redshifted extragalactic molecular lines
DESCRIPTION
Redshifted Extragalactic Molecular Lines. Mechanisms 1. Thermal 2. Masers 3. Dasars Science A. High Redshift B. Galaxy Evolution C. Star Formation/ISM D. Massive Black Holes E. Cosmology F. Physical Constants. Jeremy Darling (CASA, University of Colorado). - PowerPoint PPT PresentationTRANSCRIPT
Mechanisms 1. Thermal 2. Masers 3. Dasars
Science A. High Redshift B. Galaxy Evolution C. Star Formation/ISM D. Massive Black Holes E. Cosmology F. Physical Constants
Jeremy Darling (CASA, University of Colorado)
Redshifted Extragalactic Molecular Lines
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
Out of reach (Existence of molecules?)
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
z = 0.9 gravitational lens (e.g. Muller et al. 2006)
• high dipole moment • expect detections in submm
galaxies soon!• dense gas tracer
star formation (akin to HCN, HCO+)
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
z = 0.7, 0.9 gravitational lenses (Henkel et al. 2005, Menten et al. in prep)
• Tunneling transitions (many)• Thermometer• Constancy of me/mp
(Flambaum & Kozlov 2007)
Chengalur, deBruyn, &Chengalur, deBruyn, & Narasimha 1999Narasimha 1999
Patnaik et al. 1994Patnaik et al. 1994
Nair et al. 1993Nair et al. 1993
Ammonia (NHAmmonia (NH33): ): “Umbrella” Tunneling“Umbrella” Tunneling
Rohlfs & Wilson 1996
Ammonia (NH3) Symmetric top molecule
Electrostatic repulsion between N and H3 plane
“Umbrella” inversion possible via tunneling (for low vibration states)
Each rotation ladder has inversion splitting
Inversion transitions can be masers(first maser was NH3 24 GHz!)
Ammonia (NH3) Symmetric top molecule
Electrostatic repulsion between N and H3 plane
“Umbrella” inversion possible via tunneling (for low vibration states)
Each rotation ladder has inversion splitting
Gastrophysics Multiple inversion lines give Trot B0218+357:
z = 0.67; Trot = 35 K
PKS 1830-211: z = 0.89; up to (J,K) = (10,10) detected!
(Menten et al in prep)
(Henkel et al 2005)
Ammonia (NH3): “Umbrella” Tunneling
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
z = 0.66 maser (Barvanis & Antonucci 2005)
• 5 mJy line• Acceleration search (disks)• HSN targets• Cosmology
H2O Megamasers
• Associated with Type 2 nuclei
• Highly beamed
• NGC 4258: - VLBI proper motions of maser spots - Line accelerations
Geometric distance 7.2 0.5 Mpc (Herrnstein et al. 1999)
(H2O masers can also occur in jets and outflows)
Herrnstein et al. 1999
NGC 4258
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
No megamasers (Phillips et al 1998, Darling et al 2003)
* Menten predicts broad shallow absorption akin to Galactic Center
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
z = 0.7,0.9 gravitational lenses (Menten & Reid 1996, Menten et al. 1999)
Biggs et al 2001
Galactic H2CO
Dark Clouds: - “Anomalous” H2CO absorption (e.g. Palmer et al.
1969)
- Absorption in multiple cm lines- No radio continuum source!
Darling & Goldsmith (in prep)
Darling & Goldsmith (in prep)
Barnard 227
NGC 2264
HH22CO: CO: The DASARThe DASAR
L ightA mplification byS timulated E mission ofR adiation
Inversion: “Heating” of lines Tx >> Tkin
Pump required: Chemical, collisional, radiative
D arkness*A mplification** byS timulated A bsorption ofR adiation
Townes et al (1953)
Anti-Inversion: “Cooling” of lines Tx < TCMB
Pump required: Collisions with H2
*Not really dark.**Not a true amplification.
Galactic H2CO
Dark Clouds: - “Anomalous” H2CO absorption (e.g. Palmer et al.
1969)
- Absorption in multiple cm lines- No radio continuum source!
• Can H2CO be observed in other
galaxies?
