From 915bb22299a9927fcd3bce8456e4ae0dc99dac90 Mon Sep 17 00:00:00 2001
From: Aaron LI <aly@aaronly.me>
Date: Sun, 30 Jul 2017 10:19:43 +0800
Subject: cluster/halo.py: Add method "calc_brightness_mean()"
Signed-off-by: Aaron LI <aly@aaronly.me>
---
fg21sim/extragalactic/clusters/halo.py | 48 ++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
(limited to 'fg21sim')
diff --git a/fg21sim/extragalactic/clusters/halo.py b/fg21sim/extragalactic/clusters/halo.py
index adc2bc5..9c030a5 100644
--- a/fg21sim/extragalactic/clusters/halo.py
+++ b/fg21sim/extragalactic/clusters/halo.py
@@ -49,6 +49,7 @@ from ...configs import CONFIGS
from ...utils import COSMO
from ...utils.units import (Units as AU,
UnitConversions as AUC)
+from ...utils.convert import Fnu_to_Tb_fast
logger = logging.getLogger(__name__)
@@ -314,6 +315,53 @@ class RadioHalo:
flux = 1e26 * power / (4*np.pi * DL*DL) # [Jy]
return flux
+ def calc_brightness_mean(self, emissivity, frequencies, pixelsize=None):
+ """
+ Calculate the mean surface brightness (power observed per unit
+ frequency and per unit solid angle) at the specified frequencies
+ from emissivity.
+
+ NOTE
+ ----
+ If the solid angle that the radio halo extends is smaller than
+ the specified pixel area, then the halo is assumed to cover a
+ solid angle of 1 pixel.
+
+ Parameters
+ ----------
+ emissivity : float, or 1D `~numpy.ndarray`
+ The synchrotron emissivity at multiple frequencies.
+ Unit: [erg/s/cm^3/Hz]
+ frequencies : float, or 1D `~numpy.ndarray`
+ The frequencies where to calculate the synchrotron emissivity.
+ Unit: [MHz]
+ pixelsize : float, optional
+ The pixel size of the output simulated sky image.
+ Unit: [arcsec]
+
+ Returns
+ -------
+ Tb : float, or 1D `~numpy.ndarray`
+ The mean surface brightness at each frequency.
+ Unit: [K] <-> [Jy/pixel]
+ """
+ omega = np.pi * self.angular_radius**2 # [arcsec^2]
+ if pixelsize:
+ pixelarea = pixelsize ** 2 # [arcsec^2]
+ if omega < pixelarea:
+ omega = pixelarea
+ logger.warning("Halo sky coverage (%.2f [arcsec^2])" % omega,
+ " < pixel area (%.2f [arcsec^2])" % pixelarea)
+
+ flux = self.calc_flux(emissivity)
+ Tb = [Fnu_to_Tb_fast(Fnu, omega, freq)
+ for Fnu, freq in zip(np.array(flux, ndmin=1),
+ np.array(frequencies, ndmin=1))]
+ if len(Tb) == 1:
+ return Tb[0]
+ else:
+ return np.array(Tb)
+
def fp_injection(self, gamma, t=None):
"""
Electron injection (rate) term for the Fokker-Planck equation.
--
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