ’s ability resolve more 80% CXB 40 into individual sources. The expected precision resolved measurement allow us distinguish between models SMBH growth. leverage accurate broadband (0.5–40 spectral combination colors provide obscuration constraints even sources, overall objective measuring Compton-thick fraction. unprecedented sensitivity explore emission from AGN limits never reached before, thus expanding parameter space serendipitous discoveries. Consequently, is plausible be needed capture unveil.