The Science Case for Band 1 James Di Francesco Herzberg Institute of Astrophysics Victoria, BC,...

The Science Case for Band 1James Di FrancescoHerzberg Institute of AstrophysicsVictoria, BC, Canada

Band 1 - what Band 1 - what is it?is it?

Band 1 - what Band 1 - what is it?is it?

• one of the 10 original bands intended for one of the 10 original bands intended for ALMAALMA• specs: 31.3 - 45 GHz,specs: 31.3 - 45 GHz, T TRxRx ~ 17-28 K, USB, ~ 17-28 K, USB, HEMT designHEMT design• removed in early 2000’s during to save removed in early 2000’s during to save construction costsconstruction costs

Science Case for Band 1


1 2

4

5

810

9 mm

350 m

Can Band 1 be Can Band 1 be restored?restored?

Can Band 1 be Can Band 1 be restored?restored?

• ALMA post-ALMA post-construction construction “development” plan, “development” plan, involves community, new involves community, new directionsdirections

• workshop held in workshop held in Victoria, BC on 8-10 Victoria, BC on 8-10 October 2008 to revisit October 2008 to revisit the Band 1 science casethe Band 1 science case

• Band 1Band 1 enriches enriches ALMA ALMA science at other bands, science at other bands, extendsextends ALMA science to ALMA science to new regimesnew regimes



1

1

ALMA receiver optics

32

107

4

69

85

CO from High-Z galaxiesCO from High-Z galaxiesCO from High-Z galaxiesCO from High-Z galaxies

• molecular gas now molecular gas now detected at detected at ZZ ~ 6, eg., ~ 6, eg., SDSS J1148+5251 at VLA, SDSS J1148+5251 at VLA, IRAM (Walter et al. IRAM (Walter et al. 2003)2003)

• CO data reveal CO data reveal excitation & kinematics excitation & kinematics of early star and of early star and galaxy formationgalaxy formation

• ALMA Band 1 receivers ALMA Band 1 receivers could detect CO (2-1) could detect CO (2-1) from galaxies at from galaxies at ZZ = 4- = 4-6 and CO (3-2) from 6 and CO (3-2) from galaxies at galaxies at ZZ = 6-10 = 6-10



J1148 CO (3-2)

1”

Walter et al. 2004

VLA


• molecular gas now molecular gas now detected at detected at ZZ ~ 6, eg., ~ 6, eg., SDSS J1148+5251 at VLA, SDSS J1148+5251 at VLA, IRAM (Walter et al. IRAM (Walter et al. 2003)2003)

• CO data reveal CO data reveal excitation & kinematics excitation & kinematics of early star and of early star and galaxy formationgalaxy formation

• ALMA Band 1 receivers ALMA Band 1 receivers could detect CO (2-1) could detect CO (2-1) from galaxies at from galaxies at ZZ = 4- = 4-6 and CO (3-2) from 6 and CO (3-2) from galaxies at galaxies at ZZ = 6-10 = 6-10



Sunyaev-Zel’dovich Sunyaev-Zel’dovich EffectEffect




• hot electrons in galaxy clusters scatter hot electrons in galaxy clusters scatter CMB emission to higher energies, make “holes” CMB emission to higher energies, make “holes” in CMB at some frequenciesin CMB at some frequencies• SZE dependent on pressure, independent of SZE dependent on pressure, independent of redshift, used to derive redshift, used to derive HHoo, baryon fraction, , baryon fraction, cluster morphologycluster morphology





• ALMA Band 1 will reveal ALMA Band 1 will reveal substructuresubstructure in in clusters, eg., shocks from recent mergers, clusters, eg., shocks from recent mergers, eliminate systematics from low-res obs.eliminate systematics from low-res obs.• could also begin to probe SZE in could also begin to probe SZE in individual individual galaxiesgalaxies (giant Es), explore AGN/SMBH feedback (giant Es), explore AGN/SMBH feedback and galaxy density profiles (DM)and galaxy density profiles (DM)

~3 ~3 K rms in K rms in 22”22”

~15 ~15 K rms in K rms in 10”10”

John Carlstrom

John Carlstrom

Dust in Protoplanetary Dust in Protoplanetary DisksDisks




• protostars can be protostars can be surrounded by accretion surrounded by accretion disks of gas and dust, disks of gas and dust, the birthplaces of the birthplaces of planetsplanets

• cool disk dust emits cool disk dust emits thermal radiation in thermal radiation in proportion to its proportion to its opacity, opacity,

• opacity is related to opacity is related to grain size distribution grain size distribution and compositionand composition

Adams et al. 1988, following Draine & Lee 1984Adams et al. 1988, following Draine & Lee 1984

~2

30 mISM

T. GreeneT. Greene





• protostars can be protostars can be surrounded by accretion surrounded by accretion disks of gas and dust, disks of gas and dust, the birthplaces of the birthplaces of planetsplanets

• cool disk dust emits cool disk dust emits thermal radiation in thermal radiation in proportion to its proportion to its opacity, opacity,

• opacity is related to opacity is related to grain size distribution grain size distribution and compositionand composition

Adams et al. 1988, following Draine & Lee 1984Adams et al. 1988, following Draine & Lee 1984

~2

30 mISM





• spectral energy distributions of young spectral energy distributions of young stars can reveal grain growth from ISM dust, stars can reveal grain growth from ISM dust, towards planet formation?towards planet formation?• since Band 1 samples longer wavelengths, since Band 1 samples longer wavelengths, it samples larger grains and provides longer it samples larger grains and provides longer lever arm to SEDs (departures?)lever arm to SEDs (departures?)• free-free emission may be a problem, need free-free emission may be a problem, need lower lower too too

