The characterisation and quantication of ecological interactions, and the construction of species distributions and their associated ecological niches, is of fundamental theoretical and practical importance.
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These results are consistent with the magnetar engine model for FRBs, if magnetars produced from extreme explosions (GRBs/SLSNe) and those from regular channels (e.g., those producing Galactic magnetars) can both produce FRBs. Individually, the host of FRB 121102 is consistent with that of young population objects the environment of FRB 180924 is similar to that of SGRBs and the environment of FRB 190523 is similar to those of SNe Ia. We find that the stellar mass and star formation rate of the FRB host galaxies, taken as a whole sample, prefer a medium to old population, and are against a young population, similar to LGRBs and SLSNe by a null probability of 0.02. We compare the host galaxy properties of nine FRBs with those of several types of stellar transients: from young to old populations, long-duration gamma-ray bursts (LGRBs), superluminous supernovae (SLSNe), SNe Ibc, SNe II, SNe Ia, and short-duration gamma-ray bursts (SGRBs).
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While FRB 121102 resides in the bright region of a dwarf star-forming galaxy, other FRBs reside in more massive galaxies and are related to older stellar populations. Recent arcsecond localizations of fast radio bursts and identifications of their host galaxies confirmed their extragalactic origin. We suggest that the most luminous (in both X-rays and IR) IMPS could be used to place empirical constraints on the location of the intermediate-mass stellar birth line. IMPS therefore provide powerful probes of isochronal ages for the first $\sim$10 Myr in the evolution of a massive stellar population, because their intrinsic, coronal X-ray emission decays rapidly after they commence evolving along radiative tracks. These lines of evidence converge on a magneto-coronal flaring source for IMPS X-ray emission, a scaled-up version of the TTS emission mechanism. We then perform X-ray spectral fitting to determine the hydrogen absorbing column density ($N_$, while AB stars of similar masses have X-ray emission consistent with TTS companions. We divide our sources among these three sub-classifications and further identify disk-bearing young stellar objects versus diskless sources with no detectable infrared (IR) excess emission using IR (1-8 $\mu$m) spectral energy distribution modeling. intermediate-mass T Tauri stars), late-B and A stars on the zero-age main sequence (AB), and lower-mass T Tauri stars (TTS). We use X-ray and infrared observations to study the properties of three classes of young stars in the Carina Nebula: intermediate-mass (2-8M$_\odot$) pre-main sequence stars (IMPS i.e. IMPS therefore provide powerful probes of isochronal ages for the first ∼10 Myr in the evolution of a massive stellar population, because their intrinsic, coronal X-ray emission decays rapidly after they commence evolving along radiative tracks. These lines of evidence converge on a magnetocoronal flaring source for IMPS X-ray emission, a scaled-up version of the TTS emission mechanism.
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IMPS are systematically more luminous in X-rays (by ∼0.3 dex) than all other subclassifications, with median L_X = 2.5 × 10³¹ erg s⁻¹, while AB stars of similar masses have X-ray emission consistent with TTS companions. We find that the X-ray spectra of both IMPS and TTS are characterized by similar kT and N_H, and on average L_X/L_(bol) ∼ 4 × 10−4. We then perform X-ray spectral fitting to determine the hydrogen-absorbing column density (N_H), absorption-corrected X-ray luminosity (L_X), and coronal plasma temperature (kT) for each source. We divide our sources among these three subclassifications and further identify disk-bearing young stellar objects versus diskless sources with no detectable infrared (IR) excess emission using IR (1–8 μm) spectral energy distribution modeling. We use X-ray and infrared observations to study the properties of three classes of young stars in the Carina Nebula: intermediate-mass (2–5 M_⊙) pre-main-sequence stars (IMPS i.e., intermediate-mass T Tauri stars), late-B and A stars on the zero-age main sequence (AB), and lower-mass T Tauri stars (TTS).