LINE DERIVED INFRARED EXTINCTION TOWARD THE GALACTIC CENTER

We derive the extinction curve toward the Galactic center (GC) from 1 to 19 μm. We use hydrogen emission lines of the minispiral observed by ISO-SWS and SINFONI. The extinction-free flux reference is the 2 cm continuum emission observed by the Very Large Array. Toward the inner 14″ × 20″, we find an extinction of A2.166 μm = 2.62 ± 0.11, with a power-law slope of α = −2.11 ± 0.06 shortward of 2.8 μm, consistent with the average near-infrared slope from the recent literature. At longer wavelengths, however, we find that the extinction is grayer than shortward of 2.8 μm. We find that it is not possible to fit the observed extinction curve with a dust model consisting of pure carbonaceous and silicate grains only, and the addition of composite particles, including ices, is needed to explain the observations. Combining a distance-dependent extinction with our distance-independent extinction, we derive the distance to the GC to be R0 = 7.94 ± 0.65 kpc. Toward Sgr A* (r < 0.″5), we obtain AH = 4.21 ± 0.10, AKs = 2.42 ± 0.10, and AL′ = 1.09 ± 0.13.

[1]  J. L. Bourlot,et al.  The global dust SED: tracing the nature and evolution of dust with DustEM , 2010, 1010.2769.

[2]  A. Tielens,et al.  The 9.7 and 18 μm silicate absorption profiles towards diffuse and molecular cloud lines-of-sight , 2010, 1012.1698.

[3]  Ž. Ivezić,et al.  THE BLUE TIP OF THE STELLAR LOCUS: MEASURING REDDENING WITH THE SLOAN DIGITAL SKY SURVEY , 2010, 1009.4933.

[4]  R. Genzel,et al.  The galactic center massive black hole and nuclear star cluster , 2010, 1006.0064.

[5]  Cfa,et al.  Interstellar extinction and the distribution of stellar populations in the direction of the ultra-deep Chandra Galactic field , 2010, 1003.2965.

[6]  D. Gratadour,et al.  GC-IRS13E—A PUZZLING ASSOCIATION OF THREE EARLY-TYPE STARS , 2010, 1003.1717.

[7]  Aigen Li,et al.  Toward understanding the 3.4 μm and 9.7 μm extinction feature variations from the local diffuse interstellar medium to the Galactic center , 2008, 0812.2016.

[8]  K. Mužić,et al.  Peering through the veil: near-infrared photometry and extinction for the Galactic nuclear star cluster , 2009, 0912.1273.

[9]  S. Majewski,et al.  LIFTING THE DUSTY VEIL WITH NEAR- AND MID-INFRARED PHOTOMETRY. II. A LARGE-SCALE STUDY OF THE GALACTIC INFRARED EXTINCTION LAW , 2009 .

[10]  S. Majewski,et al.  Lifting the Dusty Veil II: A Large-Scale Study of the Galactic Infrared Extinction Law , 2009, 0910.4403.

[11]  B. Jiang,et al.  MID-INFRARED EXTINCTION AND ITS VARIATION WITH GALACTIC LONGITUDE , 2009, 0910.3037.

[12]  M. Asplund,et al.  The chemical composition of the Sun , 2009, 0909.0948.

[13]  T. Paumard,et al.  AN EXTREMELY TOP-HEAVY INITIAL MASS FUNCTION IN THE GALACTIC CENTER STELLAR DISKS , 2009, 0908.2177.

[14]  M. Hoare,et al.  The slope of the near-infrared extinction law , 2009, 0908.1601.

[15]  M. Tamura,et al.  A near-infrared survey of Miras and the distance to the Galactic Centre , 2009, 0907.2761.

[16]  B. Skiff,et al.  VizieR Online Data Catalog , 2009 .

[17]  A. Dambis.  The kinematics and zero‐point of the log P–〈MK〉 relation for Galactic RR Lyrae variables via statistical parallax , 2009 .

