Observational properties of a Schwarzschild black hole surrounded by a Dehnen-type dark matter halo

Abstract This study investigates the accretion process and observational signatures of thin accretion disks around a Schwarzschild black hole (BH) embedded in a Dehnen-type dark matter (DM) halo. We examine the influence of the density $$\rho _{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> and radius $$r_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>r</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> of the DM halo on key disk properties, including the energy flux, temperature distribution, and emission spectrum. Our results show that all three of these quantities decrease with increasing $$\rho _{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> or $$r_{s}.$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>r</mml:mi> <mml:mi>s</mml:mi> </mml:msub> <mml:mo>.</mml:mo> </mml:mrow> </mml:math> Furthermore, by generating and analyzing both direct and secondary images of the accretion disk, we explore how the observational inclination angle and the DM halo parameters $$\rho _{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> and $$r_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>r</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> affect image profiles. Finally, the observed flux distributions are presented for different inclination angles. Our findings indicate that the accretion disk becomes colder and dimmer as the DM halo parameters increase, highlighting the significant role of DM in shaping BH observables.