TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

More documents

Recommendations

Info

ogue and flagged pixels, using a mask of rogue pixels from the same campaign as the data. Next we remove the background. To do this we use the off positions for SL, SH, and LH; for LL we use the off order (for example, LL1 nod1 - LL2 nod1). The high resolution spectra (SH and LH) are extracted from the images using a scripted version of the SMART program (Higdon et al., 2004), using full-slit extraction. Due to the extended nature of IC 2448, the low resolution spectra (SL and LL) are extracted from the images manually in SMART using a fixed column extraction window of width 14.0 pixels (25. ′′ 2) for SL and 8.0 pixels (40. ′′ 8) for LL. The spectra are calibrated by multiplying by the relative spectral response function which is created by dividing the template of a standard star (HR 6348 for SL and LL, and ξ Dra for SH and LH) by the spectrum of the standard star extracted in the same way as the source (Cohen et al. (2003); G. C. Sloan, private communication). Spikes due to deviant pixels missed by the irsclean program are removed manually. The large aperture LH (11 ′′ .1 x 22 ′′ .3) and LL (10 ′′ .5 x 168 ′′ ) slits are big enough to contain all of the flux from IC 2448. This is supported by the fact that the continuum flux from IC 2448 in LH matches that from LL with no scaling between them. However, the smaller aperture SH (4 ′′ .7 x 11 ′′ .3) and SL (3 ′′ .6 x 57 ′′ ) slits are too small to contain the entire object. Thus we scale SL up to LL and SH up to LH. SL has a scaling factor of 2.30 and SH has a scaling factor of 3.00. No scaling factor is needed for orders within a module (for example, SL1, SL2, and SL3 all have the same scaling factor of 2.30). Additionally, there is no need of a scaling factor between the two nod positions. Figure 2.1 shows the average of the two nods of the Spitzer IRS spectrum of IC 2448. The peak of the continuum at ∼30 µm in Fλ units implies that the dust is cool, ∼100 K. No evidence of polycyclic aromatic hydrocarbons (PAHs) or silicate 33
dust is seen in the spectrum. We see lines from ions of H, Ar, Ne, S and O in the IR spectrum of IC 2448. Close-ups of the lines in the high resolution Spitzer IRS spectrum of IC 2448 are shown in Figure 2.2. High ionization lines of [O IV] (ionization potential IP = 55 eV) and [Ar V] (IP = 60 eV) are observed, but even higher ionization lines such as [Ne V] (IP = 97 eV) and [Mg V] (IP = 109 eV) are not observed, indicating that there is only a moderately hard radiation field. Low ionization lines that would come from the photodissociation region (PDR) such as [Ar II] (IP = 16 eV) and [Si II] (IP = 8 eV) are not observed. A complete list of the observed lines and their fluxes is given in Table 2.1. The highest flux lines in the SH module (10.51 µm[S IV] and 15.55 µm[Ne III]) have bumps on each side of them that are instrumental artifacts, possibly resulting from internal reflection in the SH module or an effect of photon-responsivity. The bumps are just visible in Figure 2.2 for the [S IV] line. However, the bumps contain a negligible amount of flux – only ∼3% and ∼1% of the flux in the main [S IV] and [Ne III] lines respectively, and we did not include these small contributions in our line flux measurements. The line fluxes are measured interactively in SMART for each nod position by performing a linear fit to the continuum on both sides of the line and then fitting a gaussian to the line. The values of the average line fluxes from both nod positions are given in Table 2.1. We estimate uncertainties in the line fluxes in two ways. In the first method, we propagate the uncertainties in the gaussian fit to the line flux to determine the uncertainty on the average flux from both nod positions. In the second method, we use the standard deviation of the fluxes measured in the two nod positions to determine the uncertainty on the average flux from both nod positions. We then take the final uncertainty as the greater of these two uncertainties. Lines fluxes typically have uncertainties � 10%; lines with larger uncertainties (� 15% and � 30%) are marked in Table 2.1. We determine 3σ upper 34
