We review the results from our studies, and previous published work, on the spatially resolved physical properties of a sample of H II/BCD galaxies, as obtained mainly from integral-field unit spectroscopy with Gemini/GMOS and VLT/VIMOS. We confirm that, within observational uncertainties, our sample galaxies show nearly spatially constant chemical abundances similar to other low-mass starburst galaxies. They also show He II？？ 4686 emission with the properties being suggestive of a mix of excitation sources and with Wolf-Rayet stars being excluded as the primary ones. Finally, in this contribution, we include a list of all H II/BCD galaxies studied thus far with integral-field unit spectroscopy. 1. Introduction The concept of compact galaxies was introduced by Zwicky [1], who has described them as “galaxies barely distinguishable from stars” on the Palomar Sky Survey plates. The term blue compact dwarf (BCD) galaxies [2] identify those objects that show low luminosity, small linear dimensions, strong emission lines superposed on a blue continuum, and spectral properties that indicate low chemical abundances. BCDs form a subset of H II galaxies, a large number of which have been identified on objective prism surveys by [3–6] by the presence of strong emission lines, similar to Giant H II regions (GH IIRs) in our galaxy. Here, we will refer to H II/BCD galaxies as objects with a metallicity (e.g., [7]), low luminosity ( ), and gas-rich objects (e.g., [8]) undergoing vigorous starburst activity in a relatively small physical size (？1？Kpc). The star forming component, in these objects, typically contains multiple knots of star-formation with unresolved ensembles of young star clusters (e.g., [9, 10]). The hypothesis of these systems being young, forming their first generation of stars, has been discarded by the detection of an evolved underlying stellar host with an age 1？Gyr, in the majority of the nearby H II/BCD population (e.g., [11, 12]). Figure 1 shows the optical spectrum of the galaxy Tol 2146-391 obtained using integral field unit (IFU) observations with Gemini/GMOS. In this figure, we label the most important emission lines used in our studies, in particular, the strong Balmer hydrogen recombination lines and collisionally excited emission lines, such as [O？II] 3726,3729, [O？III] 4363, [O？III] 5007, [S？II] 6717,6731, and [N？II] 6584, which have been used for the determination of physical conditions (e.g., electron temperature and density) and chemical abundances (e.g., oxygen, nitrogen, etc.). We also detect in some of our galaxies the
References
[1]
I. F. Zwicky, “Compact galaxies and compact parts of galaxies. I,” The Astrophysical Journal, vol. 140, p. 1467, 1964.
[2]
T. X. Thuan and G. E. Martin, “Blue compact dwarf galaxies. I. Neutral hydrogen observations of 115 galaxies,” The Astrophysical Journal, vol. 247, pp. 823–848, 1981.
[3]
G. Haro, “Preliminary note on blue emission-line galaxies,” BOTT, vol. 2, no. 14, pp. 8–18, 1956.
[4]
I. F. Zwicky, “Compact galaxies and compact parts of galaxies. II,” The Astrophysical Journal, vol. 143, p. 192, 1966.
[5]
B. E. Markarian, “Galaxies with an ultraviolet continuum,” Astrofizika, vol. 3, pp. 24–38, 1967.
[6]
W. L. W. Sargent and L. Searle, “Isolated extragalactic H ？？ regions,” The Astrophysical Journal, vol. 162, pp. L155–L160, 1970.
[7]
D. Kunth and W. L. W. Sargent, “Spectrophotometry of 12 metal-poor galaxies—implications for the primordial helium abundance,” The Astrophysical Journal, vol. 273, pp. 81–98, 1983.
[8]
M. E. Filho, B. Winkel, J. S. Almeida, et al., “Extremely metalpoor galaxies: the HI content,” Astronomy & Astrophysics, vol. 558, article A18, 30 pages, 2013.
[9]
P. Lagos, E. Telles, and J. Melnick, “Narrow-band Hβ images of star-formation regions in H ？？ galaxies,” Astronomy & Astrophysics, vol. 476, no. 1, pp. 89–96, 2007.
[10]
P. Lagos, E. Telles, A. Nigoche-Netro, and E. R. Carrasco, “Star cluster complexes and the host galaxy in three H ？？ galaxies: Mrk 36, UM 408, and UM 461,” Astronomical Journal, vol. 142, no. 5, article 162, 2011.
