Abstract
We present a new and independent determination of the local value of the Hubble constant based on a calibration of the tip of the red giant branch (TRGB) applied to Type Ia supernovae ...(SNe Ia). We find a value of
H
0
= 69.8 ± 0.8 (±1.1% stat) ± 1.7 (±2.4% sys) km s
−1
Mpc
−1
. The TRGB method is both precise and accurate and is parallel to but independent of the Cepheid distance scale. Our value sits midway in the range defined by the current Hubble tension. It agrees at the 1.2
σ
level with that of the Planck Collaboration et al. estimate and at the 1.7
σ
level with the
Hubble Space Telescope
(
HST
)
SHoES
measurement of
H
0
based on the Cepheid distance scale. The TRGB distances have been measured using deep
HST
Advanced Camera for Surveys imaging of galaxy halos. The zero-point of the TRGB calibration is set with a distance modulus to the Large Magellanic Cloud of 18.477 ± 0.004 (stat) ± 0.020 (sys) mag, based on measurement of 20 late-type detached eclipsing binary stars, combined with an
HST
parallax calibration of a 3.6
μ
m Cepheid Leavitt law based on
Spitzer
observations. We anchor the TRGB distances to galaxies that extend our measurement into the Hubble flow using the recently completed Carnegie Supernova Project I ( CSP-I ) sample containing about 100 well-observed SNe Ia . There are several advantages of halo TRGB distance measurements relative to Cepheid variables; these include low halo reddening, minimal effects of crowding or blending of the photometry, only a shallow (calibrated) sensitivity to metallicity in the
I
band, and no need for multiple epochs of observations or concerns of different slopes with period. In addition, the host masses of our TRGB host-galaxy sample are higher, on average, than those of the Cepheid sample, better matching the range of host-galaxy masses in the CSP-I distant sample and reducing potential systematic effects in the SNe Ia measurements.
Calibration of the Tip of the Red Giant Branch Freedman, Wendy L.; Madore, Barry F.; Hoyt, Taylor ...
Astrophysical journal/The Astrophysical journal,
03/2020, Volume:
891, Issue:
1
Journal Article
Peer reviewed
Open access
The tip of the red giant branch (TRGB) method provides one of the most accurate and precise means of measuring the distances to nearby galaxies. Here we present a multi-wavelength, VIJHK absolute ...calibration of the TRGB based on observations of TRGB stars in the Large Magellanic Cloud (LMC), grounded on a geometric distance, determined by detached eclipsing binaries (DEBs). This paper presents a more detailed description of the method first presented by Freedman et al. for measuring corrections for the total line-of-sight extinction and reddening to the LMC. In this method, we use a differential comparison of the red giant population in the LMC, first with red giants in the Local Group galaxy IC 1613, and then with those in the Small Magellanic Cloud (SMC). As a consistency check, we derive an independent calibration of the TRGB sequence using the SMC alone, invoking its geometric distance also calibrated by DEBs. An additional consistency check comes from near-infrared observations of Galactic globular clusters covering a wide range of metallicities. In all cases we find excellent agreement in the zero-point calibration. We then examine the recent claims by Yuan et al., demonstrating that, in the case of the SMC, they corrected for extinction alone while neglecting the essential correction for reddening. In the case of IC 1613, we show that their analysis contains an incorrect treatment of (over-correction for) metallicity. Using our revised (and direct) measurement of the LMC TRGB extinction, we find a value of H0 = 69.6 0.8 ( 1.1% stat) 1.7 ( 2.4% sys) km s−1 Mpc−1.
