Cold gas plays a central role in feeding and regulating star formation and growth of supermassive black holes (SMBH) in galaxy nuclei. Particularly powerful activity occurs when interactions of gas-rich galaxies funnel large amounts of gas and dust into nuclei of luminous and ultra luminous infrared galaxies (LIRGs/ULIRGs). These dusty objects are of key importance to galaxy mass assembly over cosmic time. Some (U)LIRGS have deeply embedded galaxy nuclei that harbour a very active evolutionary stage of AGNs and/or starbursts. The nuclear activity will often drive mechanical feedback in the form of molecular winds, jets and outflows. This feedback can for example remove baryons from low-mass galaxies, prevent overgrowth of galaxies, be linked to the M_BH-σ relation, and explain “red-and dead” properties of local ellipticals. With the ALMA and NOEMA telescopes we can use molecules as diagnostic tools to probe the properties of dust-enshrouded galaxy nuclei and their associated cold winds and outflows. Their morphology, velocity structure, physical conditions and even chemistry can be studied at unprecedented sensitivity and resolution, opening new avenues to further our understanding of the growth of galaxies. I will give a brief review of the ALMA/NOEMA view of AGN and starburst radiative and mechanical feedback, and how it is linked to the properties of the nuclear power source. I will discuss the use of molecules (e.g. H₂O, H₃O⁺, HCN, HCO⁺, H₂S) for studying dusty nuclei and the nature of the embedded activity. We can, for example, investigate ionization rates and the impact of cosmic ray-, X-ray- and PDR-chemistry and the onset of outflows and winds. Interestingly, in some deeply obscured nuclei the chemistry shows strong similarities to that of Galactic hot cores. Finally I will show peculiar molecular jets and very recent ALMA observations at resolutions of tens of milli-arcseconds (few pc) of vibrationally excited HCN in opaque nuclei. These regions offer both challenges and opportunities for IR and submm studies of the nature of the buried activity – which we suggest is a deeply dust-enshrouded SMBH in a high-accretion state, or an extreme, high-temperature, burst of star formation.

In a 2500 square degree cosmological survey, the South Pole Telescope has systematically identified a large number (100) of high-redshift strongly gravitationally lensed sub-millimeter galaxies (SMGs). We are conducting a unique spectroscopic redshift survey with ALMA, targeting carbon monoxide (CO) line emission in these sources, across the 3mm spectral window. To date, we have obtained spectroscopic redshifts for 54 sources from 1.8 < z < 6.9, with a median of z=3.9. This sample comprises 70% of the total spectroscopically confirmed SMGs at z > 4 and extends into the epoch of re-ionization. Once we determine the redshift for these sources, we are able to obtain high-resolution CO, [CII], [NII], H₂O, OH, and HCN for these sources with ALMA, making this the largest and most well-studied samples of high-redshift starburst galaxies. We are undertaking a comprehensive and systematic followup campaign to use these "cosmic magnifying glasses" to study the physical conditions and chemical evolution of the dust-obscured universe in unprecedented detail. I will describe our team’s method for obtaining and confirming spectroscopic redshifts, detail our current knowledge of the redshifts distribution of SMGs, present a method for selecting the highest redshift SMGs, describe our high-resolution imaging of molecular lines, and discuss future directions for obtaining large samples of mm-wave spectra.

The study of dusty star forming galaxies (DSFGs) is important to understand galaxy assembly in early universe. A bulk of star formation at z  ∼ 2−3 takes place in DSFGs but are obscured by dust in optical/UV. However, they are extremely bright in far infrared (FIR) and submillimeter with infrared luminosities of 10¹¹ − 10¹³ L_\odot. ALMA, with its high spatial and spectral resolution, has opened up a new window to study molecular lines, which are vital to our understanding of the excitation and physical processes in the galaxy. Carbon monoxide (CO) being the second most abundant and bright molecule after hydrogen (H₂), is an important tracer of star forming potential. Besides CO, water (H₂O) is also abundant and it's line strength is comparable to high-J CO lines in high redshift Ultra Luminous Infrared Galaxies (ULIRGs). Studies have shown H₂O to directly trace the FIR field and hence the star forming regions. Moreover, L_H2O/L_IR ratio is nearly constant for five of the most important water lines and does not depend on the presence of AGN implying that H₂O is one of the best tracers of star forming regions (SFRs). This incredible correlation holds for nearly five orders of magnitude in luminosity and observed in both local and high redshift luminous infrared galaxies.