[11]
P. Papaderos, H.-H. Loose, T. X. Thuan, and K. J. Fricke, “Optical structure and star formation in blue compact dwarf galaxies I. Observations and profile decomposition,” Astronomy and Astrophysics Supplement Series, vol. 120, no. 2, pp. 207–228, 1996.
[12]
E. Telles and R. Terlevich, “The VRI colours of H ？？ galaxies,” Monthly Notices of the Royal Astronomical Society, vol. 286, no. 1, pp. 183–208, 1997.
[13]
P. Papaderos, Y. I. Izotov, K. J. Fricke, T. X. Thuan, and N. G. Guseva, “On the age of the nearby blue compact dwarf galaxy SBS 0335-052,” Astronomy & Astrophysics, vol. 338, no. 1, pp. 43–55, 1998.
[14]
P. Papaderos, N. G. Guseva, Y. I. Izotov, and K. J. Fricke, “Extremely metal-poor star-forming galaxies,” Astronomy & Astrophysics, vol. 491, no. 1, pp. 113–129, 2008.
[15]
G. Tenorio-Tagle, “Interstellar matter hydrodynamics and the dispersal and mixing of heavy elements,” Astronomical Journal, vol. 111, no. 4, pp. 1641–1650, 1996.
[16]
H. A. Kobulnicky and E. D. Skillman, “Elemental abundance variations and chemical enrichment from massive stars in starbursts. II. NGC 1569,” Astrophysical Journal Letters, vol. 489, no. 2, pp. 636–655, 1997.
[17]
H. A. Kobulnicky and E. D. Skillman, “Testing CNO enrichment scenarios in metal-poor galaxies with hubble space telescope spectroscopy,” Astrophysical Journal Letters, vol. 497, no. 2, pp. 601–617, 1998.
[18]
P. Lagos, E. Telles, C. Mu？oz-Tu？án, E. R. Carrasco, F. Cuisinier, and G. and Tenorio-Tagle, “On the compact H II galaxy UM 408 as seen by GMOS-IFU: physical conditions,” The Astronomical Journal, vol. 137, no. 6, pp. 5068–5079, 2009.
[19]
M. G. Edmunds and B. E. J. Pagel, “Nitrogen synthesis and the “age” of galaxies,” Monthly Notices of the Royal Astronomical Society, vol. 185, pp. 77–80, 1978.
[20]
D. Alloin, S. Collin-Souffrin, M. Joly, and L. Vigroux, “Nitrogen and oxygen abundances in galaxies,” Astronomy & Astrophysics, vol. 78, pp. 200–216, 1979.
[21]
Y. I. Izotov and T. X. Thuan, “Heavy-element abundances in blue compact galaxies,” Astrophysical Journal Letters, vol. 511, no. 2, pp. 639–659, 1999.
[22]
D. Kunth and G. ？stlin, “The most metal-poor galaxies,” The Astronomy and Astrophysics Review, vol. 10, no. 1-2, pp. 1–79, 2000.
[23]
P. Papaderos, Y. I. Izotov, T. X. Thuan et al., “The blue compact dwarf galaxy I Zw 18: a comparative study of its low-surface-brightness component,” Astronomy & Astrophysics, vol. 393, no. 2, pp. 461–483, 2002.
[24]
L. van Zee, J. J. Salzer, and M. P. Haynes, “Abundances in spiral galaxies: evidence for primary nitrogen production,” Astrophysical Journal Letters, vol. 497, no. 1, pp. L1–L4, 1998.
[25]
D. R. Garnett, “Nitrogen in irregular galaxies,” The Astrophysical Journal, vol. 363, pp. 142–153, 1990.
[26]
J. R. Walsh and J.-R. Roy, “Optical spectroscopic and abundance mapping of the amorphous galaxy NGC 5253,” Monthly Notices of the Royal Astronomical Society, vol. 239, pp. 297–324, 1989.
