autogalaxy.SimulatorInterferometer#

class SimulatorInterferometer[source]#

Bases: SimulatorInterferometer

Simulates observations of Interferometer data, including transforming a real-space image to complex-valued visibilities in Fourier space and optionally adding complex Gaussian noise.

The simulation of an Interferometer dataset uses the following steps:

  1. Receive as input a real-space image (e.g. a model galaxy or lens system) and a set of UV-plane baselines (uv_wavelengths) describing the interferometer configuration.

  2. Fourier transform the real-space image to the UV-plane using the configured transformer class (DFT or NUFFT) to produce model visibilities.

  3. Optionally add complex Gaussian noise to the visibilities, with the noise level controlled by noise_sigma. The noise is added independently to the real and imaginary parts.

  4. Create a constant noise map with value noise_sigma for every visibility. If noise is not added (noise_sigma=None), the noise map is filled with noise_if_add_noise_false instead.

The returned Interferometer dataset contains the simulated visibilities, noise map, uv_wavelengths and real-space mask, and can be used directly with FitInterferometer.

Parameters:

  • uv_wavelengths – The (u, v) baseline coordinates of the interferometer in units of wavelengths. This is a 2D array of shape (total_visibilities, 2) where each row is a (u, v) baseline pair. These define the Fourier-space sampling of the observation.

  • exposure_time (float) – The exposure time of the simulated interferometer observation in seconds.

  • transformer_class – The class used to perform the Fourier transform between real space and the UV-plane. The default TransformerDFT is suitable for small datasets (fewer than ~10,000 visibilities). For larger datasets use TransformerNUFFT for efficiency.

  • noise_sigma – The standard deviation of the complex Gaussian noise added to each visibility. Noise is added independently to the real and imaginary components. If None, no noise is added to the visibilities but a noise map is still created using noise_if_add_noise_false.

  • noise_if_add_noise_false – The noise value assigned to every visibility in the noise map when noise_sigma=None (i.e. when no noise is added to the data). This gives the noise map a non-zero value so that downstream fits remain well-defined.

  • noise_seed – The random seed used for noise generation. A value of -1 uses a different random seed on every run, producing different noise realisations each time.

  • use_jax (bool) – If True, via_image_from defaults xp to jax.numpy and the simulator’s internal complex-Gaussian noise generation routes through jax.random. The returned Interferometer carries jax.Array visibilities. Mirror of SimulatorImaging.use_jax.

__init__(uv_wavelengths, exposure_time, transformer_class=<class 'autoarray.operators.transformer.TransformerDFT'>, noise_sigma=0.1, noise_if_add_noise_false=0.1, noise_seed=-1, use_jax=False)[source]#

Simulates observations of Interferometer data, including transforming a real-space image to complex-valued visibilities in Fourier space and optionally adding complex Gaussian noise.

The simulation of an Interferometer dataset uses the following steps:

  1. Receive as input a real-space image (e.g. a model galaxy or lens system) and a set of UV-plane baselines (uv_wavelengths) describing the interferometer configuration.

  2. Fourier transform the real-space image to the UV-plane using the configured transformer class (DFT or NUFFT) to produce model visibilities.

  3. Optionally add complex Gaussian noise to the visibilities, with the noise level controlled by noise_sigma. The noise is added independently to the real and imaginary parts.

  4. Create a constant noise map with value noise_sigma for every visibility. If noise is not added (noise_sigma=None), the noise map is filled with noise_if_add_noise_false instead.

The returned Interferometer dataset contains the simulated visibilities, noise map, uv_wavelengths and real-space mask, and can be used directly with FitInterferometer.

Parameters:

  • uv_wavelengths – The (u, v) baseline coordinates of the interferometer in units of wavelengths. This is a 2D array of shape (total_visibilities, 2) where each row is a (u, v) baseline pair. These define the Fourier-space sampling of the observation.

  • exposure_time (float) – The exposure time of the simulated interferometer observation in seconds.

  • transformer_class – The class used to perform the Fourier transform between real space and the UV-plane. The default TransformerDFT is suitable for small datasets (fewer than ~10,000 visibilities). For larger datasets use TransformerNUFFT for efficiency.

  • noise_sigma – The standard deviation of the complex Gaussian noise added to each visibility. Noise is added independently to the real and imaginary components. If None, no noise is added to the visibilities but a noise map is still created using noise_if_add_noise_false.

  • noise_if_add_noise_false – The noise value assigned to every visibility in the noise map when noise_sigma=None (i.e. when no noise is added to the data). This gives the noise map a non-zero value so that downstream fits remain well-defined.

  • noise_seed – The random seed used for noise generation. A value of -1 uses a different random seed on every run, producing different noise realisations each time.

  • use_jax (bool) – If True, via_image_from defaults xp to jax.numpy and the simulator’s internal complex-Gaussian noise generation routes through jax.random. The returned Interferometer carries jax.Array visibilities. Mirror of SimulatorImaging.use_jax.

Methods

__init__(uv_wavelengths, exposure_time[, ...])

Simulates observations of Interferometer data, including transforming a real-space image to complex-valued visibilities in Fourier space and optionally adding complex Gaussian noise.

via_galaxies_from(galaxies, grid[, xp])

Returns a realistic simulated image by applying effects to a plain simulated image.

via_image_from(image[, xp])

Simulate an Interferometer dataset from an input real-space image.
via_galaxies_from(galaxies, grid, xp=None)[source]#

Returns a realistic simulated image by applying effects to a plain simulated image.

Parameters:

  • image – The image before simulating (e.g. the lens and source galaxies before optics blurring and Imaging read-out).

  • pixel_scales – The scale of each pixel in arc seconds

  • exposure_time_map – An arrays representing the effective exposure time of each pixel.

  • psf (PSF) – An arrays describing the PSF the simulated image is blurred with.

  • add_poisson_noise_to_data (Bool) – If True poisson noise_maps is simulated and added to the image, based on the total counts in each image pixel

  • noise_seed (int) – A seed for random noise_maps generation