ABSTRACT
RR Lyrae stars have long been popular standard candles, but significant advances in methodology and technology have been made in recent years to increase their precision as distance ...indicators. We present multiwavelength (optical UBVRcIc and Gaia G, BP, RP; near-infrared JHKs; mid-infrared 3.6, 4.5) period–luminosity–metallicity (PLZ), period–Wesenheit–metallicity (PWZ) relations, calibrated using photometry obtained from the Carnegie RR Lyrae Program and parallaxes from the Gaia second data release for 55 Galactic field RR Lyrae stars. The metallicity slope, which has long been predicted by theoretical relations, can now be measured in all passbands. The scatter in the PLZ relations is on the order of 0.2 mag, and is still dominated by uncertainties in the parallaxes. As a consistency check of our PLZ relations, we also measure the distance modulus to the globular cluster M4, the Large Magellanic Cloud and the Small Magellanic Cloud, and our results are in excellent agreement with estimates from previous studies.
This book gives a structured account of Egypt's transition from Ptolemaic to Roman rule by identifying key relationships between ecology, land tenure, taxation, administration and politics. It ...introduces theoretical perspectives from the social sciences and subjects them to empirical scrutiny using data from Greek and Demotic papyri as well as comparative evidence. Although building on recent scholarship, it offers some provocative arguments that challenge prevailing views. For example, patterns of land ownership are linked to population density and are seen as one aspect of continuity between the Ptolemaic and Roman period. Fiscal reform, by contrast, emerges as a significant mechanism of change not only in the agrarian economy but also in the administrative system and the whole social structure. Anyone seeking to understand the impact of Roman rule in the Hellenistic east must consider the well-attested processes in Egypt that this book seeks to explain.
We present a multi-wavelength compilation of new and previously published photometry for 55 Galactic field RR Lyrae variables. Individual studies, spanning a time baseline of up to 30 years, are ...self-consistently phased to produce light curves in 10 photometric bands covering the wavelength range from 0.4 to 4.5 microns. Data smoothing via the GLOESS technique is described and applied to generate high-fidelity light curves, from which mean magnitudes, amplitudes, rise times, and times of minimum and maximum light are derived. 60,000 observations were acquired using the new robotic Three-hundred MilliMeter Telescope (TMMT), which was first deployed at the Carnegie Observatories in Pasadena, CA, and is now permanently installed and operating at Las Campanas Observatory in Chile. We provide a full description of the TMMT hardware, software, and data reduction pipeline. Archival photometry contributed approximately 31,000 observations. Photometric data are given in the standard Johnson UBV, Kron-Cousins , 2MASS JHK, and Spitzer 3.6 and 4.5 bandpasses.
ABSTRACT
We present an overview of the Carnegie-Chicago Hubble Program, an ongoing program to obtain a 3% measurement of the Hubble constant (
H
0
) using alternative methods to the traditional ...Cepheid distance scale. We aim to establish a completely independent route to
H
0
using RR Lyrae variables, the tip of the red giant branch (TRGB), and Type Ia supernovae (SNe Ia). This alternative distance ladder can be applied to galaxies of any Hubble type, of any inclination, and, using old stars in low-density environments, is robust to the degenerate effects of metallicity and interstellar extinction. Given the relatively small number of SNe Ia host galaxies with independently measured distances, these properties provide a great systematic advantage in the measurement of
H
0
via the distance ladder. Initially, the accuracy of our value of
H
0
will be set by the five Galactic RR Lyrae calibrators with
Hubble Space Telescope
Fine-Guidance Sensor parallaxes. With
Gaia
, both the RR Lyrae zero-point and TRGB method will be independently calibrated, the former with at least an order of magnitude more calibrators and the latter directly through parallax measurement of tip red giants. As the first end-to-end “distance ladder” completely independent of both Cepheid variables and the Large Magellanic Cloud, this path to
H
0
will allow for the high-precision comparison at each rung of the traditional distance ladder that is necessary to understand tensions between this and other routes to
H
0
.