[27]
H. A. Kobulnicky, E. D. Skillman, J.-R. Roy, J. R. Walsh, and M. R. Rosa, “Hubble space telescope faint object spectrograph spectroscopy of localized chemical enrichment from massive stars in NGC 5253,” Astrophysical Journal Letters, vol. 477, no. 2, pp. 679–692, 1997.
[28]
A. R. López-Sánchez, C. Esteban, J. Garc？a-Rojas, M. Peimbert, and M. and Rodr？guez, “The localized chemical pollution in NGC 5253 revisited: results from deep Echelle spectrophotometry,” The Astrophysical Journal, vol. 656, no. 1, pp. 168–185, 2007.
[29]
M. S. Westmoquette, B. James, A. Monreal-Ibero, and J. R. Walsh, “Piecing together the puzzle of NGC 5253: abundances, kinematics and WR stars,” Astronomy & Astrophysics, vol. 550, article A88, 16 pages, 2013.
[30]
A. R. López-Sánchez, A. Mesa-Delgado, L. López-Martín, and C. Esteban, “The ionized gas at the centre of IC10: a possible localized chemical pollution by Wolf-Rayet stars,” Monthly Notices of the Royal Astronomical Society, vol. 411, no. 3, pp. 2076–2092, 2011.
[31]
B. L. James, Y. G. Tsamis, J. R. Walsh, M. J. Barlow, and M. S. Westmoquette, “The Lyman break analogue Haro 11: spatially resolved chemodynamics with VLT FLAMES,” Monthly Notices of the Royal Astronomical Society, vol. 430, pp. 2097–2112, 2013.
[32]
P. Lagos and C. Mu？oz-Tu？ón, “The spatial distribution of the He ？？λ4686 emission line in compact H ？？ galaxies,” European Astronomical Society, vol. 48, pp. 165–166, 2011.
[33]
P. Lagos, E. Telles, A. Nigoche-Netro, and E. R. Carrasco, “GMOS-IFU spectroscopy of the compact H ？？ galaxies Tol 0104？388 and Tol 2146？391: the dependence on the properties of the interstellar medium,” Monthly Notices of the Royal Astronomical Society, vol. 427, pp. 740–754, 2012.
[34]
B. L. James, Y. G. Tsamis, M. J. Barlow et al., “A VLT VIMOS study of the anomalous BCD Mrk 996: mapping the ionized gas kinematics and abundances,” Monthly Notices of the Royal Astronomical Society, vol. 398, no. 1, pp. 2–22, 2009.
[35]
E. Pérez-Montero, J. M. Vílchez, B. Cedrés et al., “Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies,” Astronomy & Astrophysics, vol. 532, article A141, 2011.
[36]
P. Lagos, E. Telles, and E. R. Carrasco, “Super star clusters in H ？？ galaxies,” in Proceedings of the International Astronomical Union (IAUS '10), vol. 5, symposium S266, pp. 447–450, 2010.
[37]
B. L. James, Y. G. Tsamis, and M. J. Barlow, “A VLT VIMOS integral-field spectroscopic study of perturbed blue compact galaxies: UM 420 and UM 462,” Monthly Notices of the Royal Astronomical Society, vol. 401, no. 2, pp. 759–774, 2010.
[38]
B. García-Lorenzo, L. M. Cairós, N. Caon, A. Monreal-Ibero, and C. Kehrig, “Integral field spectroscopy of blue compact dwarf galaxies,” Astrophysical Journal Letters, vol. 677, no. 1, pp. 201–218, 2008.
[39]
L. Vanzi, G. Cresci, M. Sauvage, and R. Thompson, “Integral field spectroscopy in the near infrared of NGC 3125-A and SBS 0335-052,” Astronomy & Astrophysics, vol. 534, article A70, 9 pages, 2011.
[40]
Y. I. Izotov, D. Schaerer, A. Blecha, F. Royer, N. G. Guseva, and P. North, “VLT/GIRAFFE spectroscopic observations of the metal-poor blue compact dwarf galaxy SBS 0335-052E,” Astronomy & Astrophysics, vol. 459, no. 1, pp. 71–84, 2006.
[41]
L. M. Cairós, N. Caon, B. García-Lorenzo, et al., “Mapping luminous blue compact galaxies with VIRUS-P: morphology, line ratios and kinematics,” Astronomy & Astrophysics, vol. 547, article A24, 15 pages, 2012.
