A survey of the Galactic center region in HCO+, H13CO+, and SiO

Riquelme, D.; Bronfman, L.; Mauersberger, R.; May, J.; Wilson, Thomas L.

doi:10.1051/0004-6361/200913359

Cited by 42 publications

(58 citation statements)

References 54 publications

(103 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been observed previously by several authors (Bitran et al 1997;Fukui et al 2006;Sawada et al 2001;Lee & Lee 2003;Riquelme et al 2010b); its main velocity component is at 98 km s −1 (from the HCO + data from Riquelme et al 2010b), and a large velocity width in all the species is observed in this and previous works, which indicates that this source indeed belongs to the GC region. …”

Section: Single Temperature Regime In the Loop Regionsupporting

confidence: 83%

“…The beam width of the telescope at 23.7 GHz is 42.2 . The spectra were observed in position-switching mode, with the emission-free reference positions from Riquelme et al (2010b), which were checked in the first setup, where the most intense lines are detected. Each position was observed for 12 min in the first setup, 24 min in the second setup, and 32 min in the third setup.…”

Section: Effelsberg Observationsmentioning

confidence: 99%

“…Spectra toward selected positions in the GC in the metastable inversion transitions from (1, 1) to (6, 6) of NH 3 . The positions are indicated in the HCO + integrated intensity map from Riquelme et al (2010b). The GMLs found by Fukui et al (2006) are indicated in blue.…”

Section: Effelsberg Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Kinetic temperatures toward X1/X2 orbit interceptions regions and giant molecular loops in the Galactic center region

Riquelme

Amo-Baladrón

Martı́n-Pintado

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

Context. It is well known that the kinetic temperatures, T kin , of the molecular clouds in the Galactic center region are higher than in typical disk clouds. However, the T kin of the molecular complexes found at higher latitudes towards the giant molecular loops in the central region of the Galaxy is so far unknown. The gas of these high-latitude molecular clouds (hereafter referred to as "halo clouds") is located in a region where the gas in the disk may interact with the gas in the halo in the Galactic center region. Aims. To derive T kin in the molecular clouds at high latitude and understand the physical process responsible for the heating of the molecular gas both in the central molecular zone (the concentration of molecular gas in the inner ∼500 pc) and in the giant molecular loops. Methods. We measured the metastable inversion transitions of NH 3 from (J, K) = (1, 1) to (6, 6) toward six positions selected throughout the Galactic central disk and halo. We used rotational diagrams and large velocity gradient (LVG) modeling to estimate the kinetic temperatures toward all the sources. We also observed other molecules like SiO, HNCO, CS, C 34 S, C 18 O, and 13 CO, to derive the densities and to trace different physical processes (shocks, photodissociation, dense gas) expected to dominate the heating of the molecular gas. Results. We derive for the first time T kin of the high-latitude clouds interacting with the disk in the Galactic center region. We find high rotational temperatures in all the observed positions. We derive two kinetic temperature components (∼150 K and ∼40 K) for the positions in the central molecular zone, and only the warm kinetic temperature component for the clouds toward the giant molecular loops. The fractional abundances derived from the different molecules suggest that shocks provide the main heating mechanism throughout the Galactic center, also at high latitudes.

show abstract

Section: Single Temperature Regime In the Loop Regionsupporting

confidence: 83%

Section: Effelsberg Observationsmentioning

confidence: 99%

See 1 more Smart Citation

Kinetic temperatures toward X1/X2 orbit interceptions regions and giant molecular loops in the Galactic center region

Riquelme

Amo-Baladrón

Martı́n-Pintado

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…In fact, Fukui et al (2006) discovered two large molecular loops, loop 1 and loop 2, at a radius of 700-pc from the center, which are triggered by magnetic buoyancy (Parker instability;Parker 1966); while the main focus in Parker (1966) was aimed at the Galactic disk, he already suggested that the magnetic activity might become even more important in the central few 100 pc. Subsequently, Fujishita et al (2009);Torii et al (2010a,b); Riquelme et al (2010); Kudo et al (2011) presented analyses of more detailed observational properties of these molecular loops, and it was shown that the molecular loops are also well reproduced by magneto-hydrodynamical (MHD, hereafter) simulations (Shibata & Matsumoto 1991;Machida et al 2009;Takahashi et al 2009). …”