[18]  Edward L. Fitzpatrick,et al.  AN ANALYSIS OF THE SHAPES OF INTERSTELLAR EXTINCTION CURVES. VI. THE NEAR-IR EXTINCTION LAW , 2009, 0905.0133.

[19]  T. Paumard,et al.  EVIDENCE FOR X-RAY SYNCHROTRON EMISSION FROM SIMULTANEOUS MID-INFRARED TO X-RAY OBSERVATIONS OF A STRONG Sgr A* FLARE , 2009, 0903.3416.

[20]  J. Melnick,et al.  The massive star initial mass function of the Arches cluster , 2009, 0903.2222.

[21]  M. Tamura,et al.  INTERSTELLAR EXTINCTION LAW TOWARD THE GALACTIC CENTER III: J, H, KS BANDS IN THE 2MASS AND THE MKO SYSTEMS, AND 3.6, 4.5, 5.8, 8.0 μm IN THE SPITZER/IRAC SYSTEM , 2009, 0902.3095.

[22]  U. Florida,et al.  The complex, variable near-infrared extinction towards the Nuclear Bulge , 2009, 0901.1987.

[23]  R. Genzel,et al.  MONITORING STELLAR ORBITS AROUND THE MASSIVE BLACK HOLE IN THE GALACTIC CENTER , 2008, 0810.4674.

[24]  S. Trippe,et al.  EVIDENCE FOR WARPED DISKS OF YOUNG STARS IN THE GALACTIC CENTER , 2008, 0811.3903.

[25]  France,et al.  Kinematics of the old stellar population at the galactic centre , 2008, 0810.1040.

[26]  Jessica R. Lu,et al.  Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits , 2008, 0808.2870.

[27]  M. Groenewegen.  The red clump absolute magnitude based on revised Hipparcos parallaxes , 2008, 0807.2764.

[28]  Ryo Kandori,et al.  The Interstellar Extinction Law toward the Galactic Center. II. V, J, H, and Ks Bands , 2008, 0802.3559.

[29]  A. Udalski,et al.  The distance to the Galactic Centre based on Population-II Cepheids and RR Lyrae stars , 2008, 0801.2652.

[30]  Richard G. Arendt,et al.  Point Sources from a Spitzer IRAC Survey of the Galactic Center , 2007, 0709.3113.

[31]  K. Cunha,et al.  Chemical Abundances of Luminous Cool Stars in the Galactic Center from High-Resolution Infrared Spectroscopy , 2007, 0707.2610.

[32]  Jessica R. Lu,et al.  A Constant Spectral Index for Sagittarius A* during Infrared/X-Ray Intensity Variations , 2007, 0706.1782.

[33]  J. Alves,et al.  The Infrared Extinction Law at Extreme Depth in a Dark Cloud Core , 2007, 0704.3203.

[34]  菅沼 正洋,et al.  日本天文学会 早川幸男基金による渡航報告書 : The Central Engine of Active Galactic Nuclei , 2007 .

[35]  K. Flaherty,et al.  Infrared Extinction toward Nearby Star-forming Regions , 2007, astro-ph/0703777.

[36]  Near-infrared extinction in the coalsack globule 2 , 2006, astro-ph/0612620.

[37]  M. Tamura,et al.  The Distance to the Galactic Center Derived from Infrared Photometry of Bulge Red Clump Stars , 2006, astro-ph/0607408.

[38]  M. Lombardi,et al.  2MASS wide field extinction maps. I. The Pipe nebula , 2006, astro-ph/0606670.

[39]  Stefan Gillessen,et al.  SINFONI data reduction software , 2006 .

[40]  T. Paumard,et al.  Stellar and wind properties of massive stars in the central parsec of the Galaxy , 2006, Proceedings of the International Astronomical Union.

[41]  D. Froebrich,et al.  Extinction techniques and impact on dust property determination , 2006, astro-ph/0604240.

[42]  M. Tamura,et al.  Near-Infrared Extinction Law in the ρ Ophiuchi and Chamaeleon Dark Clouds , 2006 .