[42]
L. Vanzi, G. Cresci, E. Telles, and J. Melnick, “Integral field near-infrared spectroscopy of ？？ Zw 40,” Astronomy & Astrophysics, vol. 486, no. 2, pp. 393–403, 2008.
[43]
V. Bordalo, H. Plana, and E. Telles, “The internal kinematics of the H ？？ galaxy ？？ Zw 40,” Astrophysical Journal, vol. 696, no. 2, pp. 1668–1682, 2009.
[44]
T. Marquart, K. Fathi, G. ？stlin, N. Bergvall, R. J. Cumming, and P. Amram, “Star-gas decoupling and a non-rotating stellar core in He 2-10 Integral field spectroscopy with FLAMES/ARGUS,” Astronomy & Astrophysics, vol. 474, no. 1, pp. L9–L12, 2007.
[45]
G. Cresci, L. Vanzi, M. Sauvage, G. Santangelo, and P. van Der Werf, “Integral-field near-infrared spectroscopy of two blue dwarf galaxies: NGC 5253 and He 2-10,” Astronomy & Astrophysics, vol. 520, no. 11, article A82, 10 pages, 2010.
[46]
L. M. Cairós, N. Caon, C. Zurita, C. Kehrig, P. Weilbacher, and M. Roth, “Mapping the starburst in blue compact dwarf galaxies. PMAS integral field spectroscopy of Mrk 1418,,” Astronomy & Astrophysics, vol. 507, no. 3, pp. 1291–1301, 2009.
[47]
L. M. Cairós, N. Caon, C. Zurita, C. Kehrig, M. Roth, and P. Weilbacher, “Mapping the properties of blue compact dwarf galaxies: integral field spectroscopy with PMAS,” Astronomy & Astrophysics, vol. 520, no. 14, article A90, 26 pages, 2010.
[48]
L. M. Cairós, N. Caon, P. Papaderos et al., “New light in star-forming dwarf galaxies: the PMAS integral field view of the blue compact dwarf galaxy mrk 409,” Astrophysical Journal Letters, vol. 707, no. 2, pp. 1676–1690, 2009.
[49]
C. Kehrig, E. Perez-Montero, J. M. Vichez, et al., “Uncovering multiple Wolf-Rayet star clusters and the ionized ISM in Mrk 178: the closest metal-poor Wolf-Rayet H 00 galaxy,” Monthly Notices of the Royal Astronomical Society, vol. 432, no. 4, pp. 2731–2745, 2013.
[50]
B. L. James, Y. G. Tsamis, M. J. Barlow, J. R. Walsh, and M. S. Westmoquette, “The merging dwarf galaxy UM 448: chemodynamics of the ionized gas from VLT integral field spectroscopy,” Monthly Notices of the Royal Astronomical Society, vol. 428, no. 1, pp. 86–102, 2013.
[51]
A. Monreal-Ibero, J. M. Vílchez, J. R. Walsh, and C. MunozTunon, “A study of the interplay between ionized gas and star clusters in the central region of NGC 5253 with 2D spectroscopy,” Astronomy & Astrophysics, vol. 517, article A27, 19 pages, 2010.
[52]
A. Monreal-Ibero, J. R. Walsh, and J. M. Vílchez, “The ionized gas in the central region of NGC 5253. 2D mapping of the physical and chemical properties,” Astronomy & Astrophysics, vol. 544, article A60, 2012.
[53]
C. Kehrig, J. M. Vílchez, S. F. Sánchez, E. Telles, E. Pérez-Montero, and D. Martín-Gordón, “The interplay between ionized gas and massive stars in the H ？？ galaxy IIZw70: integral field spectroscopy with PMAS,” Astronomy & Astrophysics, vol. 477, no. 3, pp. 813–822, 2008.
[54]
P. Lagos, P. Papaderos, J. M. Gomes, L. R. Vega, and A. V. Smith, “On the properties of the interstellar medium in extremely metal-poor blue compact dwarf galaxies: GMOS-IFU spectroscopy of the double-knot galaxy HS2236+1344,” Astronomy & Astrophysics. In preparation.
