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.

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 JHK(s); 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.

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 H-0 = 69.6 0.8 (1.1% stat) 1.7 (2.4% sys) km s(-1) Mpc(-1).

In the nearby galaxy NGC 4258, the well-modeled orbital motion of H2O masers about its supermassive black hole provides the means to measure a precise geometric distance. As a result, NGC 4258 is one of a few "geometric anchors" available to calibrate the true luminosities of stellar distance indicators such as the Tip of the Red Giant Branch (TRGB) or the Cepheid Leavitt law. In this paper, we present a detailed study of the apparent magnitude of the TRGB within NGC 4258, using publicly available HST observations optimally situated in the unreddened stellar halo along the minor axis, spanning distances ranging from 8 to 22 kpc in projected galactocentric radius, or 6' (13 kpc) to 30' (66 kpc) in distance along the semimajor axis. We undertake a systematic evaluation of the uncertainties associated with measuring the TRGB in this galaxy, based on an analysis of 54 arcmin(2) of HST/ACS imaging. After quantifying these uncertainties, we measure the TRGB in NGC 4258 to be F814W(0).=.25.347 +/- 0.014 (stat) +/- 0.042 (sys) mag. Combined with a recent 1.5% megamaser distance to NGC 4258, we determine the absolute luminosity of the TRGB to be M-F814W(TRGB) = - 4.050 .+/- 0.028(stat).+/-.0.048 (sys) mag. This new calibration agrees to better than 1% with an independent calibration presented in Freedman et al. that was based on detached eclipsing binaries (DEBs) located in the LMC.

The primary goal of the Carnegie Chicago Hubble Program (CCHP) is to calibrate the zero-point of the Type Ia supernova (SN Ia) Hubble Diagram through the use of Population II standard candles. So far, the CCHP has measured direct distances to 11 SNe Ia, and here we increase that number to 15 with two new Tip of the Red Giant Branch (TRGB) distances measured to NGC 5643 and NGC 1404. We present resolved, point-source photometry from new Hubble Space Telescope imaging of these two galaxies in the F814W and F606W bandpasses. From each galaxy's stellar halo, we construct an F814W-band luminosity function in which we detect an unambiguous edge feature identified as the TRGB. For NGC 5643, we find mu (0) = 30.48 +/- 0.03(stat) +/- 0.07(sys) mag, and for NGC 1404 we find mu (0) = 31.36 +/- 0.04(stat) +/- 0.05(sys) mag. From a preliminary consideration of the SNe Ia in these galaxies, we find increased confidence in the results presented in Paper VIII. The high precision of our TRGB distances enables a significant measurement of the 3D displacement between the Fornax cluster galaxies NGC 1404 and NGC 1316 (Fornax A) equal to 1.50-0.39+0.25