The Carnegie-Chicago Hubble Program (CCHP) seeks to anchor the distance scale of Type la 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 la supernova SN 2012fr. We have measured the extinction-corrected TRGB magnitude of NGC 1365 to be F814W = 27.34 +/- 0.03(stat) +/- 0.04(sys) mag. In advance of future direct calibration by Gala, we adopt a provisiona I-band TRGB luminosity set at the Large Magellanic Cloud and find a true distance modulus mu(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 la supernova hosts within our Program, and find that a 2.5% measurement is feasible with the current sample of galaxies and TRGB absolute calibration.

Based on observations from the FourStar near-infrared camera on the 6.5 m Baade-Magellan telescope at Las Campanas, Chile, we present calibrations of the JHK luminosities of stars defining the tip of the red giant branch (TRGB) in the halo of the Local Group dwarf galaxy IC 1613. We employ metallicity-independent (rectified) T-band magnitudes-constructed using J-, H-, and K-band magnitudes and both (J - H) and (J - K) colors to flatten the upward-sloping red giant branch tips as otherwise seen in their apparent color-magnitude diagrams. We describe and quantify the advantages of working at these particular near-infrared wavelengths, which are applicable to both the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST). We also note that these same wavelengths can be accessed from the ground for an eventual tie-in to Gaia for absolute astrometry and parallaxes to calibrate the intrinsic luminosity of the TRGB. Adopting the color terms derived from the IC 1613 data, as well as the zero points from a companion study of the Large Magellanic Cloud, whose distance is anchored to the geometric distances of detached eclipsing binaries, we find a true distance modulus of 24.32. +/- 0.02. (statistical) +/- 0.05. mag (systematic) for IC 1613, which compares favorably with the recently published multi-wavelength, multi-method consensus modulus of 24.30 +/- 0.05. mag by Hatt et al.

The Carnegie-Chicago Hubble Program is undertaking a re-calibration of the extragalactic distance scale, using SNe Ia that are tied to Tip of the Red Giant Branch (TRGB) distances to local galaxies. We present here deep Hubble Space Telescope ACS/WFC imaging of the resolved stellar populations in the metal-poor halos of the SN. Ia-host galaxies NGC 4424, NGC 4526, and NGC 4536. These three Virgo constellation galaxies are prime targets for calibrating the extragalactic distance scale given their relative proximity in the local universe and their low line-of-sight reddenings. Anchoring the TRGB zero-point to the geometric distance to the Large Magellanic Cloud via detached eclipsing binaries, we measure extinction-corrected distance moduli of 31.00 +/- 0.03(stat) +/- 0.06(sys) mag, 30.98 +/- 0.03(stat) +/- 0.06(sys) mag, and 30.99 +/- 0.03(stat) +/- 0.06(sys) mag for NGC 4424, NGC 4526, and NGC 4536, respectively, or 15.8 +/- 0.2(stat) +/- 0.4(sys) Mpc, 15.7 +/- 0.2(stat) +/- 0.4(sys) Mpc, and 15.8. +/-. 0.2stat. +/-. 0.4sys Mpc. For these three galaxies, the distances are the first that are based on the TRGB, and for NGC 4424 and NGC 4526, they are the highest-precision distances published to date, each measured to 3%. Finally, we report good agreement between our TRGB distances and the available Cepheid distances for NGC 4424 and NGC 4536, demonstrating consistency between the distance scales currently derived from stars of Population I and II.

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 31.23 +/- 0.04(stat )+/- 0.06(sys) mag for NGC 1448 and 31.37 +/- 0.04(stat) +/- 0.06(sys) mag for NGC 1316, respectively, giving metric distances of 17.7 +/- 0.3(stat) +/- 0.5(sys) Mpc, and 18.8 +/- 0.3(stat) +/- 0.5(sys) 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 a new empirical JHK absolute calibration of the tip of the red giant branch (TRGB) in the Large Magellanic Cloud (LMC). We use published data from the extensive Near-Infrared Synoptic Survey containing 3.5 million stars, 65,000 of which are red giants that fall within one magnitude of the TRGB. Adopting the TRGB slopes from a companion study of the isolated dwarf galaxy IC 1613, as well as an LMC distance modulus of mu(0) - 18.49 mag from (geometric) detached eclipsing binaries, we derive absolute JHK zero points for the near-infrared TRGB. For a comparison with measurements in the bar alone, we apply the calibrated JHK TRGB to a 500 deg(2) area of the 2MASS survey. The TRGB reveals the 3D structure of the LMC with a tilt in the direction perpendicular to the major axis of the bar, which is in agreement with previous studies.