Section: E-mail: Stakeru@nagoya-ujp (Tks)mentioning

confidence: 99%

Stochastic non-circular motion and outflows driven by magnetic activity in the Galactic bulge region

Suzuki

Fukui

Torii

et al. 2015

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

By performing a global magneto-hydrodynamical simulation for the Milky Way with an axisymmetric gravitational potential, we propose that spatially dependent amplification of magnetic fields possibly explains the observed noncircular motion of the gas in the Galactic center region. The radial distribution of the rotation frequency in the bulge region is not monotonic in general. The amplification of the magnetic field is enhanced in regions with stronger differential rotation, because magnetorotational instability and field-line stretching are more effective. The strength of the amplified magnetic field reaches > ∼ 0.5 mG, and radial flows of the gas are excited by the inhomogeneous transport of angular momentum through turbulent magnetic field that is amplified in a spatially dependent manner. In addition, the magnetic pressuregradient force also drives radial flows in a similar manner. As a result, the simulated position-velocity diagram exhibits a time-dependent asymmetric parallelogram-shape owing to the intermittency of the magnetic turbulence; the present model provides a viable alternative to the bar-potential-driven model for the parallelogram-shape of the central molecular zone. This is a natural extension into the central few 100 pc of the magnetic activity, which is observed as molecular loops at radii from a few 100 pc to 1 kpc. Furthermore, the time-averaged net gas flow is directed outward, whereas the flows are highly time-dependent, which we discuss from a viewpoint of the outflow from the bulge.

show abstract

“…Three of them are located at the foot points and two at the top of the loops. Two positions are in the disk toward the locations of the expected interactions between the X1 and X2 orbits (Disks X1 and X2 in Tables 2, 3 The positions at the foot points of the GMLs were selected from the intensity peaks of the SiO maps of Riquelme et al (2010) and from previous results from higher angular resolution mapping with the Mopra-22 m telescope (Riquelme et al, in prep.). The Fukui et al (2006) maps of the GMLs were used to select the position at the top of the loop.…”

Section: Observationsmentioning

confidence: 99%

Tracing gas accretion in the Galactic center using isotopic ratios

Riquelme

Amo-Baladrón

Martı́n-Pintado

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We study the 12 C/ 13 C isotopic ratio in the disk of the central molecular zone and in the halo to trace gas accretion toward the Galactic center region in the Milky Way. Methods. Using the IRAM 30m telescope, we observed the J = 1−0 rotational transition of HCO + , HCN, HNC, and their 13 C isotopic substitutions in order to measure the 12 C/ 13 C isotopic ratio. We observed 9 positions selected throughout the Galactic center region, including clouds at high latitude, locations where the X1 and X2 orbits associated with the barred potential are expected to intersect, and typical Galactic center molecular clouds. Results. We find a systematically higher 12 C/ 13 C isotopic ratio (>40) toward the halo and the X1 orbits than for the Galactic center molecular clouds (20-25). Our results point to molecular gas that has undergone a different degree of nuclear processing than observed in the gas towards the inner Galactic center region. Conclusions. The high isotopic ratios are consistent with the accretion of the gas from the halo and from the outskirts of the Galactic disk.

show abstract

A survey of the Galactic center region in HCO⁺, H¹³CO⁺, and SiO

Cited by 42 publications

References 54 publications

Kinetic temperatures toward X1/X2 orbit interceptions regions and giant molecular loops in the Galactic center region

Kinetic temperatures toward X1/X2 orbit interceptions regions and giant molecular loops in the Galactic center region

Stochastic non-circular motion and outflows driven by magnetic activity in the Galactic bulge region

Tracing gas accretion in the Galactic center using isotopic ratios

Contact Info

Product

Resources

About