2. Can “anomalous” H2CO absorption be
observed in galaxy-scale analogs of Dark Clouds?
Darling & Goldsmith (in prep)
Darling & Goldsmith (in prep)
Barnard 227
NGC 2264
H2CO Absorption Against the CMB
H2CO: The DASAR
The CMB is the ultimate illumination source:
• Behind everything• Everywhere• Uniform on arcsec scales
H2CO absorption against the CMB offers an unrivaled, extinction-free, mass-limited probe of dense (star-forming) molecular gas, independent of redshift!
Extragalactic H2CO
Emission in (U)LIRGs (OH Megamasers)
Arp 220 III Zw 35
Absorption in starbursts (OH absorbers)
NGC 520NGC 660
Henkel & Darling (in prep)
Baan, Guesten, & Haschick (1986)
Extragalactic HExtragalactic H22CO CO
Emission in (U)LIRGs (OH Megamasers)
Arp 220 III Zw 35
Absorption in starbursts (OH absorbers)
NGC 520NGC 660
Filho, Barthel, & Ho (2002)
NGC 660, 8.4 GHz
Henkel & Darling (in prep)
Extragalactic H2CO So far…• All OHMs show 6 cm emission in H2CO• All OH absorbers show 6 cm absorption
H2CO 6 cm line flip at
n(H2) ~ 105.6 cm-3
A critical density threshold for OH megamasers?
(there must also be a density upper limit where inversion is quenched… n(H2) ~ 106 cm-3)
H2CO Survey of Local Star-Forming Galaxies
(Mangum, Darling, Menten, & Henkel, 2007)
M 82
Arp 220
6 cm
6 cm
2 cm 2 cm
So far…• All OHMs show 6 cm emission in H2CO• All OH absorbers show 6 cm absorption
H2CO 6 cm line flip at
n(H2) ~ 105.6 cm-3
A critical density threshold for OH megamasers?
(there is also an upper density where 2 cm line flips… n(H2) ~ 105.8 cm-3)
(Mangum et al. 2007)
6 cm
2 cm
OHMs
(kilomaser)
Extragalactic H2CO
• H2CO dasar effect
spans 3 orders of magnitude in density
• cm line ratio is sensitive to n(H2)
Darling & Zeiger
Extragalactic H2CO
• H2CO dasar effect
is insensitive to TCMB
• The effect likely becomes easier to detect with increasing redshift!
Darling & Zeiger
Extragalactic H2CO
Darling & WiklindBiggs et al 2001
Extragalactic H2CO
Maser Emission in (U)LIRGs (OH Megamasers)
Arp 220 III Zw 35
Absorption in starbursts (OH absorbers)
NGC 520NGC 660
Absorption in dense cloudsB0218+357PKS 1830-211
Redshifted Molecular Lines
Linez when
= 10 GHz
CO (1-0) 10.5
HCN (1-0) 7.9
HCO+ (1-0) 7.9
CS (1-0) 3.9
SiO (1-0) 3.3
NH3 (24 GHz) 1.4
H2O (22 GHz) 1.2
H2CO (211-212) 0.45
HC3N (1-0) Any
CH3OH (6.7 GHz) Any
H2CO (110-111) Any
OH (1.8, 4.7, 6.0 GHz) Any
z = 0.26 megamaser z = 0.9 gravitational lens
IRAS 02524+2046 z = 0.18
PKS 1830-211
z = 0.89HI
OH
Merging Galaxies:
OH Megamasers: OH Megamasers: Tracers of Major Mergers, Star Formation, and Massive Black Holes
• OH FIR and favors dusty environments• OHMs seem to indicate massive black holes (small sample)• OHMs seem to favor a specific stage of merging, star formation• Sampling a specific stage of merging BH binary formation rate long-period GW background• There are many approaches to these problems; no single method will be a panacea.
OH Megamasers: OH Megamasers: Tracers of Major Mergers, Star Formation, and Massive Black Holes
• OH FIR and favors dusty environments• OHMs seem to indicate massive black holes (small sample)• OHMs seem to favor a specific stage of merging, star formation• Sampling a specific stage of merging BH binary formation rate long-period GW background• There are many approaches to these problems; no single method will be a panacea.