In this talk, I will discuss the importance of H₂O in tracing FIR field and show the preliminary results of resolved water emission from three high-redshift gravitationally lensed South Pole Telescope (SPT) sources obtained from ALMA cycle 3 and cycle 4. These sources are among the first H₂O observations with resolved spatial scales  ∼ 1 kpc and will prove to be important for ALMA and galaxy evolution studies.

Observations of PO and PN have been carried out at the Arizona Radio Observatory at 1, 2, and 3 mm. Multiple transitions of PO and PN have been detected towards the O-rich AGB stars TX Cam and RCas. Data obtained toward supergiant stars VY Canis Majoris and NML Cyg have also been analyzed. Abundances were obtained for these molecules in all four objects using the radiative transfer code ESCAPADE, which is suitable for symmetric and asymmetric stellar outflows. The abundances of PN and PO were found to be in the range 10⁻⁸ - 10⁻⁷ relative to H₂. While PN appears to be a parent molecule formed by LTE chemistry near the stellar photosphere, PO appears to be created further out from the star at r > 400 R_*.

Silicon bearing molecules account for  ∼  10% of the identified molecules in space. Among those containg hydrogen, SiH and SiH₄ have been identified in the solar spectrum, in some cold stars, and SiH₄ in IRC+1026. However the simple SiH⁺ cation (silylidinium) has only been observed in the solar photosphere and it remains undetected in interstellar space. Most of the spectroscopic information on SiH⁺ comes from the analisis of its vis-UV spectrumA. E. Douglas & B. Lutz, Can. J. Phys. 48 (1970) 247^,T. Carlson et al. Astron. & Astrophys. 83 (1980) 238 and from a diode laser spectrum combined with velocity modulation of the v=1−0 bandP. B. Davies, P. M. Martineau, J. Chem. Phys. 88 (1985) 485 The latter contained just eight lines measured with an estimated accuracy of 0.001 cm⁻¹. We present the results obtained with a difference frequency laser spectrometer coupled to a hollow cathode discharge, with an increased number of lines and improved accuracy (1 10^-4 T. Carlson et al. Astron. Astrophys. 83 (1980) 238,P. B. Davies, P. M. Martineau, J. Chem. Phys. 88 (1985) 485.

r0pt Figure The increased sensitivity and angular resolution of high-altitude ground-based interferometers in the sub-millimeter band has enabled the physics and chemistry of carbon- and oxygen-rich evolved stars to be re-examined at an unprecedented level of detail. Observations of rotational lines in the inner envelope — the region within a few stellar radii of the central star where the molecular seeds of dust are formed — allows one to critically assess models of dust growth. Interferometric observations of the outer envelope provide stringent tests of neutral and ionized molecule formation. All of the astronomical studies are crucially dependent on precise laboratory measurements of the rotational spectra of new species and of vibrationally excited levels of known molecules and their rare isotopic species. By means of a closely coordinated laboratory and astronomical program, a number of exotic species including the disilicon carbide SiCSi, titanium oxides TiO and TiO₂, and carbon chain anions ranging from CN⁻ to C₈H⁻ have recently been observed in evolved stars. This talk will provide overview of these findings, and how they impact current models of the "chemical laboratories" of evolved stars. Ongoing laboratory studies of small silicon-bearing molecules such as H₂SiO₂ and vibrationally excited SiC₂ will be highlighted.

The microwave spectrum of propanal, also known as propionaldehyde, CH₃CH₂CHO, has been investigated in the laboratory already since 1964¹ and has also been detected in space². Recently, propanal was detected with the Atacama Large Millimeter/submillimeter Array (ALMA), Protostellar Interferometric Line Survey (PILS)³. The high sensitivity and resolution of ALMA indicated small discrepancies between observed and predicted rotational spectra of propanal. As higher accuracies are desired the spectrum of propanal was measured up to 500 GHz with the Cologne (Sub-)Millimeter spectrometer. Propanal has two stable conformers, syn and gauche, which differ mainly in the rotation of the aldehyd group with respect to the rigid C-atom framework of the molecule. We extensively studied both of them. The lower syn-conformer shows small splittings caused by the internal rotation of the methyl group, whereas the spectrum of gauche-propanal is complicated due to the tunneling rotation interaction from two stable degenerate conformers. Additionally, we analyzed vibrationally excited states. ¹ Butcher et al., J. Chem. Phys. 40 6 (1964) ² Hollis et al., Astrophys. J. 610 L21 (2004) ³ Lykke et al., A&A 597 A53 (2017)

