Chemical templates of the Central Molecular Zone. Shock and protostellar object signatures under Galactic Center conditions

Abstract

(Abridged) The Central Molecular Zone (CMZ) of the Milky Way exhibits extreme conditions, including high gas densities, elevated temperatures, enhanced cosmic-ray ionization rates, and large-scale dynamics. Large-scale molecular surveys reveal increasing chemical and physical complexity in the CMZ. A key step to interpreting the molecular richness found in the CMZ is to build chemical templates tailored to its diverse conditions. The combined impact of high ionization, elevated temperatures, and dense gas remains insufficiently explored for observable tracers. In this study, we utilized UCLCHEM, a gas-grain time-dependent chemical model, to link physical conditions with their corresponding molecular signatures and identify key tracers of temperature, density, ionization, and shock activity. We ran a grid of models of shocks and protostellar objects representative of typical CMZ conditions, focusing on twenty-four species, including complex organic molecules. Shocked and protostellar environments show distinct evolutionary timescales ($\lesssim 10^4$ vs. $\gtrsim 10^4$ years), with 300 K emerging as a key temperature threshold for chemical differentiation. We find that cosmic-ray ionization and temperature are the main drivers of chemical trends. HCO${}^{+}$, H${}_2$CO, and CH${}_3$SH trace ionization, while HCO, HCO${}^{+}$, CH${}_3$SH, CH${}_3$NCO, and HCOOCH${}_3$ show consistent abundance contrasts between shocks and protostellar regions over similar temperature ranges. While our models underpredict some complex organics in shocks, they reproduce observed trends for most species, supporting scenarios involving recurring shocks in Galactic Center clouds and enhanced ionization towards Sgr B2(N2). Future work should assess the role of shock recurrence and metallicity in shaping chemistry.

arXiv commentAccepted for publication in A&A. 23 pages, 12 figures

References in corpus (97)

