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Register a new userType II Supernovae as Distance Indicators at Near-IR Wavelengths
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Added by
\\'Osmar Rodr\\'iguez
Publication date
2018
fields
Physics
and research's language is
English
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Motivated by the advantages of observing at near-IR wavelengths, we investigate Type II supernovae (SNe II) as distance indicators at those wavelengths through the Photospheric Magnitude Method (PMM). For the analysis, we use $BVIJH$ photometry and optical spectroscopy of 24 SNe II during the photospheric phase. To correct photometry for extinction and redshift effects, we compute total-to-selective broadband extinction ratios and $K$-corrections up to $z=0.032$. To estimate host galaxy colour excesses, we use the colour-colour curve method with the $V!-!I$ versus $B!-!V$ as colour combination. We calibrate the PMM using four SNe II in galaxies having Tip of the Red Giant Branch distances. Among our 24 SNe II, nine are at $cz>2000$ km s$^{-1}$, which we use to construct Hubble diagrams (HDs). To further explore the PMM distance precision, we include into HDs the four SNe used for calibration and other two in galaxies with Cepheid and SN Ia distances. With a set of 15 SNe II we obtain a HD rms of 0.13 mag for the $J$-band, which compares to the rms of 0.15-0.26 mag for optical bands. This reflects the benefits of measuring PMM distances with near-IR instead of optical photometry. With the evidence we have, we can set the PMM distance precision with $J$-band below 10 per cent with a confidence level of 99 per cent.
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Type II Cepheids are both useful distance indicators and tracers of old age stellar populations in their host galaxy. We summarize near-infrared observations of type II Cepheids in the Large Magellanic Cloud and discuss the absolute calibration of their Period-Luminosity relations. Combining with the near-infrared data for type II Cepheids in the Galactic bulge from the VISTA VVV survey, we estimated a robust distance to the Galactic center. We found that type II Cepheids trace the spherically symmetric spatial distribution with possible evidence of ellipsoidal structure, similar to RR Lyrae stars. Together with Gaia and VVV proper motions, type II Cepheids were found to trace the old, metal-poor, kinematically hot stellar populations in the Galactic bulge.
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