Abstract
The Carnegie–Chicago Hubble Program (CCHP) seeks to anchor the distance scale of Type Ia supernovae via the Tip of the Red Giant Branch (TRGB) method. Based on deep
Hubble Space Telescope
...ACS/WFC imaging, we present an analysis of the TRGB for the metal-poor halo of NGC 1365, a giant spiral galaxy in the Fornax cluster that was host to the Type Ia supernova SN 2012fr. We have measured the extinction-corrected TRGB magnitude of NGC 1365 to be
F
814
W
= 27.34 ± 0.03
stat
± 0.04
sys
mag. In advance of future direct calibration by
Gaia
, we adopt a provisional
I
-band TRGB luminosity set at the Large Magellanic Cloud and find a true distance modulus
μ
0
= 31.29 ± 0.04
stat
± 0.06
sys
mag or
D
= 18.1 ± 0.3
stat
± 0.5
sys
Mpc. This measurement is in excellent agreement with recent Cepheid-based distances to NGC 1365 and reveals no significant difference in the distances derived from stars of Populations I and II for this galaxy. We revisit the error budget for the CCHP path to the Hubble constant based on the analysis presented here, i.e., that for one of the most distant Type Ia supernova hosts within our Program, and find that a 2.5% measurement is feasible with the current sample of galaxies and TRGB absolute calibration.
Abstract
The Carnegie–Chicago Hubble Program (CCHP) is recalibrating the extragalactic SN Ia distance scale using exclusively Population II stars. This effort focuses on the Tip of the Red Giant ...Branch (TRGB) method, whose systematics are entirely independent of the Population I Cepheid-based determinations that have long served as calibrators for the SN Ia distance scale. We present deep
Hubble Space Telescope
imaging of the low surface density and low line-of-sight reddening halos of two galaxies, NGC 1448 and NGC 1316, each of which have been hosts to recent SN Ia events. Provisionally anchoring the TRGB zero-point to the geometric distance to the Large Magellanic Cloud derived from detached eclipsing binaries, we measure extinction-corrected distance moduli of
mag for NGC 1448 and
mag for NGC 1316, respectively, giving metric distances of
Mpc, and
Mpc. We find agreement between our result and the available Cepheid distance for NGC 1448; for NGC 1316, where there are relatively few published distances based on direct measurements, we find that our result is consistent with the published SN Ia distances whose absolute scales are set from other locally determined methods such as Cepheids. For NGC 1448 and NGC 1316, our distances are some of the most precise (and systematically accurate) measurements with errors at 1.7 (2.8)% and 1.6 (2.7)% levels, respectively.
We present new theoretical period-luminosity-metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent ...convective hydrodynamical models for a broad range of metal abundances (Z = 0.0001-0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, 0, and extinction, AV, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia's first data release. For M4, we find a distance modulus of 0 = 11.257 0.035 mag with AV = 1.45 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.
Abstract We present near-infrared JHK photometry for the resolved stellar populations in 13 nearby galaxies: NGC 6822, IC 1613, NGC 3109, Sextans B, Sextans A, NGC 300, NGC 55, NGC 7793, NGC 247, NGC ...5253, Cen A, NGC 1313, and M83, acquired from the 6.5 m Baade–Magellan telescope. We measure distances to each galaxy using the J-region asymptotic giant branch (JAGB) method, a new standard candle that leverages the constant luminosities of color-selected, carbon-rich AGB stars. While only single-epoch, random-phase photometry is necessary to derive JAGB distances, our photometry is time-averaged over multiple epochs, thereby decreasing the contribution of the JAGB stars’ intrinsic variability to the measured dispersions in their observed luminosity functions. To cross-validate these distances, we also measure near-infrared tip of the red giant branch (TRGB) distances to these galaxies. The residuals obtained from subtracting the distance moduli from the two methods yield an rms scatter of σ JAGB−TRGB = ±0.07 mag. Therefore, all systematics in the JAGB method and TRGB method (e.g., crowding, differential reddening, star formation histories) must be contained within these ±0.07 mag bounds for this sample of galaxies because the JAGB and TRGB distance indicators are drawn from entirely distinct stellar populations and are thus affected by these systematics independently. Finally, the composite JAGB star luminosity function formed from this diverse sample of galaxies is well described by a Gaussian function with a modal value of M J = –6.20 ± 0.003 mag (stat), indicating that the underlying JAGB star luminosity function of a well-sampled full star formation history is highly symmetric and Gaussian based on over 6700 JAGB stars in the composite sample.
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