=0.70.1

Calvet et al. 2002

Radio SupernovaeRadio SupernovaeRadio SupernovaeRadio Supernovae



• SNe radio SNe radio lightcurveslightcurves reveal density profiles reveal density profiles of ejecta and of ejecta and circumstellar medium circumstellar medium (CSM)(CSM)• SNe SNe imagesimages show show structure and size of structure and size of shell, deceleration, shell, deceleration, geometric distance from geometric distance from expanding shock front expanding shock front method method • Can also search for Can also search for stellar remnant of stellar remnant of explosion, ie., the explosion, ie., the pulsar wind nebula pulsar wind nebula (PWN)(PWN)

SN 1987A (epoch 2006.9)SN 1987A (epoch 2006.9)

ATCA at 9 GHz (0.4” FWHM)

Gaensler et al. (2007)




• SNe radio SNe radio lightcurveslightcurves reveal density profiles reveal density profiles of ejecta and of ejecta and circumstellar medium circumstellar medium (CSM)(CSM)• SNe SNe imagesimages show show structure and size of structure and size of shell, deceleration, shell, deceleration, geometric distance from geometric distance from expanding shock front expanding shock front method method • Can also search for Can also search for stellar remnant of stellar remnant of explosion, ie., the explosion, ie., the pulsar wind nebula pulsar wind nebula (PWN)(PWN)

SN 1986JSN 1986J

Red: 5 GHz VLBIBlue/White: 15 GHz VLBI

Bietenholz, Bartel & Rupen (2004)




• Band 1: radio SNe Band 1: radio SNe lightcurves, study lightcurves, study galactic “factories,” galactic “factories,” rates, search for rates, search for stellar remnantsstellar remnants• SN1987A: 0.12” FWHM, SN1987A: 0.12” FWHM, expect 300 beams across expect 300 beams across shell in 2014, get 100:1 shell in 2014, get 100:1 dynamic range in 12 hdynamic range in 12 h• VLBI at 43 GHz with VLBI at 43 GHz with ALMA and VLA/VLBA/GBT, ALMA and VLA/VLBA/GBT, good good uvuv coverage for coverage for low-dec sources, Sgr A*, low-dec sources, Sgr A*, lots of AGN, SNe? lots of AGN, SNe?

McDonald et al. McDonald et al. (2001)(2001)

SN remnants in SN remnants in M82M82




• Band 1: radio SNe Band 1: radio SNe lightcurves, study lightcurves, study galactic “factories,” galactic “factories,” rates, search for rates, search for stellar remnantsstellar remnants• SN1987A: 0.12” FWHM, SN1987A: 0.12” FWHM, expect 300 beams across expect 300 beams across shell in 2014, get 100:1 shell in 2014, get 100:1 dynamic range in 12 hdynamic range in 12 h• VLBI at 43 GHz with VLBI at 43 GHz with ALMA and VLA/VLBA/GBT, ALMA and VLA/VLBA/GBT, good good uvuv coverage for coverage for low-dec sources, Sgr A*, low-dec sources, Sgr A*, lots of AGN, SNe? lots of AGN, SNe?

VLBI network with ALMAVLBI network with ALMA

……and more!and more!……and more!and more!



• debris disks debris disks • chemistry of heavy organic species, chemistry of heavy organic species, carbon-chains, anions carbon-chains, anions • free-free emission from jets/outflowsfree-free emission from jets/outflows• measuring B-field using Zeeman effect measuring B-field using Zeeman effect (CCS)(CCS)• spinning dust grainsspinning dust grains• dust chemistry in AGB envelopesdust chemistry in AGB envelopes• masers masers We are working on a detailed Band 1 We are working on a detailed Band 1 Science Case document to distribute Science Case document to distribute online to the community.online to the community.

ALMA band 1 vs. EVLA Q-ALMA band 1 vs. EVLA Q-bandband




EVLAEVLA ALMAALMA





• ALMA and EVLA have, to first order, the ALMA and EVLA have, to first order, the same sensitivity at 31-45 GHz: same sensitivity at 31-45 GHz: 1 1 rms ~ 1 rms ~ 1 Jy in 12 hoursJy in 12 hours• ALMA advantages ALMA advantages : few weather : few weather restrictions, greater no. of baselines restrictions, greater no. of baselines (imaging quality), wider FOV (SZE/debris (imaging quality), wider FOV (SZE/debris disks), southern hemispheredisks), southern hemisphere• EVLA advantages EVLA advantages : finer spectral : finer spectral resolution (correlator), longer baselines, resolution (correlator), longer baselines, already in VLBA, northern hemispherealready in VLBA, northern hemisphere• A careful comparison between EVLA and ALMA A careful comparison between EVLA and ALMA is needed to determine how often Band 1/Q-is needed to determine how often Band 1/Q-band can be observed!band can be observed!

Summary and Final Summary and Final PointsPoints

Summary and Final Summary and Final PointsPoints



• Band 1 would add 31-45 GHz capability to Band 1 would add 31-45 GHz capability to ALMA, perhaps extend to 50 GHz?ALMA, perhaps extend to 50 GHz?• Strong science cases exist for Band 1, Strong science cases exist for Band 1, that enhance or extend ALMA capabilitiesthat enhance or extend ALMA capabilities• Band 1 is relatively inexpensive, $10-20M, Band 1 is relatively inexpensive, $10-20M, depending on designdepending on design• relationship with EVLA needs to be relationship with EVLA needs to be carefully addressedcarefully addressed• input from community needed, please input from community needed, please contact me if you wish to contribute!contact me if you wish to contribute!



[email protected]@nrc-cnrc.gc.cacnrc.gc.ca

The Science Case for Band 1 James Di Francesco Herzberg Institute of Astrophysics Victoria, BC,...

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