• The chemical composition of the Sun
• The Formation of Massive Stars from Turbulent Cores
• The UMIST database for astrochemistry 2012
• A Unified Representation of Gas-Phase Element Depletions in the Interstellar Medium
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• A three-phase chemical model of hot cores: the formation of glycine
• Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
• Variations in the Galactic star formation rate and density thresholds for star formation
• Evaporation of ices near massive stars: models based on laboratory TPD data
• Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate
• Astrochemistry During the Formation of Stars
• Dense gas in the Galactic central molecular zone is warm and heated by turbulence
• The largest oxigen bearing organic molecule repository
• Spatial distribution of interstellar gas in the innermost 3 kpc of our Galaxy
• Magnetic Fields in High-Mass Infrared Dark Clouds
• Modeling Sulfur Depletion in Interstellar Clouds
• Formation of complex organic molecules in hot molecular cores through nondiffusive grain-surface and ice-mantle chemistry
• Re-exploring Molecular Complexity with ALMA (ReMoCA): Interstellar detection of urea
• Astrochemistry of dust, ice and gas: introduction and overview
• Parametrization of C-shocks. Evolution of the Sputtering of Grains
• Molecules at z=0.89: A 4-mm-rest-frame absorption line survey toward PKS 1830-211
• A protostellar system fed by a streamer of 10,500 au length
• SiO emission from the Galactic Center Molecular Clouds
• The Green Bank Ammonia Survey (GAS): First Results of NH3 mapping the Gould Belt
• The physical and chemical structure of Sagittarius B2, I. Three-dimensional thermal dust and free-free continuum modeling on 100 au to 45 pc scales
• Complex organic molecules in the Galactic Centre: the N-bearing family
• Tracing shocks and photodissociation in the Galactic center region
• Comparing molecular gas across cosmic time-scales: the Milky Way as both a typical spiral galaxy and a high-redshift galaxy analogue
• UCLCHEM: A Gas-Grain Chemical Code
• Sulphur chemistry in the L1544 pre-stellar core
• CN and HNC Line Emission in IR Luminous Galaxies
• Discovery in space of ethanolamine, the simplest phospholipid head group
• Impact of low-energy cosmic rays on star formation
• The far-IR spectrum of Sagittarius B2 region: Extended molecular absorption, photodissociation and photoionization
• A cluster in the making: ALMA reveals the initial conditions for high-mass cluster formation
• Thiols in the ISM: first detection of HC(O)SH and confirmation of C${}_2$H${}_5$SH
• The HNC/HCN Ratio in Star-Forming Regions
• Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk
• HCN/HNC intensity ratio: a new chemical thermometer for the molecular ISM
• Chemical modelling of complex organic molecules with peptide-like bonds in star-forming regions
• The complex chemistry of hot cores in Sagittarius B2(N): Influence of cosmic-ray ionization and thermal history
• Prebiotic precursors of the primordial RNA world in space: Detection of NH${}_2$OH
• The HCO+ emission excess in bipolar outflows
• The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone
• Interstellar formamide (NH${}_2$CHO), a key prebiotic precursor
• Distribution and mass of diffuse and dense CO gas in the Milky Way
• Exploring molecular complexity with ALMA (EMoCA): Simulations of branched carbon-chain chemistry in Sgr B2(N)
• Submillimeter ALMA Observations of the Dense Gas in the Low-Luminosity Type-1 Active Nucleus of NGC 1097
• Physical conditions in the central molecular zone inferred by H3+
• Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds
• The physical and chemical structure of Sagittarius B2. II. Continuum millimeter emission of SgrB2(M) and SgrB2(N) with ALMA
• ATLASGAL-selected massive clumps in the inner Galaxy: V. Temperature structure and evolution
• Chemistry in Cosmic-Ray Dominated Regions (CRDRs)
• ALCHEMI: an ALMA Comprehensive High-resolution Extragalactic Molecular Inventory. Survey presentation and first results from the ACA array
• HCO mapping of the Horsehead : Tracing the illuminated dense molecular cloud surfaces
• The Central 300 pc of the Galaxy probed by infrared spectra of H${}_3^{+}$ and CO: part I. Predominance of warm and diffuse gas and high H${}_2$ ionization rate
• Submillimeter-HCN Diagram for an Energy Diagnostics in the Centers of Galaxies
• On the origin of H2CO abundance enhancements in low-mass protostars
• Precursors of fatty alcohols in the ISM: Discovery of n-propanol
• Cosmic rays in molecular clouds probed by H${}_2$ rovibrational lines -- Perspectives for the James Webb Space Telescope
• On the temperature structure of the Galactic Centre cloud G0.253+0.016
• Far-Infrared Spectroscopy of the Galactic Center. Hot Molecular Gas: Shocks versus Radiation near SgrA*
• Chemical Features in the Circumnuclear Disk of the Galactic Center
• The Dense Gas Fraction in Galactic Center Clouds
• The Physical and chemical structure of Sagittarius B2 -- IV. Converging filaments in the high-mass cluster forming region Sgr B2(N)
• Nitrogen and hydrogen fractionation in high-mass star forming cores from observations of HCN and HNC
• Photodissociation Region Diagnostics Across Galactic Environments
• Search for Interstellar monohydric Thiols
• The JCMT Gould Belt Survey: Evidence for Dust Grain Evolution in Perseus Star-forming Clumps
• Tracing Interstellar Heating: An ALCHEMI Measurement of the HCN Isomers in NGC 253
• Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular clouds
• Cloud-cloud Collision in the Galactic Center 50 km s${}^{-1}$ Molecular Cloud
• Fire in the Heart: A Characterization of the High Kinetic Temperatures and Heating Sources in the Nucleus of NGC253
• Star formation in 'the Brick': ALMA reveals an active proto-cluster in the Galactic centre cloud G0.253+0.016
• Amides inventory towards the G+0.693-0.027 molecular cloud
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Ubiquitous Protostellar Outflows
• H3+ Spectroscopy and the Ionization Rate of Molecular Hydrogen in the Central Few Parsecs of the Galaxy
• From interstellar carbon monosulfide to methyl mercaptan: paths of least resistance
• Spectral imaging of the Sagittarius B2 region in multiple 7-mm molecular lines
• Warm Cores around Regions of Low-Mass Star Formation
• Bird's eye view of molecular clouds in the Milky Way: I. Column density and star formation from sub-pc to kpc scales
• SOFIA/HAWC+ Far-InfraRed Polarimetric Large Area CMZ Exploration (FIREPLACE) Survey I: General Results from the Pilot Program
• Submillimeter imaging of the Galactic Center starburst Sgr B2. Warm molecular, atomic, and ionized gas far from massive star-forming cores
• Evidence that widespread star formation may be underway in G0.253+016, "The Brick"
• Shocking Sgr B2(N1) with its own outflow: A new perspective on segregation between O- and N-bearing molecules
• Tracing shock type with chemical diagnostics: an application to L1157
• Modelling methanol and hydride formation in the JWST Ice Age era
• AzTEC Survey of the Central Molecular Zone: Data Reduction, Analysis, and Preliminary Results
• Understanding if molecular ratios can be used as diagnostics of AGN and starburst activity: The case of NGC 1068
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• CON-quest II. Spatially and spectrally resolved HCN/HCO+ line ratios in local luminous and ultraluminous infrared galaxies
• The physical and chemical structure of Sagittarius B2, VIII. Full molecular line survey of hot cores
• Interstellar Glycolaldehyde, Methyl Formate, and Acetic Acid. II. Chemical Modeling of the Bimodal Abundance Pattern in NGC 6334I
• Dual-band Unified Exploration of Three CMZ Clouds (DUET). Cloud-wide census of continuum sources showing low spectral indices
• Warm ISM in the Sgr A Complex. II. The [C/N] abundance ratio traced by [CII] 158 um and [NII] 205 um observations toward the Arched Filaments at the Galactic center
• On the effects of UV photons/X-rays on the chemistry of the Sgr B2 cloud
• ALMA observations of massive clouds in the central molecular zone: slim filaments tracing parsec-scale shocks

Cited by in corpus (1)

• One-dimensional and time-dependent modelling of complex organic molecules in protostars