DOI: 10.5281/zenodo.8083620
title: The NANOGrav Search for Signals from New Physics: MCMC chains

description: MCMC chains for the GWB analyses performed in the paper "<em>The NANOGrav 15 yr Data Set: Search for Signals from New Physics</em>". The data is provided in pickle format. Each file contains a NumPy array with the MCMC chain (with burn-in already removed), and a dictionary with the model parameters' names as keys and their priors as values. You can load them as <pre><code class="language-python">with open ('path/to/file.pkl', 'rb') as pick: temp = pickle.load(pick) params = temp[0] chain = temp[1]</code></pre> The naming convention for the files is the following: <strong>igw</strong>: inflationary Gravitational Waves (GWs) sigw: scalar-induced GWs <strong>sigw_box</strong>: assumes a box-like feature in the primordial power spectrum. <strong>sigw_delta</strong>: assumes a delta-like feature in the primordial power spectrum. <strong>sigw_gauss</strong>: assumes a Gaussian peak feature in the primordial power spectrum. pt: cosmological phase transitions <strong>pt_bubble</strong>: assumes that the dominant contribution to the GW productions comes from bubble collisions. <strong>pt_sound</strong>: assumes that the dominant contribution to the GW productions comes from sound waves. stable: stable cosmic strings <strong>stable-c</strong>: stable strings emitting GWs only in the form of GW bursts from cusps on closed loops. <strong>stable-k</strong>: stable strings emitting GWs only in the form of GW bursts from kinks on closed loops. <strong>stable</strong>-<strong>m</strong>: stable strings emitting monochromatic GW at the fundamental frequency. <strong>stable-n</strong>: stable strings described by numerical simulations including GWs from cusps and kinks. meta: metastable cosmic strings <strong>meta</strong>-<strong>l</strong>: metastable strings with GW emission from loops only. <strong>meta-ls</strong> metastable strings with GW emission from loops and segments. <strong>super</strong>: cosmic superstrings. dw: domain walls <strong>dw-sm</strong>: domain walls decaying into Standard Model particles. <strong>dw-dr</strong>: domain walls decaying into dark radiation. For each model, we provide four files. One for the run where the new-physics signal is assumed to be the only GWB source. One for the run where the new-physics signal is superimposed to the signal from Supermassive Black Hole Binaries (SMBHB), for these files "_bhb" will be appended to the model name. Then, for both these scenarios, in the "compare" folder we provide the files for the hypermodel runs that were used to derive the Bayes' factors. In addition to chains for the stochastic models, we also provide data for the two deterministic models considered in the paper (ULDM and DM substructures). For the ULDM model, the naming convention of the files is the following (all the ULDM signals are superimposed to the SMBHB signal, see the discussion in the paper for more details) <strong>uldm_e</strong>: ULDM Earth signal. uldm_p: ULDM pulsar signal <strong>uldm_p_cor</strong>: correlated limit <strong>uldm_p_unc</strong>: uncorrelated limit uldm_c: ULDM combined Earth + pulsar signal direct coupling <strong>uldm_c_cor</strong>: correlated limit <strong>uldm_c_unc</strong>: uncorrelated limit uldm_vecB: vector ULDM coupled to the baryon number <strong>uldm_vecB_cor:</strong> correlated limit <strong>uldm_vecB_unc</strong>: uncorrelated limit uldm_vecBL: vector ULDM coupled to B-L <strong>uldm_vecBL_cor:</strong> correlated limit <strong>uldm_vecBL_unc</strong>: uncorrelated limit uldm_c_grav: ULDM combined Earth + pulsar signal for gravitational-only coupling uldm_c_grav_cor: correlated limit <strong>uldm_c_cor_grav_low</strong>: low mass region <strong>uldm_c_cor_grav_mon</strong>: monopole region <strong>uldm_c_cor_grav_low</strong>: high mass region <strong>uldm_c_unc</strong>: uncorrelated limit <strong>uldm_c_unc_grav_low</strong>: low mass region <strong>uldm_c_unc_grav_mon</strong>: monopole region <strong>uldm_c_unc_grav_low</strong>: high mass region For the substructure (static) model, we provide the chain for the marginalized distribution (as for the ULDM signal, the substructure signal is always superimposed to the SMBHB signal)