The ground state of HCCNCS, prepared by high voltage electric discharge of a gas mixture of acetylene and CH₃NCS in neon during supersonic expansion, was studied using both chirped pulse Fourier transform microwave (cp-FTMW) and Balle Flygare FTMW spectrometers. The pure rotational spectra were measured for the parent, ³⁴S, and three ¹³C isotopologues in natural abundance and the ¹⁴N nuclear quadrupole hyperfine structure was resolved. The observed spectra are consistent with a linear or quasilinear ground state of HCCNCS. The corresponding rotational constants were used to derive the substitution (r_s) and effective ground state (r₀) geometries. Supporting calculations at the MP2/cc-pVQZ and CCSD(T)/cc-pVQZ (expanded basis cc-pV(Q+d)Z for sulfur) levels of theory reveal that the potential energy surface is virtually flat around the minimum and yield an equilibrium structure (r_e) that is consistent with experiment.

The glycinamide H₂NCH₂CONH₂, considered as one of the possible precursors of glycine, has been generated in the gas phase via laser ablation of glycinamide hydrochloride. The vaporized products were seeded in neon, expanded adiabatically into the vacuum chamber of the spectrometer and probed by broadband chirped pulsed Fourier transform microwave spectroscopy. The most stable conformer is stabilized by an intramolecular hydrogen bonding interaction between the lone pair on the nitrogen in the amine group and the H-N bond in the amide group was observed in accordance with the previous millimeter wave study Z.Kisiel, E.Białkowska-Jaworska,L.Pszczółkowski,J.C.Guillemin, 21st HRMS, Pozna\'n, 2010. Glycinamide possesses two ¹⁴N nuclei with a nuclear quadrupole moment I=1, which give rise to a complex hyperfine structure. We took advantage of the higher resolution of our narrowband LA-MB-FTMW spectrometer C.Bermudez, S. Mata, C.Cabezas, and J.L.Alonso, Angew. Chem. 2014, 126, 11195–11198.o fully resolve the nuclear quadrupole hyperfine structure. More than 90 nuclear quadrupole hyperfine components belonging to 5 different rotational transitions were analyzed. This provides a definitive evidence to establish the most stable observed conformer.

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Footnotes:

Z.Kisiel, E.Białkowska-Jaworska,L.Pszczółkowski,J.C.Guillemin, 21st HRMS, Pozna\'n, 2010.. C.Bermudez, S. Mata, C.Cabezas, and J.L.Alonso, Angew. Chem. 2014, 126, 11195–11198.t

Among the sugar compounds whose conformations have been determined by different spectroscopic techniques the structure of the lactaldehyde (CH₃CH(OH)CHO), the simplest chiral sugar, is conspicuously absent. It is of great interest in the field of astrophysics, where the ongoing search in the interstellar medium (ISM) has been able to detect, based on the rotational spectra identification, the simplest C₂ sugar glycoaldehyde Hollis JM; Lovas FJ; Jewell. Astrophys J. (2000), 540(2):L107–L110^, Hollis JM; Jewell PR; Lovas FJ; Remijan A. Astrophys J. (2004), 613(1):L45–L48.L

Protonated formaldehyde has been detected in the interstellar medium, where it participates in the formation and destruction of methanol. The rotational spectrum for protonated formaldehyde has been previously recorded by Amano and coworkers from 120-385 GHz using a hollow cathode discharge source for ion production. Additionally, protonated formaldehyde was produced in a supersonic expansion discharge source by Duncan and coworkers, but it was detected using time-of-flight mass spectrometry. Higher frequency spectra would help to guide additional observational studies of protonated formaldehyde using instruments such as the ALMA and SOFIA observatories. As such, we have used a supersonic expansion discharge source to produce protonated formaldehyde, and recorded its spectrum using millimeter-submillimeter direct absorption spectroscopy. The rotational spectrum was recorded from 350-1000 GHz. Here we will present the experimental design, specifically focusing on the optimization of the source for production of organic ions. We will also present the spectroscopic results for protonated formaldehyde and a spectral analysis with associated prediction that can be extended to frequencies above 1 THz.