This is the README file that accompanies the v1.0 public release of spectral energy distributions (SEDs) and JWST/NIRCam wideband fluxes from the LYCAN project. The v1.0 grid contains spectra predicted by the Yggdrasil spectral synthesis code (Zackrisson et al. 2011, ApJ 740, 13) for z=7 galaxies extracted from 4 different suites of cosmological simulations (labeled CROC/FiBY/Finlator/Shimizu in the following). In total, this grid features almost 1400 unique simulated galaxies in the ~1e7-1e10 Msolar stellar mass range. Please note that these galaxies have been selected from the high-mass end of the full mass distribution of each simulation suite, and that the least massive galaxies included here do not reflect the any kind of resolution limit in these simulations. Each simulataed galaxy comes with a unique star formation history and metallicity distribution, and several options concerning the dust attenuation recipe are offered for each such object. ---------- SED details --------- -------------------------------- All SEDs in the v1.0 grid are based on: - Starburst99 (Leitherer et al. 1999, ApJS, 123, 3) stellar population spectra generated using Geneva high-mass loss tracks in the Z=0.001-0.040 range and under the assumption of a Kroupa (2001, MNRAS, 322, 231) stellar IMF - Raiter et al. (2010) stellar population spectra for extremely-metal poor stars (Z=1e-7, 1e-5) rescaled to match the Kroupa (2001) stellar IMF - A photoionized nebula predicted by Cloudy (Ferland et al. 1998, PASP, 110, 761) with the option of Lyman continuum leakage by means of holes through an otherwise complete Strömgren sphere (Zackrisson et al. 2013, ApJ, 777, 39). The rest-frame wavelength coverage of the downloadable SEDs is 1230-25000 Å. Hence the Lyman-alpha line (1216 Å) is not included, since the observable strength of this line hinges more on the properties of the intergalactic medium at z=7 than on the ionizing continuum of the galaxy. The NIRCam wideband fluxes are based on the assumption of zero Lyman alpha escape fraction and a complete Gunn-Peterson trough at wavelengths below 1216 Å. A LCDM cosmology with H0=72 km/s/Mpc, Omega_M=0.27, Omega_Lambda=0.73 has been adopted in the derivation of luminosity distances. Dust has been added to all SEDs using the Finlator et al. (2006, ApJ, 639, 672) dust recipe with the Calzetti et al. (2000, ApJ, 533, 682) dust attenuation law (i.e. E(B-V)_stars=0.44*E(B-V)_nebula) and Pei (1992, ApJ 395, 130) Large Magellanic Cloud attenuation law. Additional spectra are available for the Shimizu simulations where dust has been calculated according to the dust recipe presented in Shimizu et al. (2014, MNRAS, 440, 731). The SEDs have been generated with various Lyman continuum escape fractiosn - please see the info next to each data link for details. The stellar population masses listed in the SED files correspond to the total gas mass that has gone into star formation within each individual galaxy. No correction for stellar mass loss or stars that no longer contribute to the light of the galaxy has been made. ---------- How to cite --------- -------------------------------- If you use LYCAN data in your publication, please cite in approximately the following way: "(...) SED models from the LYCAN project (Zackrisson et al. 2017, ApJ 836, 78), based on the galaxy simulations of XXX" where XXX should be replaced by one (or more) of the following, depending on what model batches you are using: CROC - Gnedin, N. 2014, ApJ, 793, 29 FiBY - Paardekooper, J.P. et al. 2015, MNRAS, 451, 2544 Finlator - Finlator, K et al. 2013 MNRAS 436, 1818 Shimizu - Shimizu, I., et al. 2014, MNRAS, 440, 731 Please note that if you want to use the Jensen et al. (2016) SEDs, which contain observational noise relevant for JWST/NIRSPec and various amounts of LyC leakage, you should also cite that paper: Jensen, H., et al. 2016, ApJ, 827, 5 ------------Filenames------------ --------------------------------- Each simulation batch (CROC/FiBY/Finlator/Shimizu) contains two sets of files with prefixes: SED - containing noise-free, rest-frame spectral energy distributions JWST_NIRCam_ABmag - containing JWST/NIRCam wideband fluxes relevant for the redshift in question The string following the prefix describes other properties of the model: Prefix_Simulation_redshift_evolutionarytrack_fesc_dustrecipe_attenuationlaw.txt --------File Headers----------- ------------------------------- Each SED file header starts with information about the population of galaxies, from top down: -Redshift -Infile -Number of galaxies in the file -Interpolation option for SED -dust recipe -attenuation law Then every galaxy spectrum has its own header containing: -SPH galaxy number -Total stellar mass -Total stellar metallicity -LyC escape fraction -Dust attenuation in E(B-V) After that follows two columns with wavelengths and fluxes (the SED). A blank row separates the SED from the next galaxy header. Each photometry file contains the following entries: -Redshift -SPH galaxy number -Total stellar mass AB magnitudes in the following NIRCam filters: F070W, F090W, F115W, F150W, F200W, F277W, 356W, F444W Please note that a magnitude entry of 999.000 is a flag for zero flux. This for instance happens in the F070W filter at z=7, since this filter just captures flux shortward of Lyman alpha (the Gunn-Peterson trough) at this redshift. -----------IMPORTANT NOTE-------------- --------------------------------------- When using the Pei92_LMC dust recipe, a number of wavelength data points fall outside the range inside which the Pei (1992) attenuation law is defined. These points are the first two in every spectrum, meaning 1.22907e+03 Å 1.24018e+03 Å For this reason, the dust attenuation in those points was assumed to be the same as the first point in the interval defined by Pei (1992).