We detect widespread [C II] 157.7 mu m emission from the inner 5 kpc of the active galaxy NGC 4258 with the SOFIA integral field spectrometer FIFI-LS. The emission is found to be associated with warm H-2, distributed along and beyond the end of the southern jet, in a zone known to contain shock-excited optical filaments. It is also associated with soft X-ray hotspots, which are the counterparts of the "anomalous radio arms" of NGC 4258, and a 1 kpc long filament on the minor axis of the galaxy that contains young star clusters. Palomar CWI H alpha integral field spectroscopy shows that the filament exhibits non-circular motions within NGC 4258. Many of the [C II] profiles are very broad, with the greatest line width, 455 km s(-1), observed at the position of the southern jet bow-shock. Abnormally high ratios of L([C II])/L(FIR) and L([C II])/L(PAH 7.7 mu m) are found along and beyond the southern jet and in the X-ray hotspots. These are the same regions that exhibit unusually large intrinsic [C II] line widths. This suggests that the [C II] traces warm molecular gas in shocks and turbulence associated with the jet. We estimate that as much as 40% (3.8 x 10(39) erg s(-1)) of the total [C II] luminosity from the inner 5 kpc of NGC 4258 arises in shocks and turbulence (<1% bolometric luminosity from the active nucleus), the rest being consistent with [C II] excitation associated with star formation. We propose that the highly inclined jet is colliding with, and being deflected around, dense irregularities in a thick disk, leading to significant energy dissipation over a wide area of the galaxy.

The role of feedback in triggering or quenching star formation and hence driving galaxy evolution. can be directly studied with high-resolution integral field observations. The manifestation of feedback in shocks is particularly important to examine in galaxy mergers, where violent interactions of gas take place in the interstellar medium during the course of the galactic collision. As part of. our effort to systematically study the local population of luminous infrared galaxies within the Great Observatories All-Sky LIRG Survey, we undertook. the Keck OSIRIS AO LIRG Analysis observing campaign to study the gas dynamics. in the inner kiloparsec regions of these systems at. spatial scales of a few tens of pc. With high-resolution near-infrared adaptive optics-assisted integral field observations taken with OSIRIS on the Keck Telescopes, we employ near-infrared diagnostics such as. Br gamma and the rovibrationally excited H-2. lines to quantify the nuclear star formation rate and identify feedback associated with shocked molecular gas seen in 21 nearby luminous infrared galaxies. Shocked molecular gas is preferentially found in the ultraluminous infrared systems but may also be triggered at a lower-luminosity, earlier merging stage. On circumnuclear scales, AGNs have a strong effect on heating the surrounding molecular gas, though their coupling is not simply driven by AGN strength but rather is complicated by orientation, dust shielding, density, and other factors. We find that nuclear star formation correlates with. merger class and diminishing projected nuclear separations. These trends are largely consistent with the picture of merger-induced starbursts in the center of galaxy mergers.

We present a systematic study of the diffuse ionized gas (DIG) in M83 and its effects on the measurement of metallicity gradients at varying resolution scales. Using spectrophotometric data cubes of M83 obtained at the 2.5m duPont telescope at Las Campanas Observatory as part of the TYPHOON programme, we separate the H II regions from the DIG using the [S II]/H alpha ratio, HIIPHOT (H II-finding algorithm), and the H alpha surface brightness. We find that the contribution to the overall H alpha luminosity is approximately equal for the HII and DIG regions. The data is then rebinned to simulate low-resolution observations at varying resolution scales from 41 pc up to 1005 pc. Metallicity gradients are measured using five different metallicity diagnostics at each resolution. We find that all metallicity diagnostics used are affected by the inclusion of DIG to varying degrees. We discuss the reasons why the metallicity gradients are significantly affected by DIG using the HII dominance and emission line ratio radial profiles. We find that applying the [S II]/H alpha cut will provide a closer estimate of the true metallicity gradient up to a resolution of 1005 pc for all metallicity diagnostics used in this study.

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 sigma level with that of the Planck Collaboration et al. estimate and at the 1.7 sigma 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 HSTparallax calibration of a 3.6 mu 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.

We determine the distances to the Type Ia supernova host galaxies M66 (NGC 3627) and M96 (NGC 3368) of the Leo I Group using the Tip of the Red Giant Branch (TRGB) method. We target the stellar halos of these galaxies using the Hubble Space Telescope ACS/WFC in the F606W and F814W bandpasses. By pointing to the stellar halos we sample RGB stars predominantly of Population II, minimize host-galaxy reddening, and significantly reduce the effects of source crowding. Our absolute calibration of the I-band TRGB is based on a recent detached eclipsing binary distance to the Large Magellanic Cloud. With this geometric zero-point in hand, we find for M66 and M96, respectively, true distance moduli mu(0) = 30.23 +/- 0.04 (stat) +/- 0.06 (sys) mag and mu(0) = 30.29 +/- 0.02 (stat) +/- 0.06 (sys) mag.