[43]  T. Paumard,et al.  The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics, and Formation , 2006, astro-ph/0601268.

[44]  M. Tamura,et al.  Interstellar Extinction Law in the J, H, and Ks Bands toward the Galactic Center , 2006, astro-ph/0601174.

[45]  T. Paumard,et al.  Variations in the Spectral Slope of Sagittarius A* during a Near-Infrared Flare , 2005, astro-ph/0511302.

[46]  A. Omont,et al.  Extinction at 7 ${\rm \mu}$m and 15 ${\rm \mu}$m from the ISOGAL survey , 2005, astro-ph/0509657.

[47]  T. Henning,et al.  Dust extinction and absorption: the challenge of porous grains , 2005, astro-ph/0509277.

[48]  A. Robin,et al.  Modelling the Galactic Interstellar Extinction Distribution in Three Dimensions , 2005, astro-ph/0604427.

[49]  Norbert Hubin,et al.  SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month , 2005 .

[50]  Can Fluffy Dust Alleviate the Subsolar Interstellar Abundance Problem , 2005, astro-ph/0503564.

[51]  The near-infrared extinction law in regions of high AV , 2005, astro-ph/0502407.

[52]  W. Vacca,et al.  “The Mauna Kea Observatories Near‐Infrared Filter Set. III. Isophotal Wavelengths and Absolute Calibration” (PASP, 117, 421 [2005]) , 2005, astro-ph/0502120.

[53]  L- and M-band imaging observations of the Galactic Center region , 2004, astro-ph/0411798.

[54]  The Wavelength Dependence of Interstellar Extinction from 1.25 to 8.0 μm Using GLIMPSE Data , 2004, astro-ph/0406403.

[55]  H. Shukla,et al.  Dense, Ionized, and Neutral Gas Surrounding Sagittarius A* , 2004, astro-ph/0408136.

[56]  E. Dwek.  Galactic Center Extinction: Evidence of Metallic Needles in the General Interstellar Medium , 2004, astro-ph/0407005.

[57]  B. Draine,et al.  Astrophysics of Dust , 2004 .

[58]  F. Rigaut,et al.  The nature of the Galactic Center source IRS 13 revealed by high spatial resolution in the infrared , 2004, astro-ph/0404450.

[59]  A. Tielens,et al.  The Absence of Crystalline Silicates in the Diffuse Interstellar Medium , 2004, astro-ph/0403609.

[60]  T. Sumi.  Extinction map of the Galactic centre: OGLE‐II Galactic bulge fields , 2003, astro-ph/0309206.

[61]  Richard G. Arendt,et al.  Interstellar Dust Models Consistent with Extinction, Emission, and Abundance Constraints , 2003, astro-ph/0312641.

[62]  D. Rouan,et al.  Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre , 2003, Nature.

[63]  Marcia J. Rieke,et al.  Hubble Space Telescope Paα and 1.9 Micron Imaging of Sagittarius A West , 2003 .

[64]  K. Sellgren,et al.  Really Cool Stars and the Star Formation History at the Galactic Center , 2003, astro-ph/0307291.

[65]  R. Abuter,et al.  A Geometric Determination of the Distance to the Galactic Center , 2003, astro-ph/0306220.

[66]  M. Rieke,et al.  HST Paschen alpha and 1.9 micron imaging of Sgr A West , 2003, astro-ph/0305350.

[67]  B. Draine.  INTERSTELLAR DUST GRAINS , 2003, astro-ph/0304489.

[68]  Norbert N. Hubin,et al.  SINFONI - Integral field spectroscopy at 50 milli-arcsecond resolution with the ESO VLT , 2003, SPIE Astronomical Telescopes + Instrumentation.

[69]  A. Omont,et al.  The ISOGAL field FC-01863+00035: Mid-IR interstellar extinction and stellar populations , 2003, astro-ph/0302411.