Page 1 and 2: TRACING ABUNDANCES IN GALAXIES WITH
Page 3 and 4: TRACING ABUNDANCES IN GALAXIES WITH
Page 5 and 6: BIOGRAPHICAL SKETCH Shannon was bor
Page 7 and 8: ACKNOWLEDGEMENTS First and foremost
Page 9 and 10: thank my husband Ryan. The rest of
Page 11 and 12: 3 Chemical Abundances and Dust in P
Page 13 and 14: LIST OF FIGURES 1.1 Diagram of the
Page 15 and 16: ditionally we find that these nebul
Page 17 and 18: seed nuclei relative to the β deca
Page 19 and 20: shape (Carollo et al., 2007). These
Page 21 and 22: Boltzmann velocity distribution cha
Page 23 and 24: etween recapture and photoionizatio
Page 25 and 26: a whole. Additionally, abundances f
Page 27 and 28: at the appropriate temperature and
Page 29 and 30: (a) 3.37 eV 1.40 eV 0.10 eV 0.04 eV
Page 31 and 32: (Iion), the radiative transition ra
Page 33 and 34: lines. For example, changing the ad
Page 35 and 36: Figure 1.4 Starburst99 synthetic sp
Page 37 and 38: Figure 1.5 Example of crystalline s
Page 39 and 40: H H H H H H H H H Anthanthrene C H
Page 41 and 42: year lifetime. Spitzer is in an Ear
Page 43 and 44: CHAPTER 2 THE SPITZER IRS INFRARED
Page 45: these elements than previous studie
Page 49 and 50: Figure 2.2 Close-ups of emission li
Page 51 and 52: 2.4 Optical and UV Data We compleme
Page 53 and 54: 2.5 Data Analysis Our goal is to ca
Page 55 and 56: 2.5.2 Electron Density We assume an
Page 57 and 58: Table 2.6 Electron temperatures ass
Page 59 and 60: O, N, and C. The helium ionic abund
Page 61 and 62: Barlow (1994) use UV lines for impo
Page 63 and 64: is a spherical nebula with a low ma
Page 65 and 66: CHAPTER 3 CHEMICAL ABUNDANCES AND D
Page 67 and 68: essential data on important ionizat
Page 69 and 70: are members of the Bulge, (Acker et
Page 71 and 72: Table 3.2 Properties of observed GB
Page 73 and 74: nod-averaged line fluxes. Uncertain
Page 75 and 76: Table 3.3 Multiplicative scaling fa
Page 77 and 78: Table 3.4 Observed infrared line fl
Page 79 and 80: 3.5 Data Analysis 3.5.1 Abundances
Page 81 and 82: Table 3.6 Comparison of the derived
Page 83 and 84: from the most reliable line(s), and
Page 85 and 86: Table 3.7 Electron temperatures and
Page 87 and 88: Table 3.9 Ionic abundances Ion x a
Page 89 and 90: 3.5.2 Crystalline Silicates Crystal
Page 91 and 92: argon, neon, and sulfur tend to be
Page 93 and 94: Figure 3.2 Continuum subtracted spe
Page 95 and 96: Figure 3.3 Profiles of PAH features
Page 97 and 98:
mean argon and sulfur abundances ar
Page 99 and 100:
of two smaller than that of Simpson
Page 101 and 102:
towards the Galactic Center. On the
Page 103 and 104:
Table 3.14 Parameters of linear fit
Page 105 and 106:
models that show how a binary compa
Page 107 and 108:
y an outer dense O-rich torus, indi
Page 109 and 110:
CHAPTER 4 ABUNDANCES IN H II REGION
Page 111 and 112:
expect their abundance ratio to rem
Page 113 and 114:
We extract spectra processed throug
Page 115 and 116:
Figure 4.2 IRS spectra of H II regi
Page 117 and 118:
IRS slits from these WIRC observati
Page 119 and 120:
S IV) we employ is equal to Te(O +2
Page 121 and 122:
Figure 4.3 M51 H II region Ne III/N
Page 123 and 124:
Figure 4.4 shows a plot of the (Ne
Page 125 and 126:
James Webb Space Telescope (JWST);
Page 127 and 128:
Bernard-Salas, J. & Tielens, A. G.
Page 129 and 130:
Edgar, R. G., Nordhaus, J., Blackma
Page 131 and 132:
Hummer, D. G., Berrington, K. A., E
Page 133 and 134:
Matsuura, M., Zijlstra, A. A., Mols
Page 135 and 136:
Pradhan, A. K., Montenegro, M., Nah
Page 137:
Vassiliadis, E. & Wood, P. R. 1993,
show all

TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?