Begelman, Blandford & Rees 1980
OHMs
GWs
(CSOs?)
OH Megamasers in HI Surveys
Briggs (1988)
20 mJy
5 mJy
1 mJy
0.2 mJy
OH Megamasers: Power-law LF Increasing Merger RateIncreasing Star Formation
Briggs (1998): The deeper the HI survey, the more confusion with OH megamasers
At z ~ 0.1 the OH line > HI line
(but remains rare)
At z ~ 1 there is ~ 1 OHM per deg2
OH Megamaser Surveys: High(er) Redshift
Barriers– RFI– Receivers– Rarity
Boons– Half of OH megamasers are QSO-like– Current sensitivity is adequate for z ~ 1– More merging in past
Detecting OHMegamasers atHigh Redshift
Submm Galaxies
PKS 1413+135: OH and HI Absorption
Conjugate OH satellite lines:1612, 1720 MHz(see also Kanekar et al. 2004)
Systematic offset from HI
Is the offset physical?
How to assess offsets?
13 km s-1
Variability in OH Megamasers: Super-VLBI Resolution
Multiple independent variable features with different timescales:
Segregates sizescales
May segregate positions
Offers sub- milliarcsecond resolution
Sensitivity is key
02524+2046
Observations:
• Day-to-day (and intraday) variation
• Multiple narrow variable components
• 1665 MHz line varies, often (but not always) with 1667
• Components often (but not always) correspond to peaks
Darling (in prep)
02524+2046
Observations: • Unprecedented matching between 1665 and 1667 MHz lines in average and variable fits, including flaring lines
• Variation envelope shows proportional 1667:1665 modulation of ~20% (~30% expected for point source)
• Size scales < 1 pc (0.3 milliarcsec)
• Tb > 81011 K (!)
• (What is line separation in sky?)
Darling (in prep)
Variability Studies: A Super-VLBI Single Dish Telescope
• Variability studies can segregate size scales and on-sky projections of OH megamaser components with super-VLBI resolution (~pc at z = 0.2).
• Roughly half of luminous OMHs at z > 0.1 are variable/compact.
• We have identified compact 1665 MHz emission coincident with compact 1667 MHz lines. • Observed phenomena are consistent with strong refractive ISS (and detailed tests are possible)
• ISS predictions are consistent with VLBI observations
• Long-term monitoring can identify small accelerations
CharacterizingVariability
• 10% modulation
• 4.5 day timescale
Assuming ISS
Variable features: < 1.2 parsec
Quiescent features: > 4 parsec
CharacterizingVariability
• 10% modulation
• 4.5 day timescale
Assuming ISS
Variable features: < 1.2 parsec
Quiescent features: > 4 parsec
Robishaw, Heiles, & Quataert
z = 0.217
Magnetic Fields in OH Megamasers
Robishaw, Heiles, & Quataert have detected Zeeman splitting in multiple OH megamaser galaxies!
Prediction:
Zeeman splitting will also be observable in OH conjugate lines and OH in molecular absorption systems (detectable at arbitrary redshift).
Discussion Questions: High FrequencyWhat can be done to improve 5-10 GHz sensitivity?
– Has double position switching been evaluated at high frequency?– What bandwidths can be correlated?– How good are baselines across 100 MHz? 1 GHz?
• The H2CO “densitometer” offers tremendous promise• H2O surveys and studies (cosmology)• NH3 tunneling lines• High redshift CS
How high in frequency can Arecibo still work with the HSA?– What is the impact of strong continuum on Arecibo within the HSA? – Any hope for observations of molecular absorption systems?
Is there an irreducible noise floor?– How low can we go?– Can we have certainty when observing weak lines?
Discussion Questions: Low FrequencyIs 800 MHz feasible?
– OH (megamasers, conjugate lines, absorption) at z~1 – HI absorption (intrinsic, gravitational lenses, damped Ly systems)– Changing physical constants, peak of star formation, merging, BH growth– Interferometer with GBT, possibly WSRT
Are polarization observations possible with double position switching?
– B fields in single clouds at high z via OH conjugate lines, absorption
Is there an irreducible noise floor in L-band or below?– (How low can we go?)