[70]  M. Rawlings,et al.  Infrared and visual interstellar absorption features towards heavily reddened field stars , 2003, astro-ph/0302060.

[71]  Norbert N. Hubin,et al.  Implementation of MACAO for SINFONI at the VLT, in NGS and LGS modes , 2003, SPIE Astronomical Telescopes + Instrumentation.

[72]  A. Udalski.  The Optical Gravitational Lensing Experiment: Is Interstellar Extinction toward the Galactic Center Anomalous? , 2002, astro-ph/0210367.

[73]  Martin F. Kessler,et al.  The calibration legacy of the ISO Mission , 2003 .

[74]  Liverpool John Moores University,et al.  Population effects on the red giant clump absolute magnitude: The K-band , 2002, astro-ph/0208057.

[75]  S. Kenyon,et al.  A Near-Infrared Imaging Survey of Coalsack Globule 2 , 2002, astro-ph/0207099.

[76]  E. Feigelson,et al.  A Chandra Study of Sagittarius A East: A Supernova Remnant Regulating the Activity of Our Galactic Center? , 2001, astro-ph/0102183.

[77]  Y. Pendleton,et al.  The Organic Refractory Material in the Diffuse Interstellar Medium: Mid-Infrared Spectroscopic Constraints , 2002 .

[78]  D. Calzetti.  The Dust Opacity of Star‐forming Galaxies , 2001, astro-ph/0109035.

[79]  J. Weingartner,et al.  Dust Grain-Size Distributions and Extinction in the Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud , 2001 .

[80]  M. Gerin,et al.  ISOCAM-CVF 5-12 Micron Spectroscopy of Ultraluminous Infrared Galaxies , 2001, astro-ph/0101187.

[81]  A. Sternberg,et al.  Near-Infrared Integral Field Spectroscopy and Mid-Infrared Spectroscopy of the Starburst Galaxy M82 , 2001, astro-ph/0101153.

[82]  A. Marconi,et al.  Dust in active nuclei. I. evidence for anomalous properties , 2000, astro-ph/0010009.

[83]  B. Draine,et al.  Infrared Emission from Interstellar Dust Ii. the Diffuse Interstellar Medium , 2000 .

[84]  J. Weingartner,et al.  Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC , 2000, astro-ph/0008146.

[85]  D. Lutz,et al.  The Composition and Distribution of Dust along the Line of Sight toward the Galactic Center , 2000, astro-ph/0002421.

[86]  C. Pichon,et al.  Stellar dynamics in the Galactic centre: Proper motions and anisotropy , 2000, astro-ph/0001428.

[87]  A. Kinney,et al.  The Dust Content and Opacity of Actively Star-forming Galaxies , 1999, astro-ph/9911459.

[88]  T. Prusti,et al.  Observations of Solid Carbon Dioxide in Molecular Clouds with the Infrared Space Observatory , 1999 .

[89]  M. Sauvage,et al.  Dust in an Extremely Metal-Poor Galaxy: Mid-infrared Observations ofSBS 0335–052 , 1998, astro-ph/9811126.

[90]  F. Yusef-Zadeh,et al.  Proper Motions of Ionized Gas at the Galactic Center: Evidence for Unbound Orbiting Gas , 1998, astro-ph/9803231.

[91]  E. Lada,et al.  The Near-Infrared Extinction Law and Limits on the Pre-Main-Sequence Population of the ρ Ophiuchi Dark Cloud , 1998 .

[92]  Howard A. Bushouse,et al.  Astronomical Data Analysis Software and Systems VII , 1998 .

[93]  T. Prusti,et al.  Infrared Spectroscopy of Dust in the Diffuse Interstellar Medium toward Cygnus OB2 No. 12 , 1997 .

[94]  J. Mathis.  Dust Models with Tight Abundance Constraints , 1996 .

[95]  K. Sellgren,et al.  JHKL Photometry and the K-Band Luminosity Function at the Galactic Center , 1996, astro-ph/9604109.