[55]
N. G. Guseva, Y. I. Izotov, G. Stasinska, K. J. Fricke, C. Henkel, and P. Papaderos, “VLT spectroscopy of low-metallicity emission-line galaxies: abundance patterns and abundance discrepancies,” Astronomy & Astrophysics, vol. 529, article A149, 62 pages, 2011.
[56]
A. Nava, D. Casebeer, R. B. C. Henry, and D. Jevremovic, “On the determination of N and O abundances in low-metallicity systems,” Astrophysical Journal Letters, vol. 645, no. 2, pp. 1076–1091, 2006.
[57]
E. D. Skillman, R. C. Kennicutt, and P. W. Hodge, “Oxygen abundances in nearby dwarf irregular galaxies,” The Astrophysical Journal, vol. 347, pp. 875–882, 1989.
[58]
H. Lee, E. D. Skillman, and K. A. Venn, “The spatial homogeneity of nebular and stellar oxygen abundances in the Local Group dwarf irregular galaxy NGC 6822,” Astrophysical Journal Letters, vol. 642, no. 2, pp. 813–833, 2006.
[59]
K. V. Croxall, L. van Zee, H. Lee, et al., “Chemical abundances of seven irregular and three tidal dwarf galaxies in the M81 group,” The Astrophysical Journal, vol. 705, no. 1, pp. 723–738, 2009.
[60]
D. A. Berg, E. D. Skillman, A. R. Marble, et al., “Direct oxygen abundances for low-luminosity LVL galaxies,” The Astrophysical Journal, vol. 754, no. 2, article 98, 33 pages, 2012.
[61]
Y. I. Izotov, G. Stasińska, G. Meynet, N. G. Guseva, and T. X. Thuan, “The chemical composition of metal-poor emission-line galaxies in the data release 3 of the sloan digital sky survey,” Astronomy & Astrophysics, vol. 448, no. 3, pp. 955–970, 2006.
[62]
J. Brinchmann, D. Kunth, and F. Durret, “Galaxies with Wolf-Rayet signatures in the low-redshift Universe. A survey using the Sloan Digital Sky Survey,” Astronomy & Astrophysics, vol. 485, pp. 657–677, 2008.
[63]
A. R. López-Sánchez and C. Esteban, “Massive star formation in Wolf-Rayet galaxies, IV. Colours, chemical-composition analysis and metallicity-luminosity relations,” Astronomy & Astrophysics, vol. 517, article A85, 28 pages, 2010.
[64]
Y. I. Izotov, K. G. Noeske, N. G. Guseva, P. Papaderos, T. X. Thuan, and K. J. Fricke, “Discovery of the high-ionization emission line [Ne V] λ3426 in the blue compact dwarf galaxy Tol 1214-277,” Astronomy & Astrophysics, vol. 415, no. 2, pp. L27–L30, 2004.
[65]
D. Schaerer, “About the initial mass function and He ？？ emission in young starbursts,” The Astrophysical Journal, vol. 467, pp. L17–L20, 1996.
[66]
D. R. Garnett, R. C. Kennicutt Jr., Y.-H. Chu, and E. D. Skillman, “He？？ emission in extragalactic H ？？ regions,” Astrophysical Journal Letters, vol. 373, no. 2, pp. 458–464, 1991.
[67]
M. A. Dopita and R. S. Sutherland, “Spectral signatures of fast shocks. I. Low-density model grid,” Astrophysical Journal Supplement, vol. 102, pp. 161–188, 1996.
[68]
T. X. Thuan and Y. I. Izotov, “High-ionization emission in metal-deficient blue compact dwarf galaxies,” The Astrophysical Journal Supplement Series, vol. 161, no. 2, pp. 240–270, 2005.
[69]
N. G. Guseva, Y. I. Izotov, and T. X. Thuan, “A spectroscopic study of a large sample of Wolf-Rayet galaxies,” Astrophysical Journal Letters, vol. 531, no. 2, pp. 776–803, 2000.
[70]
M. Shirazi and J. Brinchmann, “Strongly star forming galaxies in the local Universe with nebular He II λ4686 emission,” Montly Notices of the Royal Astronomical Society, vol. 421, pp. 1043–1063, 2012.
