J/A+A/649/A32 Sgr B2 Herschel/SPIRE-FTS and IRAM 30m maps (Santa-Maria+, 2021)
Submillimeter imaging of the Galactic Center starburst Sgr B2.
Warm molecular, atomic, and ionized gas far from massive star-forming cores.
Santa-Maria M.G., Goicoechea J.R., Etxaluze M., Cernicharo J., Cuadrado S.
<Astron. Astrophys. 649, A32 (2021)>
=2021A&A...649A..32S 2021A&A...649A..32S (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds
Keywords: ISM: clouds - photon-dominated region - infrared: ISM -
Galaxy: center - ISM: molecules - cosmic rays
Abstract:
We present 168 arcmin2 spectral images of the Sgr B2 complex taken
with Herschel/SPIRE-FTS. We detect ubiquitous emission from CO (up to
J=12-11), H2O 21,1-20,2, [CI]492, 809GHz, and [NII] 205um lines.
We also present maps of the SiO, N2H+, HCN, and HCO+ emission
obtained with the IRAM30m telescope. The cloud environment dominates
the emitted FIR (80%), H2O 752GHz (60%) mid-J CO (91%), and [CI]
(93%) luminosity. The region shows very extended [NII] emission
(spatially correlated with the 24 and 70um dust emission). The
observed FIR luminosities imply G0∼103. The extended [CI] emission
arises from a pervasive component of neutral gas with nH∼103cm-3^.
The high ionization rates, produced by enhanced cosmic-ray (CR)
fluxes, drive the gas heating to Tk∼40-60K. The mid-J CO emission
arises from a similarly extended but more pressurized gas component
(Pth/k∼107K/cm3). Specific regions of enhanced SiO emission and
high CO-to-FIR intensity ratios (>10-3) show mid-J CO emission
compatible with shock models. A major difference compared to more
quiescent star-forming clouds in the disk of our Galaxy is the
extended nature of the SiO and N2H+ emission in Sgr B2. This can be
explained by the presence of cloud-scale shocks, induced by
cloud-cloud collisions and stellar feedback, and the much higher CR
ionization rate (>10-15s-1) leading to overabundant H3+ and
N2H+. Hence, Sgr B2 hosts a more extreme environment than
star-forming regions in the disk of the Galaxy. As a usual template
for extra- galactic comparisons, Sgr B2 shows more similarities to
ultra luminous infrared galaxies such as Arp 220, including a
"deficit" in the [CI]/FIR and [NII]/FIR intensity ratios, than to pure
starburst galaxies such as M82. However, it is the extended cloud
environment, rather than the cores, that serves as a useful template
when telescopes do not resolve such extended regions in galaxies.
Description:
The ASCII files contain the following line surface brightness images:
- CO (10-9), [CI] 3P2-3P1, H_2O (211-20,2), and [NII] 3P1-3P0 shown
in Fig. 2.
- CO (4-3), CO (5-4), CO (6-5), CO (7-6), CO (8-7), and CO (9-8) shown
in Fig. A.1.
- CO (11-10), CO (12-11), 13CO (5-4), 13CO (6-5), 13CO (7-6), and [CI]
3P1-3P0 shown in Fig. A.2.
The intensity scale is in units of W/m2/sr.
- N2H+ (1-0), SiO (2-1), HCO+ (1-0), and HCN (1-0) shown in Fig. 4
The intensity scale is in units of K.km/s.
Objects:
---------------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------------
17 47 20.4 -28 23 07 Sgr B2 = NAME Sgr B2
17 47 20.5 -28 23 06 Sgr B2(M) = NAME Sgr B2 Main
17 47 20.2 -28 22 21 Sgr B2(N) = NAME Sgr B2 (North)
17 47 20.4 -28 23 45.1 Sgr B2(S) = NAME Sgr B2 (South)
17 47 41.5 -28 26 23 G0.66-0.13 = GAL 000.66-00.13
17 47 38.5 -28 19 06 G0.76-0.06 = GAL 000.76-00.06
17 47 -28.4 G0.6-0.0 = GAL 000.6-00.0
---------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 106 20 List of line surface brightness images
fig2/* . 5 SPIRE-FTS integrated line intensity maps
presented in Fig. 2
fig4/* . 4 IRAM 30m telescope total integrated line
intensity maps presented in Fig. 4
figa1/* . 6 SPIRE-FTS surface brightness maps
presented in Fig. A1
figa2/* . 5 SPIRE-FTS surface brightness maps
presented in Fig. A2
--------------------------------------------------------------------------------
See also:
J/A+A/482/179 : Interferometric study of SgrB2(N) (Belloche+, 2008)
J/A+A/559/A47 : Sgr B2(N) and Sgr B2(M) IRAM 30m line survey (Belloche+, 2013)
J/A+A/604/A6 : SgrB2 ALMA continuum and spectral index (Sanchez-Monge+, 2017)
J/A+A/610/A10 : Sgr B2 los molecular absorption line spectra (Corby+, 2018)
J/A+A/633/A120 : SgrB2(M) 13CCC and C13CC spectra (Giesen +, 2020)
J/A+A/641/A160 : Hot aminoacetonitrile in Sgr B2 (Melosso+, 2020)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg Right Ascension of center (J2000)
11- 17 F7.3 deg DEdeg Declination of center (J2000)
19- 22 I4 Kibyte size Size of ASCII file
24- 62 A39 --- FileName Name of ASCII file
65-106 A42 --- Title Title of the ASCII file
--------------------------------------------------------------------------------
Byte-by-byte Description of file (#): fig2/* figa1/ figa2/**
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
3- 12 E10.4 deg RAdeg [] Right ascension (J2000)
15- 24 E10.4 deg DEdeg [] Declination (J2000)
27- 36 E10.4 W/m2/sr Int Intensity
--------------------------------------------------------------------------------
Byte-by-byte Description of file (# headlines): fig4/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 deg RAdeg [] Right ascension (J2000)
10- 17 F8.3 deg DEdeg [] Declination (J2000)
19- 31 F13.9 K.km/s Int Intensity
--------------------------------------------------------------------------------
Acknowledgements:
Miriam G. Santa-Maria, miriam.g.sm(at)csic.es
Javier R. Goicoechea, javier.r.goicoechea(at)csic.es
References:
Zhang et al., 2015ApJ...815..132Z 2015ApJ...815..132Z, Hard X-ray morphological and spectral
studies of the Galactic Center molecular cloud Sgr B2: constraining past
Sgr A* flaring activity.
(End) Miriam Santa-Maria [CSIC, Spain], Patricia Vannier [CDS] 23-Apr-2021