[96]  W. Goss,et al.  Kinematics of the Ionized Gas in Sagittarius A West: Mass Estimates of the Inner 0.13 Parsecs of the Galaxy , 1996 .

[97]  Laird M. Close,et al.  The peculiar population of hot stars at the galactic center , 1996 .

[98]  J. S. Jones,et al.  Interstellar Extinction from 0.35 to 2.2 Microns: A Study Based on Luminous Southern Stars , 1995 .

[99]  E. Becklin,et al.  Hubble Space Telescope observations of the galactic center region at 1.02 micron , 1993 .

[100]  W. Goss,et al.  Multiconfiguration VLA H92-alpha observations of Sagittarius A West at 1 arcsecond resolution , 1993 .

[101]  M. Wardle,et al.  Evidence for the Interaction of the IRS 16 Wind with the Ionized and Molecular Gas at the Galactic Center , 1993 .

[102]  W. Goss,et al.  Anomalously high apparent abundances of singly ionized helium in the Galactic H II region W3A , 1992 .

[103]  Alfred Krabbe,et al.  A cluster of He I emission-line stars in the Galactic center , 1991 .

[104]  W. Goss,et al.  VLA Radio Recombination Line Observations of Sagittarius A West , 1991 .

[105]  C. Masson,et al.  CO J = 3--2 Observations of the Neutral Disk in Sagittarius A West , 1990 .

[106]  J. Mathis,et al.  The relationship between infrared, optical, and ultraviolet extinction , 1989 .

[107]  Marcia J. Rieke,et al.  Origin of the excitation of the Galactic center , 1989 .

[108]  P. Roche,et al.  Infrared spectroscopy of dust in the Taurus dark clouds: ice and silicates , 1988 .

[109]  D. Whittet.  On the nature and environment of Omicron Scorpii , 1988 .

[110]  M. Wright,et al.  Aperture synthesis observations of the circumnuclear ring in the Galactic center , 1987 .

[111]  M. Reid,et al.  The distance to the center of the Galaxy , 1987 .

[112]  D. G. Hummer,et al.  Recombination-line intensities for hydrogenic ions. I - Case B calculations for H I and He II. [in astronomical objects , 1987 .

[113]  J. Mathis.  Interstellar dust and extinction , 1987 .

[114]  P. Roche,et al.  An investigation of the interstellar extinction – II. Towards the mid-infrared sources in the Galactic centre , 1985 .

[115]  G. Rieke,et al.  The interstellar extinction law from 1 to 13 microns. , 1985 .

[116]  D. Depoy,et al.  The location of infrared sources in the galactic center from a deep 1 micron CCD image , 1984 .

[117]  P. Roche,et al.  An investigation of the interstellar extinction. I: Towards dusty WC Wolf-Rayet stars , 1984 .

[118]  H. Liszt,et al.  Sagittarius A and its environment , 1984 .

[119]  M. Claussen,et al.  High-resolution observations of ionized gas in central 3 parsecs of the Galaxy: possible evidence for infall , 1983, Nature.

[120]  Dan McCammon,et al.  Interstellar photoelectric absorption cross-sections, 0.03-10 keV , 1983 .

[121]  I. Gatley,et al.  Far-infrared observations of Sagittarius A - The luminosity and dust density in the central parsec of the Galaxy , 1982 .

[122]  R. Puetter,et al.  The 4 to 8 micron spectrum of the galactic center , 1979 .

[123]  Blair D. Savage,et al.  Observed Properties of Interstellar Dust , 1979 .

[124]  B. Savage,et al.  A survey of interstellar H I from L-alpha absorption measurements. II , 1978 .

[125]  D. York,et al.  Infrared colors and the diffuse interstellar bands , 1978 .

[126]  K. Nordsieck,et al.  The Size distribution of interstellar grains , 1977 .

[127]  E. Becklin,et al.  Infrared observations of the galactic center. , 1967 .

[128]  D. Menzel,et al.  Physical Processes in Gaseous Nebulae. III. The Balmer Decrement. , 1938 .