Recent star formation in the inner Galactic Bulge seen by ISOGAL II -- The Central Molecular Zone

Abstract

We present 5--38 $\mu$m spectroscopic observations of a sample of 68 ISOGAL sources with unknown natures, taken with the Spitzer Infrared Spectrograph. Based on the characteristics and the slope of their spectra we classified the sources as young or late-type evolved objects. These sources were selected to test selection criteria based on the ISOGAL [7]--[15] color and the spatial extent parameter ${\sigma }_{15}$. We revised these criteria until they reliably distinguished between young and late-type evolved objects and then applied them to all ISOGAL sources in the central molecular zone (CMZ), resulting in the selection of 485 sources believed to be young. Furthermore, we added 656 Midcourse Space Experiment (MSX) sources to the CMZ sample that fulfilled $F_{\mathrm{E}}/F_{\mathrm{D}}>2$ with $F\mathrm{D}$ and $F_{\mathrm{E}}$ being the flux densities in the D (15 $\mu$m) and E (21 $\mu$m) bands. After obtaining $\frac{L_{\mathrm{bol}}}{F_{15}}$ conversion factors, we calculated the bolometric luminosity, $L_{\mathrm{bol}}$, values for the CMZ sample and subsequently the masses of the sources. Applying a Kroupa initial mass function, we derived the total mass in young objects that has been formed over the last 1 Myr, resulting in an average star formation rate of 0.08 solar masses per year for the CMZ.

Accepted for publication in A&A, 20 pages, 10 figures, 3 tables

References in corpus (4)

• Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
• Interstellar Extinction Law toward the Galactic Center II: V, J, H, and Ks Bands
• Wild at Heart:-The Particle Astrophysics of the Galactic Centre
• Interstellar Extinction and Long-Period Variables in the Galactic Center

Cited by in corpus (65)

• Star Formation in the Milky Way and Nearby Galaxies
• Star Clusters Across Cosmic Time
• The Fermi Galactic Center GeV Excess and Implications for Dark Matter
• ATLASGAL --- properties of a complete sample of Galactic clumps
• Variations in the Galactic star formation rate and density thresholds for star formation
• What controls star formation in the central 500 pc of the Galaxy?
• ATLASGAL --- towards a complete sample of massive star forming clumps
• Star formation rates and efficiencies in the Galactic Centre
• ATLASGAL --- Environments of 6.7\,GHz methanol masers
• ATLASGAL --- properties of compact HII regions and their natal clumps
• The Galactic Center Molecular Cloud Survey. I. A Steep Linewidth-Size Relation & Suppression of Star Formation
• Simulations of the Milky Way's central molecular zone -- I. Gas dynamics
• ATLASGAL-selected massive clumps in the inner Galaxy III. Dust Continuum Characterization of an Evolutionary Sample
• Simulations of the Milky Way's central molecular zone -- II. Star formation
• Mass inflow rate into the Central Molecular Zone: observational determination and evidence of episodic accretion
• Non-Thermal Insights on Mass and Energy Flows Through the Galactic Centre and into the Fermi Bubbles
• Fermi Bubbles in the Milky Way: the closest AGN feedback laboratory courtesy of Sgr A*?
• ATLASGAL -- Evolutionary trends in high-mass star formation
• The Life Cycle of the Central Molecular Zone. I: Inflow, Star Formation, and Winds
• Strong Evidence that the Galactic Bulge is Shining in Gamma Rays
• Effects of Gas on Formation and Evolution of Stellar Bars and Nuclear Rings in Disk Galaxies
• The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo
• The Fermi Bubbles as Starburst Wind Termination Shocks
• The Star Formation Rate of the Milky Way as seen by Herschel
• Multi-wavelength features of Fermi Bubbles as signatures of a Galactic wind
• CMZoom: Survey Overview and First Data Release
• Star Formation Rates of Massive Molecular Clouds in the Central Molecular Zone
• Infrared H3+ and CO Studies of the Galactic Core: GCIRS 3 and GCIRS 1W
• A Census of Early Phase High-Mass Star Formation in the Central Molecular Zone
• The Galactic Center Molecular Cloud Survey. II. A Lack of Dense Gas & Cloud Evolution along Galactic Center Orbits
• Improved Cosmic-Ray Injection Models and the Galactic Center Gamma-Ray Excess
• Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular clouds
• On the physical mechanisms governing the cloud lifecycle in the Central Molecular Zone of the Milky Way
• Temperature structures in Galactic Center clouds - Direct evidence for gas heating via turbulence
• Hard and bright gamma-ray emission at the base of the Fermi bubbles
• Possible connection between the asymmetry of North Polar Spur and Loop I with Fermi Bubbles
• Star Formation in Nuclear Rings with the TIGRESS Framework
• Chemical evolution of the Galactic Center
• CMZoom II: Catalog of Compact Submillimeter Dust Continuum Sources in the Milky Way's Central Molecular Zone
• Constraining the population of isolated massive stars within the Central Molecular Zone
• Spitzer Infrared Spectrograph Observations of the Galactic Center: Quantifying the Extreme Ultraviolet/so ft X-ray fluxes
• SOFIA/FORCAST Galactic Center Legacy Survey: Overview
• A global view on star formation: The GLOSTAR Galactic plane survey IV. Radio continuum detections of young stellar objects in the Galactic Centre region
• Hydrodynamic simulations of the central molecular zone with realistic Galactic potential
• Exploring the Impact of Galactic Interactions and Mergers on the Central Star Formation of APEX/EDGE-CALIFA Galaxies
• The CARMA 3mm Survey of the Inner $0.7^{\circ }\times 0.4^{\circ }$ of the Central Molecular Zone
• Near-infrared spectroscopic observations of massive young stellar object candidates in the Central Molecular Zone
• High Velocity Compact Clouds in the Sagittarius C Region
• Evidence of a Cloud-Cloud Collision from Overshooting Gas in the Galactic Center
• Fiery Cores: Bursty and Smooth Star Formation Distributions across Galaxy Centers in Cosmological Zoom-in Simulations
• Virial Clumps in Central Molecular Zone Clouds
• A new distance to the Brick, the dense molecular cloud G0.253+0.016
• Massive Young Stellar Objects in the Galactic Center. II. Seeing Through the Ice-rich Envelopes
• Living on the edge of the Central Molecular Zone: G1.3 is the more likely candidate for gas accretion into the CMZ
• Probing the Global Dust Properties and Cluster Formation Potential of the Giant Molecular Cloud G148.24+00.41
• New Look at the Molecular Superbubble Candidate in the Galactic Center
• A Brief Update on the CMZoom Survey
• Disc-halo gas outflows driven by stellar clusters as seen in multiwavelength tracers
• Towards a multi-scale understanding of the gas-star formation cycle in the Central Molecular Zone
• WISE Green Objects (WGOs): the massive star candidates in the whole Galactic Plane ($\mid b\mid <2^{\circ }$)
• Discovery of a giant molecular loop in the central region of NGC 253
• Evidence for powerful winds and the associated reverse shock as the origin of the Fermi bubbles
• ArH+ and H2O+ absorption towards luminous galaxies
• Mass Segregation in the CMZoom Survey
• Modelling the non-equilibrium chemistry of the Milky Way's cold nuclear wind