A molecular line survey toward the nearby galaxies NGC 1068, NGC 253, and IC 342 at 3 mm with the Nobeyama 45 m radio telescope: The data

Abstract

We present observational data of a molecular line survey toward the nearby galaxies NGC 1068, NGC 253, and IC 342 at the wavelengths of 3 mm (∼85-116 GHz) obtained with the Nobeyama 45 m radio telescope. In IC 342 the line survey with high spectral resolution at the 3 mm region was reported for the first time. NGC 1068 is a nearby gas-rich galaxy with X-rays from an active galactic nucleus (AGN), and NGC 253 and IC 342 are nearby gas-rich galaxies with prototypical starbursts. These galaxies are useful to study the impacts of X-rays and ultraviolet radiation on molecular abundances. The survey was carried out with the resulting rms noise level of a few mK (T * A ). As a result we could obtain almost complete data of these galaxies at the 3 mm region: We detected 19-23 molecular species depending on the galaxies including several new detections (e.g., cyclic-C 3 H 2 in IC 342). We found that the intensities of HCN, CN, and HC 3 N relative to 13 CO are significantly strong in NGC 1068 compared to those in NGC 253 and IC 342. On the other hand, CH 3 CCH was not detected in NGC 1068. We obtained these results with the narrow beam (15 ′′ .2-19 ′′ .1) of the 45 m telescope among the single-dish telescopes, and in particular selectively observed the molecular gas close to the circumnuclear disk (CND) in NGC 1068. Our line intensities in NGC 1068 were compared to those obtained with the IRAM 30 m radio telescope already reported. As a result, the intensity ratio of each line was found to have information on the spatial distribution. Our observations obtained the line intensities and stringent constraints on the upper limit for the three galaxies with such narrow beam, and consequently, the data will be a basis for further observations with high spatial resolution.

HO Puppis: Not a Be Star, but a Newly Confirmed IW And-type Star

“…Two major phenomena of HO Pup, i.e., brightenings and deep dips, were found to be consistent with models proposed by two different teams- Kimura et al (2020a) and Hameury & Lasota (2014). The former team explained the usual status of HO Pup (without presenting the deep dips) based on a tilted accretion disk model inspired by the idea proposed by Kato (2019). The latter team reproduced both the sudden brightening and deep dip by variations of the mass-transfer rate.…”

“…In their study, HO Pup was classified as a dwarf nova (DN) with a unique heartbeat-like oscillation in its photometric variation, known as an IW And-type star. The stars that display IW And-type phenomena represent a new subclassification of Z Cam stars (Kato 2019). The characteristics of IW And-type stars include eclipsing-like transients that happen once in a while, in addition to repeated brightening events seen in their light curves.…”

Spectrometer Using superconductor MIxer Receiver (SUMIRE) for laboratory submillimeter spectroscopy

“…Thanks to continuous development of sensitive receivers as well as wideband and high frequency-resolution spectrometers for radio astronomy, we can now scan a wide range of frequency and observe many spectral lines of various molecular species with reasonable observation time. Taking advantage of this progress, many spectral line surveys have been conducted during the last two decades toward various types of astronomical sources such as hot cores (e.g., Schilke et al 1997;Schilke et al 2001;Tercero et al 2010;Watanabe et al 2015), low-mass protostellar cores (e.g., Caux et al 2011;Watanabe et al 2012;Lindberg et al 2015;Jørgensen et al 2016;Yoshida et al 2019), dark clouds (e.g., Kaifu et al 2004), shocked regions (e.g., Sugimura et al 2011;Yamaguchi et al 2012), Asymptotic Giant Branch stars (e.g., Cernicharo et al 2000), nearby galaxies (e.g., Martín et al 2006;Aladro et al 2015;Takano et al 2019;Watanabe et al 2014;Watanabe et al 2019), and low-metallicity dwarf galaxies (e.g., Nishimura et al 2016a;Nishimura et al 2016b). These studies clearly reveal characteristic chemical composition of each source in an unbiased way, which allows us to discuss chemical and physical processes occurring there in detail.…”

ALMA Spatially Resolved Dense Molecular Gas Survey of Nearby Ultraluminous Infrared Galaxies

“…A trend of elevated HCN emission, relative to HCO + , is observed in (U)LIRGs with luminous AGN signatures, compared to those without (Imanishi & Nakanishi 2014;Izumi et al 2016;Imanishi et al 2016cImanishi et al , 2018bImanishi et al , 2019). An enhanced HCN abundance in AGN-affected dense molecular gas (e.g., Aladro et al 2015;Saito et al 2018;Takano et al 2019;Nakajima et al 2018;Kameno et al 2020;Imanishi et al 2020) is one possibility. However, higher rotational excitation of HCN by warm and dense molecular gas in the vicinity of a luminous AGN than in a starburst is another scenario (Imanishi et al 2018b), because the critical density of HCN is higher by a factor of ∼5 than that of HCO + (Shirley 2015).…”