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Title: THE CARNEGIE HUBBLE PROGRAM: THE LEAVITT LAW AT 3.6 AND 4.5 {mu}m IN THE MILKY WAY

Abstract

The Carnegie Hubble Program (CHP) is designed to calibrate the extragalactic distance scale using data from the post-cryogenic era of the Spitzer Space Telescope. The ultimate goal of the CHP is a systematic improvement in the distance scale leading to a determination of the Hubble constant to within an accuracy of 2%. This paper focuses on the measurement and calibration of the Galactic Cepheid period-luminosity (PL, Leavitt) relation using the warm Spitzer/IRAC 1 and 2 bands at 3.6 and 4.5 {mu}m. We present photometric measurements covering the period range 4-70 days for 37 Galactic Cepheids. Data at 24 phase points were collected for each star. Three PL relations of the form M = a(log (P) - 1) + b are derived. The method adopted here takes the slope a to be -3.31, as determined from the Spitzer Large Magellanic Cloud (LMC) data of Scowcroft et al. Using the geometric Hubble Space Telescope guide-star distances to 10 Galactic Cepheids, we find a calibrated 3.6 {mu}m PL zero point of -5.80 {+-} 0.03. Together with our value for the LMC zero point, we determine a reddening-corrected distance modulus of 18.48 {+-} 0.04 mag to the LMC. The mid-IR period-color diagram and themore » [3.6]-[4.5] color variation with phase are interpreted in terms of CO absorption at 4.5 {mu}m. This situation compromises the use of the 4.5 {mu}m data for distance determinations.« less

Authors:
; ; ; ; ;  [1];  [2]
  1. Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  2. Observational Cosmology Lab, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22086380
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 759; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ASTRONOMY; ASTROPHYSICS; CALIBRATION; CARBON MONOXIDE; CEPHEIDS; COLOR; DISTANCE; INFRARED SPECTRA; INTERGALACTIC SPACE; INTERMEDIATE INFRARED RADIATION; LUMINOSITY; MAGELLANIC CLOUDS; MILKY WAY; TELESCOPES

Citation Formats

Monson, Andrew J., Freedman, Wendy L., Madore, Barry F., Persson, S. E., Scowcroft, Victoria, Seibert, Mark, and Rigby, Jane R., E-mail: amonson@obs.carnegiescience.edu, E-mail: wendy@obs.carnegiescience.edu, E-mail: barry@obs.carnegiescience.edu, E-mail: persson@obs.carnegiescience.edu, E-mail: vs@obs.carnegiescience.edu, E-mail: mseibert@obs.carnegiescience.edu, E-mail: Jane.R.Rigby@nasa.gov. THE CARNEGIE HUBBLE PROGRAM: THE LEAVITT LAW AT 3.6 AND 4.5 {mu}m IN THE MILKY WAY. United States: N. p., 2012. Web. doi:10.1088/0004-637X/759/2/146.
Monson, Andrew J., Freedman, Wendy L., Madore, Barry F., Persson, S. E., Scowcroft, Victoria, Seibert, Mark, & Rigby, Jane R., E-mail: amonson@obs.carnegiescience.edu, E-mail: wendy@obs.carnegiescience.edu, E-mail: barry@obs.carnegiescience.edu, E-mail: persson@obs.carnegiescience.edu, E-mail: vs@obs.carnegiescience.edu, E-mail: mseibert@obs.carnegiescience.edu, E-mail: Jane.R.Rigby@nasa.gov. THE CARNEGIE HUBBLE PROGRAM: THE LEAVITT LAW AT 3.6 AND 4.5 {mu}m IN THE MILKY WAY. United States. doi:10.1088/0004-637X/759/2/146.
Monson, Andrew J., Freedman, Wendy L., Madore, Barry F., Persson, S. E., Scowcroft, Victoria, Seibert, Mark, and Rigby, Jane R., E-mail: amonson@obs.carnegiescience.edu, E-mail: wendy@obs.carnegiescience.edu, E-mail: barry@obs.carnegiescience.edu, E-mail: persson@obs.carnegiescience.edu, E-mail: vs@obs.carnegiescience.edu, E-mail: mseibert@obs.carnegiescience.edu, E-mail: Jane.R.Rigby@nasa.gov. Sat . "THE CARNEGIE HUBBLE PROGRAM: THE LEAVITT LAW AT 3.6 AND 4.5 {mu}m IN THE MILKY WAY". United States. doi:10.1088/0004-637X/759/2/146.
@article{osti_22086380,
title = {THE CARNEGIE HUBBLE PROGRAM: THE LEAVITT LAW AT 3.6 AND 4.5 {mu}m IN THE MILKY WAY},
author = {Monson, Andrew J. and Freedman, Wendy L. and Madore, Barry F. and Persson, S. E. and Scowcroft, Victoria and Seibert, Mark and Rigby, Jane R., E-mail: amonson@obs.carnegiescience.edu, E-mail: wendy@obs.carnegiescience.edu, E-mail: barry@obs.carnegiescience.edu, E-mail: persson@obs.carnegiescience.edu, E-mail: vs@obs.carnegiescience.edu, E-mail: mseibert@obs.carnegiescience.edu, E-mail: Jane.R.Rigby@nasa.gov},
abstractNote = {The Carnegie Hubble Program (CHP) is designed to calibrate the extragalactic distance scale using data from the post-cryogenic era of the Spitzer Space Telescope. The ultimate goal of the CHP is a systematic improvement in the distance scale leading to a determination of the Hubble constant to within an accuracy of 2%. This paper focuses on the measurement and calibration of the Galactic Cepheid period-luminosity (PL, Leavitt) relation using the warm Spitzer/IRAC 1 and 2 bands at 3.6 and 4.5 {mu}m. We present photometric measurements covering the period range 4-70 days for 37 Galactic Cepheids. Data at 24 phase points were collected for each star. Three PL relations of the form M = a(log (P) - 1) + b are derived. The method adopted here takes the slope a to be -3.31, as determined from the Spitzer Large Magellanic Cloud (LMC) data of Scowcroft et al. Using the geometric Hubble Space Telescope guide-star distances to 10 Galactic Cepheids, we find a calibrated 3.6 {mu}m PL zero point of -5.80 {+-} 0.03. Together with our value for the LMC zero point, we determine a reddening-corrected distance modulus of 18.48 {+-} 0.04 mag to the LMC. The mid-IR period-color diagram and the [3.6]-[4.5] color variation with phase are interpreted in terms of CO absorption at 4.5 {mu}m. This situation compromises the use of the 4.5 {mu}m data for distance determinations.},
doi = {10.1088/0004-637X/759/2/146},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}